BMW Differential and Gearing Upgrades for BMW Z Series E85/6 (2003-2008)

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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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Powerflex - Corporate Logo
T#:378993
Part#: PFR5-4625X2
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$ 94.99 USD
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$ 94.99 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 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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Genuine BMW - Corporate Logo
T#:59643
Part#: 33173449082
Ships in 1 day
13% off MSRP $ 83.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 72.99 USD
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13% off MSRP
$ 83.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 72.99 USD
Free Shipping on orders $49 and up

Bushings tends to wear over time and split or even break free from the internal sleeve, causing excessive movement and sloppy control feel. Genuine BMW bushings are the perfect option to restore suspension back to day 1 quality.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform!


Genuine BMW Rubber Mounting Rear -
This item fits the following BMW Chassis:
E83 X3,E85,E86,E89 Z4

 

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Genuine BMW - Corporate Logo
T#:1095
Part#: 33117512980
Ships in 1 day
1% off MSRP $ 280.76

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 277.63 USD
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1% off MSRP
$ 280.76

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 277.63 USD
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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)
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Genuine BMW - Corporate Logo
T#:174741
Part#: 33137600693
Ships in 1 day
$ 16.99 USD
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Genuine BMW Dustcover Plate.

Genuine BMW - Corporate Logo
T#:360865
Part#: 33176770788
Ships in 1 day
4% off MSRP $ 27.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 26.99 USD
Free Shipping on orders $49 and up
4% off MSRP
$ 27.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 26.99 USD
Free Shipping on orders $49 and up
Genuine BMW - Corporate Logo
T#:25596
Part#: 33176770866
Ships in 1 day
13% off MSRP $ 83.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 72.99 USD
Free Shipping on orders $49 and up
13% off MSRP
$ 83.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 72.99 USD
Free Shipping on orders $49 and up


Genuine BMW Rubber Mounting Rear -
This item fits the following BMW Chassis:
E82,E83 X3,E85,E86,E90,E92,E93


Genuine BMW - Corporate Logo
T#:59553
Part#: 33137840564
Ships in 1 day
1% off MSRP $ 189.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 188.99 USD
Free Shipping on orders $49 and up
1% off MSRP
$ 189.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 188.99 USD
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Genuine BMW Drive Flange, Output, Right
This item fits the following BMW Chassis:
E46 M3,E85 Z4M,E46,E85 Z4,E86 Z4

Corteco - Corporate Logo
T#:593696
Part#: 01037027B
No longer available
No longer available
This seal is on the back of your transmission for the front to rear propeller or driveshaft.

Genuine BMW - Corporate Logo
T#:107
Part#: 33107514198
Ships in 3 Business Days
$ 2,680.99 USD
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$ 2,680.99 USD
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Price includes $100.00 core charge.

Genuine BMW - Corporate Logo
T#:1002353
Part#: E46M3DIFSER1KT
Ships on Sep 22, 2026
$ 287.99 USD
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$ 287.99 USD
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Elring - Corporate Logo
T#:44733256
Part#: 703.190
Special Order: No Guaranteed ETA
$ 34.99 USD
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If your differential is leaking fluid from the input shaft at the front of the diff case, there is a good chance this seal is faulty. Replace your leaking seal with this new seal from Elring to prevent further fluid loss and prevent damage to your differential. Replaces BMW p/n 33121213949, 33121212197, & 33121204847
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Front Differential Bushing - Priced Each
We Price Match - Give Us A Call or Chat!
Meyle - Corporate Logo
T#:36032352
Part#: 33176770788
Special Order: No Guaranteed ETA
$ 15.99 USD
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The subframe serves as the mounting point for your rear suspension, connecting to the vehicle's body with bushings designed to absorb vibrations. These bushings minimize vibrations transmitted to the cabin while maintaining a secure and stable connection, ensuring tight and reliable suspension performance.
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Loctite - Corporate Logo
T#:25772539
Part#: 5970
Ships in 1 Business Day
$ 55.23 USD
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This Loctite 5970 Sealant is recommended by BMW to be used to seal the rear differential cover and numerous engine oil pans. Also used for multiple MINI, Audi, and VW applications.
Lemforder - Corporate Logo
T#:398994
Part#: 33173449082
Back Ordered
$ 27.99 USD
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Bushings tends to wear over time and split or even break free from the internal sleeve, causing excessive movement and sloppy control feel. OEM Lemförder bushings are the perfect option to restore suspension back to day 1 quality.

OEM Lemförder is an engineering company that focuses on high-quality, precision manufacturing of critical suspension and steering components. Providing exceptionally high quality parts directly to BMW, as well as 50+ other big name automotive companies, such as Mercedes and Audi, their history of reliability and variety of offered parts makes them one of the biggest names for a go-to OEM parts provider. Lemförder parts place an important emphasis on design, production, and assembly, ensuring maximum reliability. They even coat all parts possible with corrosion protection for extended longevity.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform!

This item fits the following BMW Chassis:
E83 X3,E85,E86,E89 Z4

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Team MFactory - Corporate Logo
T#:379403
Part#: MF-TRS-05E39
Back Ordered
$ 999.99 USD
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$ 999.99 USD
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Allows for traction at all times by providing the most power to the wheel with more grip. Unlike plate differentials (1,1.5,2-way) helical LSDs can supply different spin rates to each axle, like when cornering.
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OEM Febi Rear Differential Carrier Bushing - Rear Positiom - E82/88 E...
Rear Position
We Price Match - Give Us A Call or Chat!
Febi - Corporate Logo
T#:382585
Part#: 33176770866
Back Ordered
$ 47.99

This product was last offered at the strikethrough price on
08-12-2026

$ 34.99 USD
Free Shipping on orders $49 and up
$ 34.99 USD
Free Shipping on orders $49 and up