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FAQs

BMW Differential and Gearing Upgrades

Upgrading various parts of the differential can have tremendous benefits in your car's performance. It's easy to forget that the differential is a source for making your car faster and handle better so it's often overlooked. The engine is not the only place to make the car faster. Our differential options vary from gearing upgrades to limited slip conversions. You can purchase the ring & pinion gear sets on their own (professional installation required) or have us build a diff around your own specifcations. The options are almost endless! Every custom-built diff is fully rebuilt with seals and bearings. We also design and supply bushing options to reduce driveline wind-up, finned differential covers for better cooling, and more!

Ratio Changes - Changing the differential gearing is one of the best and most-effective upgrades you can make on any BMW (old or new). By using a shorter (numerically higher) final drive ratio you are increasing your RPM relative to road speed - this puts you in a more powerful RPM range than before! Since you're in a 'meatier' part of the power band you're now putting down more power/torque to the ground. If you can trade outright top speed for faster acceleration at daily speeds then this is the perfect upgrade for you.

Limited Slip Upgrades - Sadly, many BMWs today are not equipped with a limited slip (posi-traction) differential. BMW has tried to compensate by using traction control that cuts power at the engine or applies the brakes to retard wheel spin (or a combination of both). But nothing beats the function and feel of a a true LSD which may be why BMW continues to use them in M cars. Our LSD upgrades can be done a number of different ways - a factory-type limited slip unit with either 2 or 3 clutch packs, helical type, OS Giken unit, or something truly custom. We can also vary ramp angles and setup to change the limited-slip behavior under acceleration, deceleration, and cornering. Need a custom diff? Call or e-mail to have a quote.
For accurate results, specify your model below.
This aluminum diff cover is off the Z4 Roadster and features fins on the underside for improved cooling. This is an absolute must for any E46 that sees track time, especially with an LSD installed. This is a direct bolt-on with the existing bolts and all drain and fill plugs transfer over as well. BMW recommends sealing the cover to the diff with black RTV silicone (no gasket).

This item fits the following BMWs:
1999-2006 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi (upgrade!)
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si (replacement)
Part #: 33117512980
Price: $159.95 (USD) 
Quantity:   

This seal is found where the driveshaft connects to the differential.

Genuine BMW Shaft Seal - 50X78X10/15
 

This item fits the following BMW Chassis:
E70 X5M,E71 X6M,E53 48IS,E38,E39,E53 X5,E63,E65,E70 X5,E71 X6,E82,E89 Z4,E90,E92,E93,F01,F02,F06,F10,F12,F13,F15,F16,F22,F30,F32,F33,F36
 

 

Part #: 33107609536
Price: $33.95 (USD) 
Quantity:   

If there was a Top 5 list of things to do on the E46 M3, a shorter gears would be in the top two... The gearing used to be overlooked when planning modifications but the 3.91 and 4.10 gears are now one of our biggest selling upgrades for the E46 M3! With a rear end gear upgrade you get the effects of adding horsepower but without adding any more stress to the engine or drivetrain. The R&P acts as a torque multiplier, getting you into the power band sooner in each gear. It's one of the best areas to get return from your modification spending. The shorter (numerically higher) rear end gears will give you better acceleration in all gears at any speed with few downsides. Want to make your car faster off the line or out of corners? Or avoid a downshift to pass on the highway? This is what you need. This 4.10 is the latest version from BMW Motorsport - shot peened and hardend for increased strength. The R&P can be installed on its own but for cars that have more than 60,000 miles it would be a better idea to rebuild the whole diff. The factory viscous limited slip units have a typical lifespan of 50-70,000 miles. We offer diff rebuilding with 4.10 or other gear options and you get a fully-rebuilt and serviced limited slip unit at the same time. Click here for our diff rebuild options.

4.10 Gearing Example: 2004 M3, 6-speed manual, 275/35-19" rear tires

Gear RatioGearSpeedRPM

40 MPH in 4th

3.624th40 MPH2,250 RPM

4.104th40 MPH2,550 RPM

70 MPH Cruise

3.626th70 MPH2,650 RPM

4.106th70 MPH3,000 RPM

5th Gear Speed at Redline

3.625th175 MPH8,000 RPM

4.105th154 MPH8,000 RPM

Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.


This item is the genuine BMW part and the ring & pinion set only. You will need to have this professionally installed into your existing differential. BMW does not supply differential rebuild parts (bearings, shims, plates, etc.) so only a qualified shop that is experienced in BMW diff rebuilding should perform this installation. We also offer built differentials and exchanges, click here.

This item fits the following BMWs:
2001-2006 E46 BMW M3
2004-2010 E60 BMW M5 (manual transmission only)

Part #: TMS21503
Price: $999.95 (USD) 
Quantity:   
The limited slip unit on the E46 M3 is designed to be a pure street car differential. It's simply not up to the rigors of professional or amateur racing. The OS Giken Super Lock LSD is giant step up in from a stock E46 M3 lsd unit. It's ready for the extreme conditions of racing, offers 100% progressive locking capability, and is able to do this while operating smoothly and quietly. It's use of advanced technologies that make it perfect for both street cars AND pro race cars... and everything in between. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've been using them in our own Championship winning E46 M3 race cars.

OS Giken incorporated revolutionary new ideas when developing the their own limited slip diff, utilizing their accumulated racing knowledge and experience and over 4 years of development. Their design uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The end result of their efforts is the OS Giken's OS Super Lock LSD which offers incredible durability and reliability on street and track driven BMWs. The use of highest quality materials, precise machining, forged gears and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). This is such a great design, in that it can be used in any situation -- whether it's for a street car, or a 100% Professional race car. Zero break-in required. Super smooth and quiet engagement, and 100% progressive locking capability. Professional installation is recommended.

This Limited Slip Differential Unit fits the following BMWs:
2001-2006 E46 M3 coupe & convertible
1991-1995 E34 M5 sedan
1999-2003 E39 M5 sedan
2006-2008 E85 Z4M Z4 M Coupe, Z4 M Roadster
Part #: BM237-HA
Price: $2079.95 (USD) 
Quantity:   
The 3.07 differential is an Original BMW part and used on the 330i ZHP Performance Package (manual transmission). This is a complete, fully-built differential that is a direct replacement swap for the stock 330i/ci 2.93 diff. On other models (323/325/328, Z4) you will need the 330's output shaft flanges (easy to install). You can find used output flanges online or we can sell you new flanges. The 3.07 gearing is 5% shorter than the stock 2.93 and will give a modest improvment in acceleration. Having the shorter ratio will put you in a better part of the RPM band for any given speed. This makes the car instantly quicker with more power and torque on tap. There's almost no downside aside from the higher revs will decrease fuel economy. Jumping from 2.93 to 3.07 is not a drastic change and was used by BMW to sell the ZHP package as a faster car than a standard 330i. For even better acceleration, try the 3.46 or 3.64 options in our custom differentials. The custom diffs will also give you a limited-slip option (this ZHP diff is still an open style).

This is an Original BMW part and carries the same BMW two year warranty as any other new BMW part. A core charge is required that can be refunded when your original diff is returned.

Example: 2002 330i, 5-speed manual, 245/40-17" rear tires
Gear RatioGearSpeedRPM
2.934th40 MPH2,000 RPM
3.074th40 MPH2,050 RPM
2.935th70 MPH2,800 RPM
3.075th70 MPH2,900 RPM
3.075th144 MPH*6,000 RPM
* - Theoretical speed for 3.07 gears at 6,000 RPM. It doesn't mean this speed is actually attainable. It's only offered for reference.

This item fits the following BMWs:
2001-2006 E46 BMW 330i 330ci 330xi, with manual transmission
1999-2006 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci (requires 330 output flanges)
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si (requires 330 output flanges)
Part #: 33107508099
Price: $1954.85 (USD) 
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

Gearing Changes Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Click the banner below for examples.

Example: 2006 330i, 6-speed manual, 255/35-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.154th40 MPH2,100 RPM
3.644th40 MPH2,400 RPM
3.914th40 MPH2,550 RPM
70 MPH Cruise
3.156th70 MPH2,500 RPM
3.646th70 MPH2,900 RPM
3.916th70 MPH3,100 RPM
5th Gear Speed @ 6,000 RPM
3.155th142 MPH6,000 RPM
3.645th123 MPH6,000 RPM
3.915th114 MPH6,000 RPM
Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your E90 will top out at.

Limited Slip Options. The non-M models of the E90 did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2006 E90 BMW 330i
Part #: TMS21525
Price: $1724.00 (USD) 
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

Gearing Changes The 325i and 328 come from the factory with a 3.23 ratio. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Click the banner below to see examples.

