Turner Custom Limited Slip Differentials - E8X

A custom differential is one of the best upgrades to have done to your BMW. Not only can you get more performance but you can also get rid of the open diff in non M BMWs or 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.
Sort By:

E82 128i Differential Upgrade - Custom Options
Diffs by Turner - Corporate Logo
T#:340215
Part#: TMS211213
Direct Ship, Expected Ship Date: Jun 29, 2021
Starting at $1,999.00
Free Shipping
Starting at $1,999.00
Free Shipping

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

Show More Show Less
E82 135i DCT Limited Slip and Gearing Differential Upgrade
Diffs by Turner - Corporate Logo
T#:340217
Part#: TMS211251
Direct Ship, Expected Ship Date: Jun 29, 2021
Starting at $2,399.00
Free Shipping
Starting at $2,399.00
Free Shipping
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
Show More Show Less
E82 135i Manual Limited Slip and Gearing Differential Upgrade
Diffs by Turner - Corporate Logo
T#:340218
Part#: TMS21529
Direct Ship, Expected Ship Date: Jun 29, 2021
Starting at $1,999.00
Free Shipping
Starting at $1,999.00
Free Shipping
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)
Show More Show Less

E82 135i Auto Limited Slip Differential Upgrade
Diffs by Turner - Corporate Logo
T#:340216
Part#: TMS21530
Direct Ship, Expected Ship Date: Jun 29, 2021
Starting at $2,199.00
Starting at $2,199.00
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)
Show More Show Less

E82 1M Differential Upgrade - Custom Options
Diffs by Turner - Corporate Logo
T#:340220
Part#: TMS20542
Direct Ship, Expected Ship Date: Jun 29, 2021
Starting at $2,999.00
Free Shipping
Starting at $2,999.00
Free Shipping
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
Show More Show Less