BMW Differential and Gearing Upgrades for BMW E90 M3 S65 4.0L

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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 Titanium Magnetic Differential Drain Plug - M22x1.5
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Turner Motorsport - Corporate Logo
T#:593924
Part#: 027030TMS01
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$ 89.99

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$ 67.49 USD
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When both extreme-duty protection and saving every gram matters: the Turner Magnetic Differential Drain Plug.
BMW E82 E9X Rear Differential Mounts - Solid Aluminum/Delrin Race ...
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Turner Motorsport - Corporate Logo
T#:2955
Part#: TDR9080321
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Sale - Save 46% $ 304.99

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05-03-2026

$ 163.21 USD
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$ 304.99

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An aggressive mount design for increased cornering feel, and improved suspension performance.
Upgraded Billet Differential Cover - E82 1M, E90 E92 E93 M3
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Turner Motorsport - Corporate Logo
T#:32350852
Part#: 049395LA
Ships in 3 Business Days
Sale - Save 3% $ 1,128.99

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Starting at $ 1,095.12 USD
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$ 1,128.99

This product was last offered at the strikethrough price on
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Starting at $ 1,095.12 USD
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Single piece 6061 construction, optimized cooling, provisions for temp sensor, and external cooler with removable air duct.

Built to last, made from a single piece of 6061 billet aluminum with a rugged and good-looking hard-coat anodizing the Turner diff cover can handle anything you throw at it. Not only is it an absolute masterpiece, but this billet diff cover checks all the boxes for features needed. Reinforced mounting ear for strength and stability. The mounting ear is unified with the one-piece billet cover and features added material for the highest durability possible. This diff cover is cool, literally, the entire construction was designed with optimized cooling in mind. External fins are strategically placed on the rear face, bottom, and between the mounting ears of the cover, serving as effective heat sinks for optimal heat dissipation. This ensures stable temperatures, promoting longevity for both the fluid and your differential. Additionally, the internal design ensures continuous oiling and lubrication of the ring gear, maintaining its stability and preventing fatigue by controlling heat more effectively. An internal baffle at the cover's corner helps maintain proper pressure and prevents cavitation.

All of the OEM features were retained along with the upgrades. The drain and fill plugs on the diff cover are upgraded to -6AN using the provided high-pressure fittings with replaceable o-rings. The drain and fill plugs can now be used for an external oil cooler allowing you to further expand the fluid capacity for optimized cooling and service intervals. To keep an eye on things from the driver seat is 1/8 NPT provision for temp sensors, this product from Turner has you covered at every turn.

Upgrading to our Turner Billet Differential cover gives you the strength you need to push your car to its limits without worrying about snapping a diff mount from clutch kicking or other shocks to the drivetrain. In addition to its enhanced strength, this differential cover includes numerous other upgrades and conveniences. These include improved cooling and lubrication for the ring gear, upgraded fill and drain plugs, and the option to expand an external oil cooler for extreme motorsport usage. Designed to complement both upgraded daily drivers and extensively modified track cars, it also offers a visually appealing design.

Key Benefits:

Reinforced mounting ear for strength and stability
16% Increased fluid capacity
External fins on the back side, bottom, and mounting ear on the casing for maximum cooling and consistent fluid temps
Removeable air duct to direct air across the cooling fins for even more temperature control
Optimized internal design to keep fluid consistently on the ring gear
Integrated breather to prevent cavitation by venting the appropriate amount of pressure being built up in the diff housing
-6AN ports to incorporate the use of a differential cooler - this increases capacity and lowers temps allowing for extended fluid change intervals
1/8 NPT fitting for the use of a temp sensor to monitor fluid temperature
Design:

Fits manual transmission Large Case 215mm differentials
Single piece 6061 Billet aluminum construction
T6 Black hard coat anodizing for superior corrosion resistance and aesthetics
Compatible with most differential coolers(-6AN) and temp sensors(1/8 NPT)
Designed to accommodate oversized rear sway bars
Retains OEM mounting features
Factory geometry bushing size for use with OEM and aftermarket poly bushings
Removeable air duct for easy access to sensors and drain/fill plug

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OEM Rein Magnetic Differential Oil Drain Plug - M22x1.5 - Most BMW & ...
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2X Entries For Our G87 M2 Sweepstakes! We Price Match - Give Us A Call or Chat!
Rein - Corporate Logo
T#:38890943
Part#: HWU0065
In Stock
$ 23.99 USD
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$ 23.99 USD
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As components in the differential begin to wear, metal particles become loose in the diff fluid, which can lead to excess wear. This magnetic plug pulls these particles out of suspension, helping to reduce wear over time. Replaces BMW # 33117525064
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ECS Magnetic Differential Oil Drain Plug - Most BMW & Mini Models ...
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ECS - Corporate Logo
T#:366828
Part#: 009314ECS01A
In Stock
Sale - Save 25% $ 62.99

