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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.

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ECS - Corporate Logo
T#:378193
Part#: 002447ECS03KT
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Worn rubber differential mounts will lead to the differential twisting and shifting around in the rear subframe. Not only will this be noisy but it's bad for driver confidence and bad for the chassis as well. Even on fresh rubber bushings the differential has deflection and twist, especially if the car has been modified for more torque. Since the differential is centrally mounted in the rear subframe, with all suspension mounts interconnected, a differential with too much deflection will affect handling and could even damage the rear subframe.

These 88A urethane E46 M3 diff mounts are much stiffer than stock but still not as solid as our Turner aluminum/Delrin bushings. This set will resist twisting much better than the stock rubber mounts. Included is the front diff mount and two rear mounts in the cover.

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ECS - Corporate Logo
T#:589555
Part#: 026709ECS09
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Upgrade your worn OE rubber bushings with ECS Tuning's Performance Polyurethane Differential Bushing Set. In-House Engineered to improve power delivery and handling, with a superior service life over the soft factory rubber bushings.
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ECS - Corporate Logo
T#:596679
Part#: 026711ECS09
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This product was last offered at the strikethrough price on
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$ 169.09 USD
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Upgrade your worn rubber bushings with ECS Tuning's Performance Polyurethane Differential Bushing Set. In-House Engineered to improve power delivery and handling, with a superior service life over the soft factory rubber bushings.
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ECS - Corporate Logo
T#:348998
Part#: 002447ECS01
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Revitalize your driving experience with ECS Tuning's In-House Engineered Performance Polyurethane Differential Bushings. Say goodbye to soft factory rubber bushings and their deflection. These innovative bushings provide a substantial improvement in the connection between your right foot, the chassis, and the wheels. The outcome is a crisper power transfer from the differential to the wheels, resulting in enhanced throttle control for various driving activities. Notably, these polyurethane bushings achieve these benefits without the harshness or vibration often linked to delrin or solid differential mounts.

Manufactured using a robust 88A durometer polyurethane and a black anodized 6061-T6 aluminum sleeve, these bushings offer superior resistance to chemicals, ozone degradation, road salt, and general wear and tear. This translates to an extended service life.

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ECS - Corporate Logo
T#:378192
Part#: 002447ECS02KT
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Worn rubber differential mounts will lead to the differential twisting and shifting around in the rear subframe. Not only will this be noisy but it's bad for driver confidence and bad for the chassis as well. Even on fresh rubber bushings the differential has deflection and twist, especially if the car has been modified for more torque. Since the differential is centrally mounted in the rear subframe, with all suspension mounts interconnected, a differential with too much deflection will affect handling and could even damage the rear subframe.

These 88A urethane E46 diff mounts are much stiffer than stock but still not as solid as our Turner aluminum/Delrin bushings. This set will resist twisting much better than the stock rubber mounts. Included are the two front diff mounts and the rear mount in the cover.

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ECS - Corporate Logo
T#:589549
Part#: 26696ECS09
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$ 328.49 USD
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Differential bushings are responsible for keeping your rear end planted during the delivery of power to the rear wheels. As these bushings age, they wear out and should be replaced. If you ever see your bushings are cracked, it is time to replace them. By eliminating the drivetrain deflection that factory rubber bushings permit, throttle response is improved, and the tendency for a car to “Wheel Hop” is significantly reduced. Upgrade to ECS Poly Diff Bushings and feel the difference!
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ECS - Corporate Logo
T#:638460
Part#: 026809ECS10KT
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$ 177.50 USD
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Differential bushings are responsible for keeping your rear end planted during the delivery of power to the rear wheels. As these bushings age, they wear out and should be replaced. If you ever see your bushings are cracked, it is time to replace them. By eliminating the drivetrain deflection that factory rubber bushings permit, throttle response is improved, and the tendency for a car to “Wheel Hop” is significantly reduced. Upgrade to ECS Poly Diff Bushings and feel the difference!
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ECS - Corporate Logo
T#:341288
Part#: 002447ECS01KT
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Urethane mounts keep the differential from twisting under load. As torque is put through the driveline it causes anything to twist and move. The differential is mounted to the subframe and the twisting and deflection can be transferred to the rest of the chassis. With a stiffer mount the differential will not deflect as much. This improves seat-of-the-pants feeling to the driver, giving more feedback for smoother power delivery. In theory, there's also more torque being sent to the drive wheels since it's not being used up shifting the diff weight around.

These are tough 88A durometer urethane bushings with a anodized almunum center sleeve, engineered by ECS. This is a set of E36 diff bushings - 1 for the front and 2 for the rear cover. New high-grade hardware is included (the front bolt has a tendency to snap from all that torque twisting!).