2006-2011 325i or 328i, 6-speed manual, 255/35-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.234th40 MPH2,150 RPM
3.644th40 MPH2,400 RPM
3.914th40 MPH2,550 RPM
70 MPH Cruise
3.236th70 MPH2,600 RPM
3.646th70 MPH2,900 RPM
3.916th70 MPH3,100 RPM
5th Gear Speed @ 6,000 RPM
3.235th138 MPH6,000 RPM
3.645th123 MPH6,000 RPM
3.915th114 MPH6,000 RPM
These are just a range using three gear ratios (stock, middle, extreme). Speeds and RPM will obviously change in between ratios.
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The non-M models of the E90 did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2006-2011 E90 E91 E92 E93 BMW 325i 328i
Part #: TMS21526
Price: $1724.00 (USD) 
As used on our Frozen Grey E92 M3
A custom differential is one of the best upgrades to have done to your E90 or E92 M3. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

Gearing The E9X M3 gearing depends on which transmission/clutch spec your car has - 6MT or the DCT. The DCT comes with a taller 3.15 gear set (taller than the 3.85 used in the manual transmission cars) to make up for the different transmission ratios and the additional 7th gear. But there's always more acceleration to be had with a shorter gear set and we have quite a few to choose from for either transmission. Your speed vs RPM obviously changes with a different gear set. Use the chart below for examples of the differences.

2009 M3, 7-speed DCT, 265/35-19" rear tires
(click to expand)
Gear RatioGearSpeedRPM
4th Gear @ 40 MPH
3.154th41 MPH2,750 RPM
3.624th39 MPH3,000 RPM
70 MPH Cruise
3.157th70 MPH2,800 RPM
3.627th70 MPH3,250 RPM
6th Gear Speed at Redline
3.156th171 MPH8,250 RPM
3.626th149 MPH8,250 RPM
Why 6th? Because 7th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 6th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.

Limited Slip Options The M3's M Variable locking differential is genius when it's working properly. Unfortunately, as many M3 owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2008-2011 E90 BMW M3 DCT - Sedan
2008-2013 E92 BMW M3 DCT - Coupe
2008-2013 E93 BMW M3 DCT - Convertible
Part #: TMS213596
Price: $3424.00 (USD) 
Changing the rear gearing on your 135i is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in the boost sooner for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels.

Gearing Changes All 135i differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 2.81 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the stock 2.56 or 2.81 is currently the only gear options offered at this time. The 2.81 is perfect for keeping the N55 engine on the boost. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. Refer to the chart below for examples on the difference.

2011 135i, 7-speed DCT, 245/35-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
2.564th40 MPH2,335 RPM
2.814th40 MPH2,564 RPM
70 MPH Cruise
2.566th70 MPH2,433 RPM
2.816th70 MPH2,670 RPM
6th Gear Speed @ 7,000 RPM
2.566th168 MPH7,000 RPM
2.816th153 MPH7,000 RPM
Speed in 6th gear at 7,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The 135i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2011-2012 E82 BMW 135i 7-speed DCT
Part #: TMS211251
Price: $2824.00 (USD) 
As used on the Lime Rock M3
A custom differential is one of the best upgrades to have done to your E90 or E92 M3. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

Gearing The E9X M3 gearing depends on which transmission/clutch spec your car has - 6MT or the DCT. The manual transmission cars have a relatively short 3.85 gear ratio on manual transmission cars. They could use a shorter gear because the engine redline is so high - the car has a long power band and the gear spacing allows you to stay well within that range. But there's always more acceleration to be had with a shorter gear set and we have quite a few to choose from for either transmission. Your speed vs RPM obviously changes with a different gear set. Use the chart below for examples of the differences.

2009 M3, 6-speed manual, 265/35-19" rear tires
(click to expand)
Gear RatioGearSpeedRPM
4th Gear @ 40 MPH
3.854th40 MPH2,350 RPM
4.104th40 MPH2,500 RPM
4.454th40 MPH2,700 RPM
70 MPH Cruise
3.856th70 MPH3,000 RPM
4.106th71 MPH3,250 RPM
4.456th71 MPH3,500 RPM
5th Gear Speed at Redline
3.855th168 MPH8,250 RPM
4.105th157 MPH8,250 RPM
4.455th145 MPH8,250 RPM
Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.

Limited Slip Options The M3's M Variable locking differential is genius when it's working properly. Unfortunately, as many M3 owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2008-2011 E90 BMW M3 6MT - Sedan
2008-2013 E92 BMW M3 6MT - Coupe
2008-2013 E93 BMW M3 6MT - Convertible
Part #: TMS20540
Price: $3924.00 (USD) 
This Genuine BMW speedometer / pulse generator is mounted in the back of the differential and provides wheel speed information to the instrument cluster speedometer.

This item fits the following BMWs:
1984-1987 E30 BMW 318i 325e 325es 325i 325ic 325is
1982-1988 E28 BMW 524td 528e 533i 535i 535is M5
1983-6/1987 E24 BMW 633csi 635csi M6
1981-1987 E23 BMW 733i 735i
Part #: 62161369906
Price: $108.95 (USD) 
Quantity:   
For the ultimate in track day performance, the M Performance Limited Slip Differential is here! The clutch-type mechanical differential features a 30% lockup on acceleration and 9% lockup on deceleration. The differential works with the existing DSC system to provide excellent traction wet or dry. It uses the stock 3.08 final drive ratio that the stock F30 335i / F32 435i uses, so fuel economy will not be affected. This item fits the following BMWs:
2012+ F30 BMW 335i - Sedan
2013+ F32 BMW 435i - Coupe
2013+ F33 BMW 435i Convertible - Convertible
Part #: 33107555607
Price: $2298.95 (USD) 
Quantity:   
If your MINI is only for competition use - autocross, time trial, or racing - this OS Giken LSD may be a better option than the standard 1.5-way unit. This race-spec LSD was developed over several seasons of competitive autocross. It uses a new high pressure ring for quicker response time and faster lockup. This makes it ideal for quick transitions and rapid on/off throttle motions typically encountered on the track. It's a one-way lockup so the car stays predictable under braking and gives the driver more feedback. For street use we prefer the normal 1.5-way setup because it's more progressive during lockup.

The biggest shortcoming of any MINI is not the lack of power - it's being able to put all of its useable power to the ground! The Cooper S is basically a one-wheel drive car and sending 200+ hp through that one tire does not live up to its full potential. A limited-slip differential is essential to any highly-tuned FWD car. The OS Giken Super-Lock is one of the most advanced clutch-type differentials on the market, and a favorite of autocrossers and road racers. The OS LSD for the MINI features ten clutch discs for a smooth and progressive lockup. By putting all of your available power to the ground you're at an instant advantage over the stock open-type differential. You'll be able to power through corners and on rough surfaces instead of uselessly spinning a wheel. Understeer is reduced by giving more bite to the tire that has the most traction. With an LSD in your MINI Cooper S you'll wonder why it wasn't first on your list to begin with (or why MINI/BMW left it out in the first place...).

The MNI OS Giken LSD uses a special 80W250 fluid that must be purchased separately.

This item fits the following BMWs:
2002-2006 R53 MINI MINI Cooper S (6MT manual transmission only)
2007-2013 R56 MINI MINI Cooper S (6MT manual transmission only)
Part #: MN024-HA
Price: $1789.00 (USD) 
Quantity:   
A custom differential is one of the best upgrades to have done to your E46 M3. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

Gearing The E46 M3 diff comes with a relatively short 3.62 gear ratio. They could use a shorter gear because the engine redline is so high - the car has a long power band and the gear spacing allows you to stay well within that range. There's always more acceleration to be had with a shorter gear set. BMW Motorsport supplies 3.91 or 4.10 options and there are other gear ratios to select in our custom builds. Your speed vs RPM obviously changes with a different gear set. Use the chart below for examples of the differences.

Gearing Charts:
2004 M3, 6-speed manual, 275/35-19" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.624th40 MPH2,250 RPM
3.914th40 MPH2,450 RPM
4.104th40 MPH2,550 RPM
70 MPH Cruise
3.626th70 MPH2,650 RPM
3.916th70 MPH2,900 RPM
4.106th70 MPH3,000 RPM
5th Gear Speed at Redline
3.625th175 MPH8,000 RPM
3.915th162 MPH8,000 RPM
4.105th154 MPH8,000 RPM
Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.

Limited Slip Options The M3's M Variable locking differential is genius when it's working properly. Unfortunately, as many M3 owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2001-2006 E46 BMW M3
Part #: TMS2052
Price: $2174.00 (USD) 
Changing the rear gearing on your Z4 35i is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in the boost sooner for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels.

