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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Turner Motorsport - Corporate Logo
T#:337
Part#: TDR4680035
Ships in 7 Business Days
Sale - Save 25% $ 232.99

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

$ 174.74 USD
Free Shipping
Sale - Save 25%
$ 232.99

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

$ 174.74 USD
Free Shipping
Made in the USA For our Grand-Am Cup E46 M3s we wanted a fully solid differential mount setup. The advantages of a fully-solid aluminum set is that they last forever, quickens response in the suspension, and frees up horsepower to the wheels. These fully solid aluminum diff mounts are CNC machined and lightened for a direct replacement of the original rubber pieces.

By substituting aluminum for rubber we can take out all of the deflection and 'wind up' inherent to the original rubber pieces. The high deflection rate of the stock rubber means the suspension reacts slower as the bushing is compressed. The power used to compress that bushing is instead passed straight to the axles and wheels. And since there is no time lost to deflection, response is greatly improved. These diff mounts are only recommended for racecars since the aluminum transfers more noise and vibration.

This is a 3-piece set with a single front bushing and two rear bushings to press into the cover. They mount with the stock BMW hardware.

This item fits the following BMWs:
2001-2006 E46 BMW M3
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Turner Motorsport - Corporate Logo
T#:555025
Part#: TDR4680035-01
Ships on Aug 28, 2026
Sale - Save 28% $ 597.46

This product was last offered at the strikethrough price on
06-14-2026

$ 432.64 USD
Free Shipping
Sale - Save 28%
$ 597.46

This product was last offered at the strikethrough price on
06-14-2026

$ 432.64 USD
Free Shipping
For our Grand-Am Cup E46 M3s we wanted a fully solid differential mount setup. The advantages of a fully-solid aluminum set is that they last forever, quickens response in the suspension, and frees up horsepower to the wheels. These fully solid aluminum diff mounts are CNC machined and lightened for a direct replacement of the original rubber pieces.

By substituting aluminum for rubber we can take out all of the deflection and 'wind up' inherent to the original rubber pieces. The high deflection rate of the stock rubber means the suspension reacts slower as the bushing is compressed. The power used to compress that bushing is instead passed straight to the axles and wheels. And since there is no time lost to deflection, response is greatly improved. These diff mounts are only recommended for racecars since the aluminum transfers more noise and vibration.

This is a 3-piece set with a single front bushing to be pressed in and two rear bushings pre-pressed into the cover. They mount with the stock BMW hardware.

This item fits the following BMWs:
2001-2006  E46 BMW  M3
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Powerflex - Corporate Logo
T#:378993
Part#: PFR5-4625X2
Ships in 9 Business Days
$ 94.99 USD
Free Shipping
$ 94.99 USD
Free Shipping

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 street bushings are ideal for street driven vehicles and those that see occasional autocross or track time. Need bushings for a dedicated track car? 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 steering feel, turn in, more responsive handling and overall improved chassis composure with Powerflex performance polyurethane control arm 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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