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ECS - Corporate Logo
T#:638439
Part#: 026809ECS09KT
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$ 167.80 USD
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Differential bushings are responsible for keeping your rear end planted during the delivery of power to the rear wheels. As these bushings age, they wear out and should be replaced. If you ever see your bushings are cracked, it is time to replace them. By eliminating the drivetrain deflection that factory rubber bushings permit, throttle response is improved, and the tendency for a car to “Wheel Hop” is significantly reduced. Upgrade to ECS Poly Diff Bushings and feel the difference!
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Premium Differential Service Kit - E46 M3, E9X M3, E82 1 M Coupe ...
Includes BMW SAF-XJ limited slip differential fluid with FM booster
Packaged by Turner - Corporate Logo
T#:598688
Part#: E46M3DIFSERTMSKT
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Servicing your differential is an important job and should only be completed using high quality components! To ensure our customers are getting exactly what they need, we have put together this limited-slip differential service kit that includes all new fluid from BMW, a new BMW drain plug, and one of our new Titanium Magnetic Differential Drain Plugs!
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ECS - Corporate Logo
T#:656153
Part#: 026696ECS10
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$ 188.79 USD
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Differential bushings are responsible for keeping your rear end planted during the delivery of power to the rear wheels. As these bushings age, they wear out and should be replaced. If you ever see your bushings are cracked, it is time to replace them. By eliminating the drivetrain deflection that factory rubber bushings permit, throttle response is improved, and the tendency for a car to “Wheel Hop” is significantly reduced. Upgrade to ECS Poly Diff Bushings and feel the difference!
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ECS - Corporate Logo
T#:378219
Part#: 002447ECS04KT
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Sale - Save 25% $ 112.99

This product was last offered at the strikethrough price on
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$ 84.74 USD
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This product was last offered at the strikethrough price on
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$ 84.74 USD
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Your rear differential is indirectly connected to your right foot through the engine and driveline, and connected to the seat of your pants through the chassis. Soft factory rubber differential bushings absorb vibrations between chassis and differential, providing comfort and softness in both of these connections.

Enter ECS Tuning's In-House Engineered Performance Polyurethane Differential Bushings. By eliminating the deflection factory rubber bushings permit, the connection between your right foot (and your seat) to the wheels is improved. Removal of this slop allows for crisper power transfer from differential to wheels, which means better throttle control while carving a canyon road, drag racing, sliding the rear end out, or just driving to work. This is achieved without the harshness or vibration associated with delrin or solid differential mounts.

Featuring a tough 88A durometer polyurethane and Black anodized 6061-T6 aluminum Sleeve, our Performance Polyurethane Differential Bushings are more resistant to chemicals, ozone degradation, road salt, and general wear and tear than factory rubber bushings, resulting in a longer service life.

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ECS - Corporate Logo
T#:384597
Part#: 002447ECS01KT1
In Stock
Sale - Save 25% $ 148.99

This product was last offered at the strikethrough price on
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$ 111.74 USD
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Sale - Save 25%
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This product was last offered at the strikethrough price on
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$ 111.74 USD
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Your E36's rear differential is indirectly connected to your right foot through the engine and driveline, and connected to the seat of your pants through the chassis. Soft factory rubber differential bushings absorb vibrations between chassis and differential, providing comfort and softness in both of these connections. ECS Tuning's In-House Engineered Performance Polyurethane Differential Bushing eliminate deflection permitted by factory bushings, improving the connection you feel to your differential. Removal of this slop allows for crisper power transfer from differential to wheels, which means better throttle control while carving a canyon road, drag racing, sliding the rear end out, or just driving to work. This is achieved without the harshness or vibration associated with delrin or solid differential mounts. Featuring a tough 88A durometer polyurethane and Black anodized 6061-T6 aluminum Sleeve, our Performance Polyurethane Differential Bushings are more resistant to chemicals, ozone degradation, road salt, and general wear and tear than factory rubber bushings, resulting in a longer service life.
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Packaged by Turner - Corporate Logo
T#:556968
Part#: 33112282482KT3
Ships on Aug 28, 2026
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This kit includes Turner Motorsport solid aluminum differential race mounts pre installed in the differential cover for a quick install. These mounts where developed by Turner Motorsport for their Grand-Am Cup E46 M3 race cars, the advantages of solid aluminum mounts is increased suspension & drivetrain response, less drivetrain loss resulting in more wheel horsepower, and longevity - they effectively last forever. These CNC-machined mounts are a direct replacement for the stock rubber pieces, and have been lightened to remove excess weight. 

 

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Genuine BMW - Corporate Logo
T#:338092
Part#: 33107566176
Ships in 7 Business Days
Starting at $ 2,412.29 USD
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Starting at $ 2,412.29 USD
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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

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