Gearing Changes All Z4 differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 3.46 ring and pinion is now no more difficult than any other car. The stock 3.08 or extra tall 2.81 is offered for rebuilds as well. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. Refer to the chart below for examples on the difference.

2011 Z4 35i, 6-speed manual, 255/30-19" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.084th40 MPH1,973 RPM
3.464th40 MPH2,216 RPM
70 MPH Cruise
3.086th70 MPH2,525 RPM
3.466th70 MPH2,837 RPM
5th Gear Speed @ 6,000 RPM
3.085th145 MPH6,000 RPM
3.465th129 MPH6,000 RPM
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The Z4 35i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2009+ Z4 BMW Z4 sDrive35i
Part #: TMS217648
Price: $3299.00 (USD) 
A custom differential is one of the best upgrades to have done to your Z4 M. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

Gearing The MZ4 diff comes with a relatively short 3.62 gear ratio. They could use a shorter gear because the engine redline is so high - the car has a long power band and the gear spacing allows you to stay well within that range. But there's always more acceleration to be had with a shorter gear set. BMW Motorsport supplies 3.91 or 4.10 options and there are other gear ratios to select in our custom builds. Your speed vs RPM obviously changes with a different gear set. Use the chart below for examples of the differences.


Example: 2008 Z4 M, 6-speed manual, 255/40-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.624th39 MPH2,250 RPM
3.914th40 MPH2,500 RPM
4.104th40 MPH2,625 RPM
70 MPH Cruise
3.626th69 MPH2,750 RPM
3.916th70 MPH3,000 RPM
4.106th70 MPH3,150 RPM
5th Gear Speed at Redline
3.625th171 MPH8,000 RPM
3.915th158 MPH8,000 RPM
4.105th151 MPH8,000 RPM
Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M Coupe will top out at.

Limited Slip Options The M Variable locking differential is genius when it's working properly. Unfortunately, as many M3/M5/M6/Z4M owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2006-2008 E85 E86 BMW Z4 M Roadster M Coupe
Part #: TMS21531
Price: $2074.00 (USD) 
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

Gearing Changes Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Refer to the chart below for examples.

2002 330i, 5-speed manual, 245/40-17" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
2.934th40 MPH2,000 RPM
3.464th40 MPH2,300 RPM
3.914th40 MPH2,600 RPM
70 MPH Cruise
2.935th70 MPH2,800 RPM
3.465th70 MPH3,300 RPM
3.915th71 MPH3,750 RPM
5th Gear Speed @ 6,000 RPM
2.935th151 MPH6,000 RPM
3.465th128 MPH6,000 RPM
3.915th113 MPH6,000 RPM
These are just a range using three gear ratios (stock, middle, extreme). Speeds and RPM will obviously change in between ratios.
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.
2005 330i ZHP, 6-speed manual, 255/35-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.074th40 MPH2,050 RPM
3.464th40 MPH2,300 RPM
3.914th40 MPH2,550 RPM
70 MPH Cruise
3.076th70 MPH2,450 RPM
3.466th70 MPH2,750 RPM
3.916th70 MPH3,150 RPM
5th Gear Speed @ 6,000 RPM
3.075th146 MPH6,000 RPM
3.465th129 MPH6,000 RPM
3.915th114 MPH6,000 RPM
These are just a range using three gear ratios (stock, middle, extreme). Speeds and RPM will obviously change in between ratios.
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The non-M models of the E46, Z4, and E39 did not come with a limited slip unit. Instead, BMW used either the ASC (Accelerated Slip Control) or DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the ASC/DTC systems do not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut by ASC. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi
1997-2003 E39 BMW 525i 528i 530i
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si
Part #: TMS340178
Price: $1724.00 (USD) 
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

Gearing Changes All 335i/435i differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 3.46 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the 3.46 is currently the only gear option offered at this time but it's perfect for keeping the N55 engines on the boost. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Refer to the chart below for examples on the difference.

2014 335i, 6-speed manual, 255/30-19" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.234th40 MPH2,047 RPM
3.464th40 MPH2,192 RPM
70 MPH Cruise
3.236th70 MPH2,570 RPM
3.466th70 MPH2,752 RPM
5th Gear Speed @ 6,000 RPM
3.235th138 MPH6,000 RPM
3.465th129 MPH6,000 RPM
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The 335i/435i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. We offer several types of F30/F32 limited slip units:
  • traditional 2 or 3-disc LSD (40-60% fixed lock-up - more than the factory M Performance)
  • 3-disc LSD with variable ramp angles (user-variable lock-up)
  • Quaife helical (no clutch discs)
  • OS Giken Superlock multi-plate LSD (0-100% lock-up)
  • OS Giken TractionControlDiff multi-plate LSD (0-100% lock-up) (smoother and quieter version of Superlock)
    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2012+ F30 BMW 335i - Sedan
    2014+ F32 BMW 435i - Coupe
    2014+ F33 BMW 435i - Convertible
    2014+ F36 BMW 435i - Gran Coupe
  • Part #: TMS216177
    Price: $4148.00 (USD) 
    video: E92 335i with limited slip

    click for high quality
    A turbocharged BMW such as the 135i or 335i needs traction to put that power to the ground. The stock differential of both the 135i and 335i only put power to one wheel -- this just won't cut it! Upgrading to a limited slip differential means power to BOTH wheels, for better lauch, acceleration, and track handling. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've used their products on our own Championship winning E46 and E92 race cars.

    With the 135i/335i LSD unit, they have incorporated revolutionary new ideas into the design (4 years in the making!) which uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The end result of their efforts is the OS Giken's OS Super Lock LSD which offers incredible durability and reliability on street and track driven BMWs. The use of highest quality materials, precise machining, forged gears and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). Zero break-in required. Super smooth and quiet engagement, and 100% progressive locking capability.

    Installation note: BMW differentials use many unique and BMW-only parts and components. Only technicians who are experienced and familiar with BMW parts should perform the installation. The OS Giken LSD is the limited slip unit (or 'chunk') only. It replaces the stock non-LSD chunk but the original ring and pinion and other internals must be installed with the OS Giken unit. This unit will only work on 335i manual differentials with a bolt-in or modified ring gear. Proper setup and spacing is critical for long life operation. Incorrect installation will void the warranty. We also offer the TCD unit pre-installed - see our performance diff catalog for more info.

    The OS Giken Superlock Diff unit fits the following BMWs:
    2008-2012 E82 BMW 135i with manual transmission
    2007-2011 E90 BMW 335i - Sedan with manual transmission
    2007-2013 E92 BMW 335i 335is - Coupe with manual transmission
    2007-2013 E93 BMW 335i - Convertible with manual transmission
    Part #: BM531-HA
    Price: $4149.90 (USD) 
    This Genuine BMW speedometer / pulse generator is mounted in the back of the differential and provides wheel speed information to the instrument cluster speedometer. We also recommend getting the seal for the sensor #33111210739.

    This item fits the following BMWs:
    1988-1991 E30 BMW 318i 318is 318ic 325e 325es 325i 325ic 325is M3
    7/1987-1989 E24 BMW 635csi M6
    1997 Z3 BMW Z3 2.8
    1998-2002 Z3 BMW M Roadster M Coupe
    Part #: 62168355008
    Price: $49.95 (USD) 
    Quantity:   
    These 135 automatic limited slip upgrades will allow you to put the power down where/when you need it most. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

    The 135i deserved a limited slip but was not equipped with one from the factory. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

    There are no gearing options with the 135 auto diff. The standard 3.46 gear set is the only one available.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2008-2012 E82 BMW 135i with auto transmission (not DCT models)
    Part #: TMS21530
    Price: $3424.00 (USD) 
    One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

    Gearing Changes Most 335i differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 3.46 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the 3.46 is currently the only gear option offered at this time but it's perfect for keeping the N54 and N55 engines on the boost. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Refer to the chart below for examples on the difference.

    2009 335i, 6-speed manual, 255/30-19" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    3.084th41 MPH2,000 RPM
    3.464th40 MPH2,250 RPM
    70 MPH Cruise
    3.086th69 MPH2,500 RPM
    3.466th70 MPH2,800 RPM
    5th Gear Speed @ 6,000 RPM
    3.085th145 MPH6,000 RPM
    3.465th129 MPH6,000 RPM
    Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

    Limited Slip Options. The 335i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. We offer several types of limited slip units for the 335i:
  • traditional 2 or 3-disc LSD (40-60% fixed lock-up)
  • 3-disc LSD with variable ramp angles (user-variable lock-up)
  • Quaife helical (no clutch discs)
  • OS Giken Superlock multi-plate LSD (0-100% lock-up)
  • OS Giken TractionControlDiff multi-plate LSD (0-100% lock-up) (smoother and quieter version of Superlock)
    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    3/2007-2011 E90 BMW 335i with manual transmission
    3/2007-2012 E92 E93 BMW 335i with manual transmission
  • Part #: TMS21527
    Price: $2824.00 (USD) 
    Changing the rear gearing on your 135i is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in the boost sooner for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels.

