BMW Differential and Gearing Upgrades for BMW 3 Series E46 (1999-2005)

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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#:348998
Part#: 002447ECS01
In Stock
Sale - Save 25% $ 148.99

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$ 111.74 USD
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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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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
In Stock
Sale - Save 25% $ 183.99

This product was last offered at the strikethrough price on
06-13-2026

$ 137.99 USD
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Sale - Save 25%
$ 183.99

This product was last offered at the strikethrough price on
06-13-2026

$ 137.99 USD
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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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Revshift - Corporate Logo
T#:582011
Part#: PDBE46MGREEN
Ships in 2 Business Days
$ 109.99 USD
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$ 109.99 USD
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Revshift polyurethane differential bushings completely replace the OEM rubber bushings on the E46 M3 and Z4M. These bushings stiffen the differential, improving the vehicle's handling capabilities and eliminating drive-line slop.
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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
In Stock
Sale - Save 8% $ 301.99

This product was last offered at the strikethrough price on
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$ 277.83 USD
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Sale - Save 8%
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This product was last offered at the strikethrough price on
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$ 277.83 USD
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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#:378219
Part#: 002447ECS04KT
In Stock
Sale - Save 25% $ 112.99

This product was last offered at the strikethrough price on
06-13-2026

$ 84.74 USD
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Sale - Save 25%
$ 112.99

This product was last offered at the strikethrough price on
06-13-2026

$ 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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Revshift - Corporate Logo
T#:1105905
Part#: PDB-E4695A
Special Order: No Guaranteed ETA
$ 129.99 USD
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$ 129.99 USD
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Utilizing high-precision machining technologies and their very own Polyurethane Manufacturing Department, every Revshift product is designed, manufactured, and tested in-house at their Detroit, Michigan facility.
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Powerflex Black Series - Corporate Logo
T#:379935
Part#: PFR5-4625BX2
Ships in 1 Business Day
$ 107.99 USD
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$ 107.99 USD
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Differential bushings are responsible for keeping the differential in solid alignment while dampening drivetrain vibration. While OE rubber bushings are fine when they are new from the factory, aged and worn out rubber bushings create a multitude of issues that can range from annoying to dangerous. As a factory bushing ages, it begins to harden and become brittle. When this happens the bushing will actually shrink and allow for movement at the differential mounting point. At this point, the differential is free to shift under load causing a noticeable clunking noise under acceleration and deceleration and massively increasing the stress on the driveshaft and axles. Manual transmissions suffer the worst from this as it can make shifting difficult since the differential will shift when the clutch is engaged and disengaged.

By replacing these bushings with full polyurethane, the movement is eliminated since the mounting point is supported by a much stiffer material that will not harden or shrink over time. This means less stress on the driveshaft and axles and greater longevity of supporting components. 

Powerflex Black Series bushings are the ultimate in track and race bushings. Featuring 95A durometer polyurethane, Black Series bushings are 25% stiffer than street bushings. Engineered to perform, Powerflex performance polyurethane control arm bushings offer a supreme level of control, while still providing enough comfort for the street, with advanced polyurethane that reduces NVH that often accompanies lesser bushings. Expect improved acceleration response, more direct shifting feel and overall improved drivetrain composure with Powerflex performance polyurethane bushings.

Poweflex is a leading manufacturer of aftermarket suspension bushings. Using state of the art design and manufacturing, all replacement bushings are engineered to out-perform and out-last the ones that came in the car. Each line of bushings is meticulously tested and then re-tested to ensure perfect fitment and enduring quality through the life of the vehicle. A full lifetime warranty backs every one of their products and demonstrates the level of confidence and commitment Powerflex has to their customers. 

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Packaged by Turner - Corporate Logo
T#:401688
Part#: 33117512980KT
Ships in 3 Business Days
$ 367.99 USD
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$ 367.99 USD
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The perfect upgrade for any E46, this finned differential cover increases cooling to the rear differential to prevent over heating and possible damage. This is a complete kit including fluid and drain plugs.

Includes the following

  • Aluminum finned differential cover
  • Drain & fill plug with sealing o-ring
  • 2 Quarts of Redline 75w90
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Packaged by Turner - Corporate Logo
T#:556968
Part#: 33112282482KT3
Ships in 10 Business Days
Sale - Save 7% $ 676.14

This product was last offered at the strikethrough price on
05-03-2026

$ 627.61 USD
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Sale - Save 7%
$ 676.14

This product was last offered at the strikethrough price on
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$ 627.61 USD
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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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IRP - Individual Racing Parts - Corporate Logo
T#:587020
Part#: IRPDB-46MAL
Special Order: No Guaranteed ETA
$ 151.99 USD
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$ 151.99 USD
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These aluminum mounts are a direct replacement for the stock rubber bushings and have been lightened to remove excess weight. Using aluminum instead of rubber eliminates the "wind up" inherent in rubber mounts, and this deflection slows suspension & drivetrain response. The tradeoff is an increase in NVH. Features: Stiffens chassis/Improves stability Less wear of other components Better durability Provides better control of chassis geometry Replaces OE: 33172282484 Recommended for racing use only Includes: 2 rear aluminum bushing 1 front aluminum bushings
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