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Differential and Gearing Upgrades

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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URO Differential Output Shaft Seal W/ Lock Ring - BMW E36 E46 E53 E60...

2X Entries Into Our F80 M3 Sweepstakes

T#:43750219

Part#: 33107505604

In Stock

$ 10.00 USD

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$ 10.00 USD

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Maintaining a proper amount of fluid in the rear differential is vital to the performance and longevity of the differential. If a leaking shaft seal is left untouched, the results could be catastrophic. Two seals required per vehicle.

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Genuine BMW Output Shaft Seal - 33107505604

T#:360861

Part#: 33107505604

In Stock

9% off MSRP $ 18.20

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

$ 16.50 USD

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9% off MSRP

$ 18.20

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

$ 16.50 USD

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**Will only fit E92's after a production date of 9/2007 Two seals are required per vehicle. Maintaining a proper amount of fluid in the rear differential is vital to the performance and longevity of the differential. If a leaking shaft seal is left untouched, the results could be catastrophic.

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Genuine BMW Differential Plug Gasket, 22x27 - 07119963355

T#:348476

Part#: 07119963355

In Stock

$ 3.40 USD

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$ 3.40 USD

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When servicing the rear axle and differential, it is always best to replace this sealing washer to prevent any potential leaks from forming.

Genuine BMW Rear Axle Hex Bolt With Washer - M12 1.5x80

T#:13460

Part#: 33176760337

In Stock

$ 9.99 USD

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$ 9.99 USD

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Replace your differential mounting hardware during service to eliminate problems caused by rusted or stripped hardware.

Genuine BMW Hex Nut With Plate - 07129904862

T#:28828

Part#: 07129904862

In Stock

$ 3.99 USD

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$ 3.99 USD

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Genuine BMW Hex Nut With Plate
This item fits the following BMW Chassis:
E39 M5,E60 M5,E63 M6,E46 M3,E70 X5M,E71 X6M,E85 Z4M,E53 48IS,E30,E36,E38,E39,E46,E53 X5 X5,E63,E65,E70 X5,E71 X6,E85 Z4,E86 Z4,E89 Z4,E90,E92,E93,F01,F02,F06,F10,F12,F13,F15,F16

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Genuine BMW O-ring - 33111214144

T#:25199

Part#: 33111214144

In Stock

$ 8.99 USD

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$ 8.99 USD

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Genuine BMW O-Ring - D=90Mm/3Mm
This item fits the following BMW Chassis:
E30 M3,E36 M3,E34 M5,E60 M5,E63 M6,E46 M3,E82 1M Coupe,E85 Z4M,E30,E34,E36,E38,E46,E63,E82,E85 Z4,E86 Z4,E90,E92,E93,F06,F10,F12,F13,F80 M3,F82 M4,F83

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SKF Seal - Differential Pinion Shaft (50 X 80 X 9 mm)

T#:588869

Part#: 33121213949

In Stock

$ 17.99 USD

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$ 17.99 USD

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Corteco Output Shaft Seal

T#:583459

Part#: 33107505604

In Stock

$ 14.42

This product was last offered at the strikethrough price on
07-06-2026

$ 11.99 USD

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$ 11.99 USD

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Seals the axles into the differential

Differential Service Kit

10X Entries Into Our F80 M3 Sweepstakes

T#:15744025

Part#: 331175250640-KT

In Stock

Sale - Save 5% $ 274.99

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

$ 260.74 USD

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Qty

Sale - Save 5%

$ 274.99

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

$ 260.74 USD

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Often overlooked, scheduled rear differential service is very important. Over time gear lube breaks down causing bearings and internal components fail. Regular maintenance will keep your vehicle running properly for years to come. Three bottle of Genuine BMW Limited Slip Gear Lube 1 New Genuine BMW Drain/Fill plugs 1 ECS Magnetic Differential Oil Drain Plug Drain plug O-ring

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Differential Input Shaft Seal - Priced Each

2X Entries Into Our F80 M3 Sweepstakes

T#:49335120

Part#: 33121213949

In Stock

$ 18.99

This product was last offered at the strikethrough price on
07-27-2026

$ 15.99 USD

Limited Qty Sale

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Qty

$ 18.99

This product was last offered at the strikethrough price on
07-27-2026

$ 15.99 USD

Limited Qty Sale

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Replaces cracked or hardened valve body seals

Victor Reinz Differential Cover Gasket - E31, E32, E34, E39, E46, Z4 ...

T#:362602

Part#: 33108305033

In Stock

$ 3.01 USD

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$ 3.01 USD

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Seals the rear differential cover

Victor Reinz Shaft Seal with Lock Ring - Differential Output Shaft (7...

T#:596464

Part#: 33107510289

Ships in 2 Business Days

$ 22.99

This product was last offered at the strikethrough price on
05-07-2026

$ 18.99 USD

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$ 18.99 USD

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LSD Tune For OS Giken Differential

T#:34382134

Part#: LSD-TUNE

Ships in 2 Business Days

$ 150.00 USD

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$ 150.00 USD

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Genuine BMW Differential Dust Cover

T#:174741

Part#: 33137600693

Ships in 3 Business Days

$ 16.99 USD

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Qty

$ 16.99 USD

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Genuine BMW Dustcover Plate.

Output Shaft Seal

T#:54744784

Part#: 24207588763

Ships in 1 day

$ 2.99 USD

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$ 2.99 USD

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If you notice a puddle of transmission fluid forming underneath your vehicle, the output shaft seal may have failed and is leaking. Stop the leak before it can cause internal transmission damage and replace the output shaft seal in your vehicle today. This seal is on the back of your transmission for the front to rear propeller or driveshaft.

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E46, Z4 Differential Upgrade - 3.64 Original BMW

T#:107

Part#: 33107514198

Ships in 7 Business Days

$ 2,680.99 USD

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$ 2,680.99 USD

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Price includes $100.00 core charge.

Differential Service Kit - With Service Tools

T#:1002353

Part#: E46M3DIFSER1KT

Ships on Sep 22, 2026

$ 287.99

This product was last offered at the strikethrough price on
09-03-2026

$ 272.99 USD

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$ 272.99 USD

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Shaft Seal - Differential (Axle Drive)

2X Entries Into Our F80 M3 Sweepstakes

T#:54852004

Part#: B46.610

Special Order: No Guaranteed ETA

$ 14.99 USD

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$ 14.99 USD

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This OEM-quality replacement shaft seal from Elring is the perfect fix for keeping your gear oil where it belongs.

Elring Differential Input Shaft Seal - 50x80x9mm - BMW E82 1M, E46 M3...

2X Entries Into Our F80 M3 Sweepstakes

T#:44733256

Part#: 703.190

Special Order: No Guaranteed ETA

$ 34.99 USD

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$ 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

5X Entries Into Our F80 M3 Sweepstakes
We Price Match - Give Us A Call or Chat!

T#:36032352

Part#: 33176770788

Ships in 3 Business Days

$ 15.99 USD

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$ 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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OEM Febi Rear Differential Carrier Bushing - Rear Positiom - E82/88 E...

Rear Position

We Price Match - Give Us A Call or Chat!

T#:382585

Part#: 33176770866

Ships on Oct 22, 2026

$ 47.99 USD

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$ 47.99 USD

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