    Gearing Changes All 135i differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 3.46 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the 3.46 upgrade is currently the only gear option offered at this time but it's perfect for keeping the N54 and N55 engines on the boost. The stock 3.08 is offered for rebuilds as well. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. Refer to the chart below for examples on the difference.

    2009 135i, 6-speed manual, 245/35-18" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    3.084th40 MPH2,000 RPM
    3.464th40 MPH2,250 RPM
    70 MPH Cruise
    3.086th69 MPH2,500 RPM
    3.466th70 MPH2,875 RPM
    5th Gear Speed @ 6,000 RPM
    3.085th143 MPH6,000 RPM
    3.465th128 MPH6,000 RPM
    Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

    Limited Slip Options. The 135i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2008-2012 E82 BMW 135i (not DCT models)
    Part #: TMS21529
    Price: $2824.00 (USD) 
    video: E92 335i with limited slip

    click for high quality
    A turbocharged BMW such as the 135i or 335i needs traction to put that power to the ground. The stock differential of both the 135i and 335i only put power to one wheel -- this just won't cut it! Upgrading to a limited slip differential means power to BOTH wheels, for better launch, acceleration, grip, and track handling. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've used their products on our own Championship winning E46 and E92 race cars.

    OS Giken's newest innovation is their quietest and smoothest limited slip unit yet - the Traction Control Differential (TCD). TCD is similar to their excellent Superlock differentials but with additional oil channels and pathways. The added lubrication makes diff operation smoother and quieter than before (not that there were many complaints to begin with). The locking engagement is more progressive than before which makes this diff more suitable for street driving. Track cars and drift cars should still use the Superlock LSD as it will transition to lock sooner. TCD is an evolution of a diff that was already extremely well-engineered for road and track use. Not willing to rest on their laurels, they took their superior engineering a step further.

    With the 135i/335i LSD unit, they have incorporated revolutionary ideas into the overall limited-slip design which uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The use of highest quality materials, precise machining, forged gears, and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). Zero break-in required. 100% progressive locking capability.

    As Used on Project E92 335i

    Installation note: BMW differentials use many unique and BMW-only parts and components. Only technicians who are experienced and familiar with BMW parts should perform the installation. The OS Giken LSD is the limited slip unit (or 'chunk') only. It replaces the stock non-LSD chunk but the original ring and pinion and other internals must be installed with the OS Giken unit. This unit will only work on 335i manual differentials with a bolt-in or modified ring gear. Proper setup and spacing is critical for long life operation. Incorrect installation will void the warranty. We also offer the TCD unit pre-installed - see our performance diff catalog for more info.

    The OS Giken TCD Diff unit fits the following BMWs:
    2008-2012 E82 BMW 135i with manual transmission
    2007-2011 E90 BMW 335i - Sedan with manual transmission
    2007-2013 E92 BMW 335i 335is - Coupe with manual transmission
    2007-2013 E93 BMW 335i - Convertible with manual transmission
    Part #: BM531-HC
    Price: $4964.90 (USD) 
    The OS Giken Super Lock LSD Gear Oil 80W-250 1 Liter FR is the OS Giken's very own special blend of gear oil which does an excellent job of lubricating and protecting your Super Lock LSD from failure. Through use of this high quality liquid, your Super Lock LSD will last much longer if regular oil changes are performed.

    Type: FULL SYNTHETIC
    SAE: 80W-250
    API: GL-5
    Flash point: 208℃
    Viscosity: 320.5(40℃), 43.7(100℃)
    Part #: OS250R
    Price: $49.95 (USD) 
    Quantity:   
    Made in the USA Over the years driving and racing the E46 M3 in Grand-Am racing, club racing, driving school events, and street driving, we have found that the half-shafts need to be rebuilt or replaced often. This is especially true of the outer CV joint (closest to the wheel bearing) due to the high loads on the half shafts and elevated temperature in that region. Thanks to our extensive experience in Grand-Am endurance racing, we have designed a kit to prolong CV joint life and save frequent and costly replacing of half shafts, on both street and track/race cars. The problem with rebuilding E46 half-shafts is that the CV joint ("Constant Velocity Joint") closest to the wheel bearing is not serviceable because a stamped steel housing must be cut off to access the CV joint. The housing cannot be reused, therefore necessitating replacement of the whole half-shaft. We have designed a reusable aluminum housing to make servicing the CV joint possible.

    This is a custom Turner Motorsport item, originally designed for our championship-winning Grand-Am M3s. It can also be used in non-racing applications, for both track and street E46 M3s. If you are performing any work on the rear driveline of your E46 M3 (such as wheel bearings, differential work, bushings, rear sway bar / swaybar, etc) or are prepping for the race season, then now is an excellent time to perform this job as well.

    Kit includes 2 CNC aluminum housings (left and right are the same) with Black anodized coating, 12 set-screws (6 per housing), 2 Viton O-rings, 8 Oetiker clamps, and 4 stainless steel breather tubes (only required for race use).

    Click for instructions click for intructions (PDF)
    Part #: TDR4628CVJ
    Price: $189.95 (USD) 
    Quantity:   
    The limited slip unit on the 2006+ M5 and M6 is designed to be a pure street car differential. It's simply not up to the rigors of professional or amateur racing. The OS Giken Super Lock LSD is giant step up in from a stock viscous limited-slip unit. It's ready for the extreme conditions of racing, offers 100% progressive locking capability, and is able to do this while operating smoothly and quietly. It's use of advanced technologies that make it perfect for both street cars AND pro race cars... and everything in between. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've been using them in our own Championship winning race cars.

    OS Giken incorporated revolutionary new ideas when developing the their own limited slip diff, utilizing their accumulated racing knowledge and experience and over 4 years of development. Their design uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The end result of their efforts is the OS Giken's OS Super Lock LSD which offers incredible durability and reliability on street and track driven BMWs. The use of highest quality materials, precise machining, forged gears and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). This is such a great design, in that it can be used in any situation -- whether it's for a street car, or a 100% Professional race car. Zero break-in required. Super smooth and quiet engagement, and 100% progressive locking capability. Professional installation is recommended.

    This Limited Slip Differential Unit fits the following BMWs:
    2006-2010 E60 M5 sedan
    2005-2011 E63 M6 coupe
    2005-2011 E64 M6 convertible
    Part #: BM237-HC
    Price: $2889.95 (USD) 
    Quantity:   
    The biggest shortcoming of any MINI is not the lack of power - it's being able to put all of its useable power to the ground! The Cooper S is basically a one-wheel drive car and sending 200+ hp through that one tire does not live up to its full potential. A limited-slip differential is essential to any highly-tuned FWD car. The OS Giken Super-Lock is one of the most advanced clutch-type differentials on the market, and a favorite of autocrossers and road racers. The OS LSD for the MINI features ten clutch discs for a smooth and progressive lockup. It's 1.5-way design provides stable power application under acceleration with an added bonus of moderate lock on decel too. By putting all of your available power to the ground you're at an instant advantage over the stock open-type differential. You'll be able to power through corners and on rough surfaces instead of uselessly spinning a wheel. Understeer is reduced by giving more bite to the tire that has the most traction. With an LSD in your MINI Cooper S you'll wonder why it wasn't first on your list to begin with (or why MINI/BMW left it out in the first place...).

    The MNI OS Giken LSD uses a special 80W250 fluid that must be purchased separately.

    This item fits the following BMWs:
    2002-2006 R53 MINI MINI Cooper S (6MT manual transmission only)
    2007-2013 R56 MINI MINI Cooper S (6MT manual transmission only)
    Part #: MN023-HA
    Price: $1789.00 (USD) 
    Quantity:   
    This is the front or rear Genuine BMW differential fluid drain plug for many BMWs. This can also be the transfer case plug or automatic transmission plug on some BMWs.

