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

Clear BMW chassis

Please ensure your correct model is selected

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.

Sub-Categories

Sort By:

Turner Titanium Magnetic Differential Drain Plug - M22x1.5
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
Turner Motorsport - Corporate Logo
T#:593924
Part#: 027030TMS01
In Stock
Sale - Save 25% $ 89.99

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

$ 67.49 USD
Free Shipping on orders $49 and up
Sale - Save 25%
$ 89.99

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

$ 67.49 USD
Free Shipping on orders $49 and up
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 ...
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
Turner Motorsport - Corporate Logo
T#:2955
Part#: TDR9080321
In Stock
Sale - Save 46% $ 304.99

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

$ 163.21 USD
Free Shipping
Sale - Save 46%
$ 304.99

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

$ 163.21 USD
Free Shipping
An aggressive mount design for increased cornering feel, and improved suspension performance.
Upgraded Billet Differential Cover - E82 1M, E90 E92 E93 M3
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
Turner Motorsport - Corporate Logo
T#:32350852
Part#: 049395LA
Ships in 3 Business Days
Sale - Save 3% $ 1,128.99

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

Starting at $ 1,095.12 USD
Free Shipping
Sale - Save 3%
$ 1,128.99

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

Starting at $ 1,095.12 USD
Free Shipping

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

Show More Show Less

ECS Magnetic Differential Oil Drain Plug - Most BMW & Mini Models ...
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
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
Free Shipping on orders $49 and up
Sale - Save 25%
$ 62.99

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

$ 47.24 USD
Free Shipping on orders $49 and up
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
Show More Show Less

Performance Polyurethane Differential Bushing Set - E9X M3
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
ECS - Corporate Logo
T#:596679
Part#: 026711ECS09
In Stock
Sale - Save 5% $ 177.99

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

$ 169.09 USD
Free Shipping
Sale - Save 5%
$ 177.99

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

$ 169.09 USD
Free Shipping
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.
Show More Show Less
Premium Differential Service Kit - E46 M3, E9X M3, E82 1 M Coupe ...
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
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
05-03-2026

$ 277.83 USD
Free Shipping
Sale - Save 8%
$ 301.99

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

$ 277.83 USD
Free Shipping
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!
Show More Show Less

Billet Diff Cover Replacement Drain Plug
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
Bremmen Parts - Corporate Logo
T#:19362530
Part#: 4835K45
In Stock
Sale - Save 15% $ 6.99

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

$ 5.93 USD
Free Shipping on orders $49 and up
Sale - Save 15%
$ 6.99

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

$ 5.93 USD
Free Shipping on orders $49 and up
Extreme-Pressure Steel Plug With Hex Drive - Fluoroelastomer Rubber Gasket, 9/16"-18 UN/UNF Thread