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

$ 47.24 USD
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Sale - Save 25%
$ 62.99

This product was last offered at the strikethrough price on
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$ 47.24 USD
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You use a magnetic drain plug for your engine oil, right? Why not apply the same proactive thinking to the differential too? This is a direct replacement magnetic differential drain plug for your BMW. It will catch and retain fine and larger metal particles in your diff oil. If you're proactive in your diff oil servicing, you will catch a minor issue long before it becomes a headache. Diff drain plug includes one sealing o-ring. Direct replacement for Genuine BMW part number(s): 33117525064, 33110308370, 33110152626
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Genuine BMW Differential Axle Shaft Seal w/ Lock Ring - E46 M3, E9x M...
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Genuine BMW - Corporate Logo
T#:360862
Part#: 33107510289
In Stock
9% off MSRP $ 38.69

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

$ 35.13 USD
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9% off MSRP
$ 38.69

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

$ 35.13 USD
Free Shipping on orders $49 and up
Is your rear differential leaking from the axle seal ? Here is the sealing gasket for the output axle flange, includes locking snap ring.

Loctite 5970 Gasket/Sealing Compound - 50ml
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Loctite - Corporate Logo
T#:25772539
Part#: 5970
In Stock at Vendor
$ 55.11 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.
Powerflex Polyurethane Rear Differential Rear Position Bushing Set - ...
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Powerflex - Corporate Logo
T#:376418
Part#: PFR5-1226
In Stock
$ 52.99 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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Performance Polyurethane Differential Bushing Set - E9X M3
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ECS - Corporate Logo
T#:596679
Part#: 026711ECS09
In Stock
Sale - Save 5% $ 177.99

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$ 169.09 USD
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$ 177.99

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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Differential Input Shaft Seal - E82 E46 E9X E39 E60 Z4
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Genuine BMW - Corporate Logo
T#:7924
Part#: 33121213949
In Stock
5% off MSRP $ 70.61

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

$ 66.99 USD
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5% off MSRP
$ 70.61

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

$ 66.99 USD
Free Shipping on orders $49 and up
Replace your leaking differential input seal with this Genuine BMW part. Whenever service is performed on the differential it is a good idea to check / replace any seals. This seal measures 50mm X 80mm X 9mm. We also recommend you replace the securing plate # 33121205138 at the same time.

This item fits the following BMWs:
2011 E82 BMW 1M Coupe
2001-2006 E46 BMW M3
2008-2011 E90 BMW M3 - Sedan
2008-2013 E92 BMW M3 - Coupe
2008-2013 E93 BMW M3 - Convertible
1988 E28 BMW M5
1991-1995 E34 BMW 540i M5
1999-2003 E39 BMW M5
2006-2010 E60 BMW i M5
2011+ F10 BMW M5
1987-1989 E24 BMW M6
2006-2010 E63 BMW M6
2012+ F12 BMW M6
2013+ F06 BMW M6 Gran Coupe
1988-1994 E32 BMW 740i 740il 750il
1990-1999 E31 BMW 840i 840ci 850i 850ci 850csi
2006-2008 E85 BMW Z4 M Roadster M Coupe
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Rear Differential Carrier Bushing - Front Position - E82,E90,E92,E93 ...
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Genuine BMW - Corporate Logo
T#:13479
Part#: 33312284019
In Stock
25% off MSRP $ 100.20

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

$ 74.99 USD
Free Shipping on orders $49 and up
25% off MSRP
$ 100.20

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

$ 74.99 USD
Free Shipping on orders $49 and up
BMW M replacement bushing. Great stock replacement for M vehicles or as an upgraded to the non-M bushings.
BMW Differential Seal - Rear Axle
For pre LCI models 335i, 335is and 335xi, from production date 07/2009
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Genuine BMW - Corporate Logo
T#:31655802
Part#: 33108860346
Ships in 1-2 days
2% off MSRP $ 96.58

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

$ 94.99 USD
Free Shipping on orders $49 and up
2% off MSRP
$ 96.58

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

$ 94.99 USD
Free Shipping on orders $49 and up
Proper fluid levels in the rear differential are crucial for its performance and longevity. Ignoring a leaking shaft seal can lead to severe damage. Each vehicle requires two seals.