    + Year & Model Applications
    (click to expand)
    This item fits the following BMWs:
    1970-1976 2002 BMW 1600 2002 2002tii
    2008+ E82 BMW 128i 135i 1M Coupe
    1977-1983 E21 BMW 320i 323i
    1984-1991 E30 BMW 318i 318is 318ic 325e 325es 325i 325ic 325is 325ix M3
    1992-1998 E36 BMW 318i 318is 318ti 318ic 323is 323ic 325i 325is 325ic 328i 328is 328ic M3
    1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi M3
    2006-2011 E90 BMW 325i 325xi 328i 328xi 328i xDrive 330i 330xi 335d 335i 335xi 335i xDrive M3 - Sedan
    2006-2012 E91 BMW 325xi 328i 328xi 328i xDrive - Wagon
    2007-2012 E92 BMW 328i 328xi 328i xDrive 335i 335is 335xi 335i xDrive M3 - Coupe
    2007-2012 E93 BMW 328i 335i M3 - Convertible
    1976-1981 E12 BMW 528i 530i
    1982-1988 E28 BMW 524td 528e 533i 535i 535is M5
    1989-1995 E34 BMW 525i 530i 535i 540i M5
    1997-2003 E39 BMW 525i 528i 530i 540i M5
    2004-2010 E60 BMW 525i 525xi 530i 530xi 528i 528xi 528i xDrive 535i 535xi 535i xDrive 545i 550i M5
    2010+ F07 BMW 535i GT, 535i xDrive GT, 550i GT, 550i xDrive GT
    2011+ F10 BMW 528i 528i xDrive 535i 535i xDrive 550i 550i xDrive M5
    1982-1989 E24 BMW 633csi 635csi M6
    2004-2010 E63 BMW 645ci 650i M6
    2012+ F12 BMW 640i 650i
    1981-1987 E23 BMW 733i 735i
    1988-1994 E32 BMW 735i 735il 740i 740il 750il
    1995-2001 E38 BMW 740i 740il 750il
    2002-2008 E65 BMW 745i 745li 750i 750li 760i 760li
    2009+ F01 BMW 740i 740li 750i 750li 750i xDrive 750li xDrive 760li
    1990-1999 E31 BMW 840i 840ci 850i 850ci 850csi
    2004-2010 E83 BMW X3 2.5i X3 3.0i X3 3.0si
    2011+ F25 BMW X3 xDrive28i X3 xDrive35i
    2000-2006 E53 BMW X5 3.0i X5 4.4i X5 4.6is X5 4.8is
    2007-2013 E70 BMW X5 3.0si X5 4.8i X5 xDrive30i X5 xDrive35d X5 xDrive35i X5 xDrive48i X5M
    2008+ E71 BMW X6 xDrive35i X6 xDrive50i X6M
    1997-2002 Z3 BMW Z3 1.9 Z3 2.3 Z3 2.5i Z3 2.8 Z3 3.0i M Roadster M Coupe
    2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si Z4 M Roadster M Coupe
    2009+ Z4 BMW Z4 sDrive30i Z4 sDrive35i Z4 sDrive35is
    2000-2003 E52 BMW Z8 Roadster

    Part #: 33117525064
    Price: $6.95 (USD) 
    Quantity:   

    Used to create a seal on your differential where the axle shaft connects


    Genuine BMW Shaft Seal With Lock Ring - 100X50X10
    This item fits the following BMW Chassis:
    E53 48IS,E38,E39,E53 X5,E63,E65,E82,E89 Z4,E90,E92,E93
     

     

    Part #: 33107505605
    Price: $23.95 (USD) 
    Quantity:   
    Output Shaft Seal E36 M3, E39, E46 - does not fit E46 M3. this is the seal that is on the output side of the transmission.

    This item fits the following BMWs:
    1992-1998 E36 BMW 328i 328is 328ic M3
    1999-03/2003 E46 BMW 328i 328ci 330i 330ci
    1997-2003 E39 BMW 525i 528i 530i
    1997-2002 Z3 BMW Z3 2.8 Z3 3.0i M Roadster M Coupe
    Part #: 23111224799
    Price: $14.95 (USD) 
    Quantity:   
    As Used on our Project Mini Cooper S
    The Quaife torque biasing differential enables your car to accelerate quicker and corner faster. How? By getting the power to the ground! The Quaife Differential powers both drive wheels under nearly all conditions, instead of just one. With an ordinary open differential, standard on all MINI's, a lot of precious power is wasted during wheelspin under acceleration. This happens because the open differential shifts power to the wheel with less grip (along the path of least resistance). The Quaife, however, does just the opposite. It senses which wheel has the better grip, and biases the power to that wheel. It does this smoothly and constantly, and without ever completely removing power from the other wheel.
    Part #: TMS7
    Price: $1195.00 (USD) 
    Quantity:   

    One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

    Gearing Changes The 128i comes from the factory with a 3.23 ratio. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Click the banner below to see examples.
     

    2009 128i, 6-speed manual, 245/35-18" rear tires

    (click to expand)

    Gear RatioGearSpeedRPM

    40 MPH in 4th

    3.234th40 MPH2,150 RPM

    3.644th40 MPH2,400 RPM

    3.914th40 MPH2,550 RPM

    70 MPH Cruise

    3.236th70 MPH2,600 RPM

    3.646th70 MPH2,900 RPM

    3.916th70 MPH3,100 RPM

    5th Gear Speed @ 6,000 RPM

    3.235th138 MPH6,000 RPM

    3.645th123 MPH6,000 RPM

    3.915th114 MPH6,000 RPM

    These are just a range using three gear ratios (stock, middle, extreme). Speeds and RPM will obviously change in between ratios.
    Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.


    Limited Slip Options. The E82 128 did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%).
    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2008-2012 E82 BMW 128i

    Part #: TMS211213
    Price: $1724.00 (USD) 
    As Used on Project E36 M3
    Upgrading or rebuilding the differential is one of the keys to performance on your E36 325i/328i or E36 M3. Adding a shorter gear set will make the car accelerate quicker with almost no downside. And adding or changing the limited slip unit will improve traction and handling. The diff is crucial to getting the most out of popular engine upgrades such as an M50 manifold swap and cams where the new gear ratio will keep you in the power band sooner.

    Gearing Changes Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Refer to the chart below for examples.

    Gearing Charts:
    1997 M3, 5-speed manual, 245/40-17" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    3.234th40 MPH2,200 RPM
    3.464th40 MPH2,300 RPM
    3.644th40 MPH2,450 RPM
    70 MPH Cruise
    3.235th70 MPH3,100 RPM
    3.465th70 MPH3,300 RPM
    3.645th70 MPH3,450 RPM
    5th Gear Speed With Raised Rev Limit
    3.235th159 MPH7,000 RPM
    3.465th149 MPH7,000 RPM
    3.645th141 MPH7,000 RPM
    These are just a range using three gear ratios (stock, middle, extreme). Speeds and RPM will obviously change in between ratios. Speed in 5th gear at 7,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

    Limited Slip Options. If you're lucky enough to have an E36 with a factory limited slip differential we don't need to make too many changes. But we will rebuild it for you (you'll be amazed how much better the fresh LSD will perform). If you do not have an LSD already you will want to get one, especially if you're deleting the ASC+T traction control. If you only deleted the ASC and not using an LSD you're suffering from 'One Tire Fire' - all of your power goes through one wheel. The limited slip will balance the torque through both rear wheels before the one begins to spin (depending on the lock-up you choose). We offer limited-slip options that are similar to the factory 2 or 3 disc limited slip, Quaife helical style (no clutch packs), and OS Giken multi-disc variable LSD that our race team uses.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. There is a $400 charge for a factory LSD diff and a $200 for a factory non-LSD (open) diff. To make the process simple, all custom diff orders are charged $400 and the refund will be based on the diff that you send back. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This custom differential fits the following BMWs:
    1992-1998 E36 BMW 323is 323ic 325i 325is 325ic 328i 328is 328ic M3 (US model)
    Part #: TMS338680
    Price: $1924.00 (USD) 
    Changing the rear gearing on your 540i is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in a stronger part of the power band for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. And there is almost no downside!

    The stock 540i has either a 2.81 or 3.15 final drive ratio. Both are relatively tall (numerically low) because of the 540's torque output and 6-speed transmission. But using a shorter gear (numerically higher) will take advantage of that torque output even more and give dramatically better acceleration. We rebuild the stock BMW diff with the new gear ratio, new bearings, and new seals. So not only do you get a performance improvement but also a rebuild of a potentially troublesome component. We can also add a limited-slip unit to get better traction.

    By changing the gearing, you are changing the speed in relation to engine RPM. The 540i begins to make most of its torque at 2,700 RPM. With the original gear ratio, 25 MPH is 2nd gear at 2,500 RPM. With shorter 3.46 gearing at 25 MPH in 2nd you're now at 3,000 RPM - much deeper into the power band! At 70 MPH in 6th you are right at the start of the torque curve, which means you get much more thrust and maybe no need to downshift! Here are more examples of the gearing and speed differences -

    2002 E39 540i, 6-speed manual, 255/40-17" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    2.814th38 MPH1,750 RPM
    3.154th38 MPH2,000 RPM
    3.464th39 MPH2,250 RPM
    3.624th38 MPH2,250 RPM
    70 MPH Cruise
    2.816th72 MPH2,250 RPM
    3.156th71 MPH2,500 RPM
    3.466th71 MPH2,750 RPM
    3.626th68 MPH2,750 RPM
    5th Gear Speed at Redline
    2.815th159 MPH6,000 RPM
    3.155th142 MPH6,000 RPM
    3.465th129 MPH6,000 RPM
    3.625th123 MPH6,000 RPM
    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your 540 will top out at.

    Limited Slip Options The 540i did not come from BMW with a limited-slip differential (posi-traction). Instead, they relied on the throttle electronics and/or brake application to limit wheelspin. The problem with this system is that as soon as it detects wheelspin the electronics cut engine power first. On later models with DSC the brakes will also be applied to the spinning wheel. And without limited-slip (an 'open' diff) it means that power is really only being directed to one wheel (not both rear wheels) - the infamous 'One Tire Fire'. Lifting the inside wheel in a corner can result in useless wheel spin, then engine power cutoff, which is futile when trying accelerate out of a corner. Instead, a limited slip differential (LSD) will transfer power from the inside to the outside wheel that has a lot more traction. We can also vary how much torque is transferred (the 'lock-up') so that you can still transfer torque and get some wheelspin at the same time (great for drifting/autocross!).

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    1997-2003 E39 BMW 540i
    Part #: TMS20538
    Price: $1724.00 (USD) 
    A custom differential is one of the best, and smartest, upgrades to have done to your E39 M5. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

    Gearing The E39 M5 diff comes with a 3.15 gear ratio and relies on the torque of the motor for acceleration. But if you would like to get up into the torque curve sooner, this is your best bet. Which ratio you choose depends mainly on what your priorities are. If you use the car mostly for highway cruising the shorter ratios will result in higher RPM and worse fuel mileage. But the shorter ratios are better for around town driving where you want to be up into the torque curve more. Use the chart below for examples of the differences.

    2002 E39 M5, 275/35-18" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    3.154th39 MPH2,000 RPM
    3.454th40 MPH2,250 RPM
    3.734th41 MPH2,500 RPM
    70 MPH Cruise
    3.156th70 MPH2,400 RPM
    3.456th70 MPH2,650 RPM
    3.736th70 MPH2,875 RPM
    5th Gear Speed at Redline
    3.155th169 MPH7,000 RPM
    3.455th154 MPH7,000 RPM
    3.735th143 MPH7,000 RPM
    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M5 will top out at.

    Limited Slip Options The M5's M Variable locking differential is genius when it's working properly. Unfortunately, as many M5 (and M3) owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    1999-2003 E39 BMW M5
    Part #: TMS20537
    Price: $2799.00 (USD) 
    This Genuine BMW speedometer / pulse generator is mounted in the back of the differential and provides wheel speed information to the instrument cluster speedometer.

    This item fits the following BMWs:
    1987-1991 E30 BMW 325ix
    1992-1998 E36 BMW 318i 318is 318ti 318ic 323is 323ic 325i 325is 325ic 328i 328is 328ic M3
    1990-1999 E31 BMW 840i 840ci 850i 850ci 850csi
    1996-2002 Z3 BMW Z3 1.9 Z3 2.3 Z3 2.5i Z3 2.8 Z3 3.0i
    Part #: 62168357020
    Price: $30.95 (USD) 
    Quantity:   
    This is the differential cover gasket / diff seal for E30 3 series, 1984-1991.
    Part #: 33111210405
    Price: $4.95 (USD) 
    Quantity:   


    Hands down - one of the best performance upgrades you can make to an E46 M3, E60 M5 or E63/E64 M6! With almost no downside you can make your BMW much quicker by swapping in a new ring & pinion gear set. The gearing used to be overlooked when planning modifications but the 3.91 and 4.10 gears are now one of our biggest selling upgrades for the E46 M3! With a rear end gear upgrade you get the effects of adding horsepower but without adding any more stress to the engine or drivetrain. It's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration. The R&P acts as a torque multiplier, putting the engine into the power band sooner for each gear. There is an 8% increase in torque at the wheels with the shorter R&P. Want to make your car faster off the line or out of corners? Or avoid a downshift to pass on the highway? This is what you need.

    The R&P can be installed on its own but for cars that have more than 60,000 miles it would be a better idea to rebuild the whole diff. The factory viscous limited slip units have a typical lifespan of 50-70,000 miles. We offer diff rebuilding with 3.91 or other gear options and you get a fully-rebuilt and serviced limited slip unit at the same time. Click here for our diff rebuild options.

    3.91 Gearing Example: 2004 M3, 6-speed manual, 275/35-19" rear tires

     

    Gear RatioGearSpeedRPM

    40 MPH in 4th

    3.624th40 MPH2,250 RPM

    3.914th40 MPH2,450 RPM

    70 MPH Cruise

    3.626th70 MPH2,650 RPM

    3.916th70 MPH2,900 RPM

    5th Gear Speed at Redline

    3.625th175 MPH8,000 RPM

    3.915th162 MPH8,000 RPM

    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.


    This item is the genuine BMW part and the ring & pinion set only. You will need to have this professionally installed into your existing differential. BMW does not supply differential rebuild parts (bearings, shims, plates, etc.) so only a qualified shop that is experienced in BMW diff rebuilding should perform this installation. We also offer built differentials and exchanges, click here.

    This item fits the following BMWs:
    2001-2006 E46 BMW M3
    2004-2010 E60 BMW M5
    2004-2011 E63 BMW M6

    Part #: E46M3RP
    Price: $703.95 (USD) 
    $847.21 (17% off MSRP)
    Quantity:   
    BMW does not sell the differential mounts separate from the cover. And as with all rubber mounts, they will have to be replaced at some point, forcing you to also buy a new diff cover. This is an Original BMW part.
    **Note** - a paper gasket is not sold with this cover. BMW no longer uses paper gaskets - they advise the use of a silicone sealant such as RTV black.

    Applications:
    2001-2006 E46 M3, M3 CSL, coupe and convertible

    Part #: 33112282482
    Price: $184.95 (USD) 
    Quantity:   
    You use a magnetic drain plug for your engine oil, right? Why not apply the same proactive thinking to the differential too? This is a direct replacement magnetic differential drain plug for your BMW. It will catch and retain fine and larger metal particles in your diff oil. If you're proactive in your diff oil servicing, you will catch a minor issue long before it becomes a headache. Diff drain plug includes one sealing o-ring.
    Part #: 009314ECS01A
    Price: $19.95 (USD) 
    Quantity:   
    This factory finned differential cover bolts directly to the E30 diff housing. This is a must for track cars with limited slip differentials. The clutch packs in these diffs generate a lot of heat, the more heat you can dissipate the better. The fins on this cover will do just that. This is an inexpensive upgrade that may save you a lot of money down the road. Plus it looks cool.

    Kit includes cover, gasket and all necessary hardware.:
  • 1 x 33112228335 - Differential Cover
  • 1 x 33111210405 - Differential Gasket
  • 2 x 07119914114 - Bolt
  • 4 x 07119921522 - Bolt
  • 2 x 07119921541 - Bolt


    This item fits the following BMWs:
    1984-1991 E30 BMW 325e 325es 325i 325ic 325is M3
  • Part #: 33112228335KIT
    Price: $453.50 (USD) 
    Quantity:   
    Genuine Bmw Bmw M Performance Limited-Sl - 33108659987
    Part #: 33108659987
    Price: $2415.95 (USD) 
    Quantity:   
    A custom differential is one of the best upgrades to have done to your E60 M5 and M6. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

    Gearing The E60 M5 diff comes with a relatively short 3.62 gear ratio. They could use a shorter gear because the engine redline is so high - the car has a long power band and the gear spacing allows you to stay well within that range. There's always more acceleration to be had with a shorter gear set. BMW Motorsport supplies 3.91 or 4.10 options and there are other gear ratios to select in our custom builds. We sell a lot of 3.91 gear sets for the M5 because it works seamlessly with the SMG transmission. Other ratios may have issues with shifting, especially in full auto mode. Your speed vs RPM obviously changes with a different gear set. Use the chart below for examples of the differences.

    2008 E60 M5, 7-speed SMG, 285/35-19" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH In 4th
    3.624th40 MPH2,500 RPM
    3.914th40 MPH2,750 RPM
    4.104th40 MPH2,800 RPM
    70 MPH Cruise
    3.627th70 MPH2,600 RPM
    3.917th70 MPH2,875 RPM
    4.107th70 MPH3,000 RPM
    6th Gear Speed at Redline
    3.626th182 MPH8,250 RPM
    3.916th169 MPH8,250 RPM
    4.106th161 MPH8,250 RPM
    Why 6th? Because 7th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 6th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M5/M6 will top out at.

    Limited Slip Options The M5's M Variable locking differential is genius when it's working properly. Unfortunately, as many M3/M5/M6 owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2006-2010 E60 BMW M5
    2006-2010 E63 E64 BMW M6
    Part #: TMS21533
    Price: $2149.00 (USD) 
    The differential is one of the key components of any race car build. For the Spec E46 racing class the rules call for "3.46 gear ratio, factory housing, flanges, and mounting points. The internal parts of the differential are otherwise unrestricted, including the use of limited slip units." (as of September 2015). If you're not running one of these SE46 diffs you can expect to be passed by someone who is. The non-M E46 did not come with a limited slip so the benefits of using one are obvious - put down as much power as early as possible in the corner and gain more top speed on the straights. Don't sit and wait for your car to hook up in the corner while someone else has already gone by!

    Our ideal SpecE46 diff is built with these options: 3-disc limited slip with 30/90 ramp angles, polished gears and polished carrier bearings, and the race carrier (see below). This setup has been tested and developed extensively on E46 330 and E46 M3 racecars. The 30deg angle on acceleration will engage the clutch discs sooner than a factory or "standard" LSD and give you outstanding traction accelerating out of corners. The 90deg decel will not engage the clutches so the inside drive wheel will not be pushing the car straight while you are executing braking and turn-in. This diff also works great for other E46 track cars (not just SE46). We can also build the diff in a different way if you prefer more or less clutch discs or a different style of limited slip.

    A full race limited slip carrier option uses 6 clutch discs and coil springs for a completely tunable race diff. The coil springs inside the carrier control preload of the discs ensuring the limited slip is working consistently even as the discs wear. The spring tension and ramp angles can be customized for your preferences although there is a "hot setup" for SE46 cars already. The race carrier is also much lighter than the standard LSD units.

    If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2001-2006 E46 BMW 330i 330ci
    Part #: TMS221921
    Price: $1724.00 (USD) 
    Upgrading or rebuilding the differential is one of the keys to the performance of the E30 325 or E30 M3. The 325e had a very tall 2.79 or 2.93 final drive for fuel economy and because of its low rev limit. The 325i and 325is manual transmission models had a much snappier 3.73 rear end. The M3 came with the shorter 4.10 gearing. For most E30 owners the standard gearing is well-suited for the street. If the shorter 3.73/4.10 gearing is too high for daily driving you can swap to a taller gear for lower revs (better fuel economy, less noise). On the flip side, changing to a shorter gear can work in your favor for acceleration runs or if you find yourself at the wrong RPM for certain tracks. And if you have installed an M50/S50/S52 engine the gearing should be changed as well to make better use of the new torque curve.

    Gearing Changes Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Click the banners below to see how different ratios relate to particular speeds.

    Gearing Charts:
    E30 M20, Getrag 5-speed manual, 205/50-15" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    70 MPH Cruise
    3.465th70 MPH2,900 RPM
    3.735th70 MPH3,080 RPM
    3.915th70 MPH3,250 RPM
    4.105th70 MPH3,400 RPM
    Theoretical Top Speed With Raised Rev Limit
    3.735th154 MPH6,800 RPM
    3.915th147 MPH6,800 RPM
    4.105th141 MPH6,800 RPM
    These are just a range using a stock and a selection of alternative gear ratios. Speeds and RPM will obviously change in between ratios.
    Speed in 5th gear at 7000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.
    E30 M50, M3 ZF 5-speed manual, 225/50-15" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    70 MPH Cruise
    3.735th70 MPH3,750 RPM
    3.465th70 MPH3,400 RPM
    3.255th70 MPH3,250 RPM
    Theoretical Top Speed With Raised Rev Limit
    3.735th133 MPH7,000 RPM
    3.465th144 MPH7,000 RPM
    3.255th153 MPH7,000 RPM
    These are just a range using a stock and a selection of alternative gear ratios. Speeds and RPM will obviously change in between ratios.
    Speed in 5th gear at 7000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

    Limited Slip Options. If you're lucky enough to have an E30 with a factory limited slip differential we don't need to make too many changes. But we will rebuild it for you. If you do not have an LSD already you will want to get one, especially with an M50 swap. Without a limited-slip you're suffering from 'One Tire Fire' - all of your power goes through one wheel. The limited slip will balance the torque through both rear wheels before the one begins to spin (depending on the lock-up you choose). We offer limited-slip options that are similar to the factory 2 or 3 disc limited slip, Quaife helical style (no clutch packs), and OS Giken multi-disc variable LSD that our race team uses.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. There is a $400 charge for a factory LSD diff and a $200 for a factory non-LSD (open) diff. To make the process simple, all custom diff orders are charged $400 and the refund will be based on the diff that you send back. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This custom differential fits the following BMWs:
    1984-1991 E30 BMW 318i 318is 318ic 325e 325es 325i 325ic 325is M3
    Part #: TMS340133
    Price: $1824.00 (USD) 
    Changing the rear gearing on your E60 V8 is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in a stronger part of the power band for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. And there is almost no downside!

    The stock 545i or 550i with a manual transmission has a 2.81 final drive ratio. It's a relatively tall (numerically low) drive ratio because of the V8's torque output. But using a shorter gear (numerically higher) will take advantage of that torque output even more and give dramatically better acceleration. We rebuild the stock BMW diff with the new gear ratio, new bearings, and new seals. So not only do you get a performance improvement but also a rebuild of a potentially troublesome component. We can also add a limited-slip unit to get better traction.

    By changing the gearing, you are changing the speed in relation to engine RPM. The 545i begins to make most of its torque by 2,500 RPM. With the original gear ratio, 25 MPH is 2nd gear at 2,250 RPM. With shorter 3.46 gearing at 25 MPH in 2nd you're now at 2,750 RPM - much deeper into the power band! At 70 MPH in 6th you are right at the start of the torque curve, which means you get much more thrust and maybe no need to downshift! Here are more examples of the gearing and speed differences -

    2008 E60 550i, 6-speed manual, 275/30-19" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th
    2.814th40 MPH1,800 RPM
    3.154th40 MPH2,000 RPM
    3.464th41 MPH2,250 RPM
    3.914th41 MPH2,500 RPM
    70 MPH Cruise
    2.816th70 MPH2,350 RPM
    3.156th69 MPH2,500 RPM
    3.466th69 MPH2,750 RPM
    3.916th70 MPH3,150 RPM
    5th Gear Speed at Redline
    2.815th168 MPH6,500 RPM
    3.155th157 MPH6,500 RPM
    3.465th143 MPH6,500 RPM
    3.915th126 MPH6,500 RPM
    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your car will top out at.

    Limited Slip Options The 545i/550i did not come from BMW with a limited-slip differential (posi-traction). Instead, they relied on the throttle electronics and/or brake application to limit wheelspin. The problem with this system is that as soon as it detects wheelspin the electronics cut engine power first. On later models with DSC the brakes will also be applied to the spinning wheel. And without limited-slip (an 'open' diff) it means that power is really only being directed to one wheel (not both rear wheels) - the infamous 'One Tire Fire'. Lifting the inside wheel in a corner can result in useless wheel spin, then engine power cutoff, which is futile when trying accelerate out of a corner. Instead, a limited slip differential (LSD) will transfer power from the inside to the outside wheel that has a lot more traction. We can also vary how much torque is transferred (the 'lock-up') so that you can still transfer torque and get some wheelspin at the same time (great for drifting/autocross!).

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2004-2010 E60 BMW 545i 550i manual transmission
    Part #: TMS21534
    Price: $1924.00 (USD) 
    One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels but may induce an understeer condition (too much power pushing the car straight); a variable lock-up will give you the optimum balance. Our experience in diff building, car prep, and racing will ensure we get you the correct custom build for your specific driving conditions.

    Gearing Changes All of the 335is DCT differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 2.81 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the 2.81 is currently the only gear option offered at this time but it's perfect for keeping the N54 engines on the boost. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. The higher ratio puts you at a higher RPM point for any given speed. This puts you further up in the power band, giving you more torque to the ground. Refer to the chart below for examples on the difference.

    2011 335is, 7-speed DCT, 255/30-19" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    40 MPH in 4th or 5th
    2.564th39 MPH2,250 RPM
    2.814th39 MPH2,500 RPM
    2.565th40 MPH1,900 RPM
    2.815th40 MPH2,100 RPM
    70 MPH Cruise
    2.567th70 MPH2,407 RPM
    2.817th70 MPH2,642 RPM
    5th Gear Speed @ 7,000 RPM
    2.565th146 MPH7,000 RPM
    2.815th135 MPH7,000 RPM
    Speed in 5th gear at 7,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

    Limited Slip Options. The 335is sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. We offer several types of limited slip units for the 335is:
  • traditional 2 or 3-disc LSD (40-60% fixed lock-up)
  • 3-disc LSD with variable ramp angles (user-variable lock-up)
  • Quaife helical (no clutch discs)
  • OS Giken Superlock multi-plate LSD (0-100% lock-up)
  • OS Giken TractionControlDiff multi-plate LSD (0-100% lock-up) (smoother and quieter version of Superlock)
    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2011-2012 E82 BMW 135i with DCT transmission
    2011-2013 E92 E93 BMW 335is with DCT transmission
  • Part #: TMS208402
    Price: $2824.00 (USD) 

    This is a complete differential to change the gearing of a manual transmission E90/E92 325i, 328i, or 330i (not for xi models) to a 3.64 ratio final drive. The standard gearing on the manual transmission cars is 3.15 or 3.23, making this E90 diff significantly shorter. This diff is from a 330i automatic where the gear ratio has to be shorter to make up for the transmission gearing differences and extra weight. This will dramatically improve acceleration on any 325i, 328i or 330i INSTANTLY! If you are looking for better off-the-line or rolling acceleration, and are willing to sacrifice a little top-speed (some of us don't get up to 150mph), this is one of the best ways to achieve it with almost no downside. There are few things that can improve your 0-to-60 and 0-to-100 times as much as shorter gearing, and this differential is clearly a best "bang-for-buck" solution for dramatically better acceleration. Since this is an Original BMW part it carries the same BMW two year warranty as any other new part. So there's no need to take a chance on a used part from a private seller. (former BMW part number 33107519944)

    Changing gear ratio changes the RPM range for any given speed. Use the chart below for examples of speed vs RPM changes for the 3.64 diff.
     

    2006 330i, 6-speed manual, stock 3.15 gears, 255/35-18" rear tires

    Gear RatioGearSpeedRPM

    40 MPH in 4th

    3.154th40 MPH2,100 RPM

    3.644th40 MPH2,400 RPM

    70 MPH Cruise

    3.156th70 MPH2,500 RPM

    3.646th70 MPH2,900 RPM

    5th Gear Speed @ 6,000 RPM

    3.155th142 MPH6,000 RPM

    3.645th123 MPH6,000 RPM

    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your E90 will top out at.2006-2011 325i or 328i, 6-speed manual, stock 3.23 gears, 255/35-18" rear tires

    (click to expand)

    Gear RatioGearSpeedRPM

    40 MPH in 4th

    3.234th40 MPH2,150 RPM

    3.644th40 MPH2,400 RPM

    70 MPH Cruise

    3.236th70 MPH2,600 RPM

    3.646th70 MPH2,900 RPM

    5th Gear Speed @ 6,000 RPM

    3.235th138 MPH6,000 RPM

    3.645th123 MPH6,000 RPM

    Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.


    A $100 refundable core charge must be added at the time of order. This core charge can be refunded when you ship your original diff back to us.

    This item fits the following BMWs with manual transmission only:
    2006-2011 E90 BMW 325i 328i 330i - Sedan
    2006-2012 E91 BMW 325i 328i - Wagon
    2007-2013 E92 BMW 328i - Coupe
    2007-2013 E93 BMW 328i - Convertible

    Part #: 33107566176
    Price: $2132.95 (USD) 
    A custom differential is one of the most-effective upgrades to have done to your E82 1M Coupe. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top projects to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit.

    Gearing The 1M gearing is a relatively tall 3.15 from the factory. Using a shorter gear (numerically higher) ratio will give you better acceleration and put you in the boost sooner. The N54 engine begins to deliver serious torque around 2,200 RPM. Check out the chart below - 3.45 gearing would put you right at the start of peak torque production at 40 MPH in 4th gear! You have to be careful with your gearing selection though as too short of a gear will bring you to the rev limit sooner. And torque and power both drop off significantly past 5,500 RPM. Your speed vs RPM obviously changes with a different gear set. Use our chart below to accurately select a gear ratio that best suits your needs and driving style.

    Gearing Chart:
    2012 1M, 6-speed manual, 265/35-19" rear tires
    (click to expand)
    Gear RatioGearSpeedRPM
    4th Gear @ 40 MPH
    3.154th40 MPH1,900 RPM
    3.454th40 MPH2,100 RPM
    3.734th40 MPH2,250 RPM
    70 MPH Cruise
    3.156th70 MPH2,400 RPM
    3.456th70 MPH2,625 RPM
    3.736th70 MPH2,800 RPM
    5th Gear Speed at Redline
    3.155th174 MPH7,000 RPM
    3.455th159 MPH7,000 RPM
    3.735th147 MPH7,000 RPM
    Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.

    Limited Slip Options The 1M shares its M Variable locking differential with the M3. It's genius when it's working properly. Unfortunately, as many 1M/M3/M5/M6 owners have come to find, the system only has a service life of 80,000 miles (sometimes less) and then the viscous unit inside starts to fail (is your's clunking?). We can rebuild the internals and bring it back to a perfectly-functioning viscous M Variable unit. Or you may choose to lose the variable lock in favor of a traditional clutch-type or helical diff with a set locking. We also build diffs with Quiafe, Kaaz, and OS Giken (favorite of the Turner racing team) limited slip units.

    Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

    FAQ: For a full FAQ on the custom diff process, click here.

    This item fits the following BMWs:
    2011-2013 E82 BMW 1M Coupe
    Part #: TMS20542
    Price: $3399.00 (USD) 
    The 3.46 differential is an Original BMW part and a complete, fully-built differential ready to be bolted in to your E46 3-series or Z4 Roadster/Coupe. The 3.46 ratio was standard on most E46s and Z4s with an automatic transmission. The manual transmission cars came with 2.93 or 3.07 gear sets while automatics got shorter gears to make up for the difference in transmission ratios and extra weight of the transmission. Having the shorter ratio will put you in a better part of the RPM band for any given speed. This makes the car instantly quicker with more power and torque on tap. There's almost no downside aside from the higher revs will decrease fuel economy.

    Since this is an Original BMW part it carries the same BMW two year warranty as any other new part. So there's no need to take a chance on a used part from a private seller. Note: depending on the model and your existing diff, you may need to change the output flanges to match the set you currently use. Swapping from your old diff to the new one is acceptable.

    Examples: 2002 330i, 5-speed manual, 245/40-17" rear tires
    Gear RatioGearSpeedRPM
    2.934th40 MPH2,000 RPM
    3.464th40 MPH2,300 RPM
    2.935th70 MPH2,800 RPM
    3.465th70 MPH3,300 RPM
    3.465th128 MPH*6,000 RPM
    * - Theoretical speed for 3.07 gears at 6,000 RPM. It doesn't mean this speed is actually attainable. It's only offered for reference.

    This item fits the following BMWs:
    1999-2006 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi, with manual transmission
    2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si, with manual transmission

    Includes $100.00 core charge to be refunded on return of your rebuildable core.

    Part #: 33107531625
    Price: $1666.95 (USD) 
    Quantity:   
    The 3.64 differential is an Original BMW part and a complete, fully-built differential ready to be bolted in to your E46 3-series or Z4 Roadster/Coupe. The 3.64 ratio was standard on the Z4 2.5 automatic, which makes this an upgrade for both E46 automatic and SMG and Z4 3.0 automatic and SMG. It's also a big upgrade on all E46 and Z4 manual transmission cars as they came with 2.93 or 3.07 gear sets. The 3.64 is a huge 18-24% shorter than the stock 2.93 or 3.07. Having the shorter ratio will put you in a better part of the RPM band for any given speed. This makes the car instantly quicker. Since this is an Original BMW part it carries the same BMW two year warranty as any other new part. So there's no need to take a chance on a used part from a private seller. There's almost no downside! Note: depending on the model and your existing diff, you may need to change the output flanges to match the set you currently use. Swapping from your old diff to the new one is acceptable.

    Examples: 2002 330i, 5-speed manual, 245/40-17" rear tires
    Gear RatioGearSpeedRPM
    2.934th40 MPH2,000 RPM
    3.644th40 MPH2,450 RPM
    2.935th70 MPH2,800 RPM
    3.645th70 MPH3,450 RPM
    3.645th121 MPH*6,000 RPM
    * - Theoretical speed for 3.07 gears at 6,000 RPM. It doesn't mean this speed is actually attainable. It's only offered for reference.

    This item fits the following BMWs:
    1999-2006 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi
    2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si, Z4 2.5 = manual transmission only

    Includes $100.00 core charge to be refunded on return of your rebuildable core.

    Part #: 33107514198
    Price: $1766.17 (USD) 
    Quantity:   
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