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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Sale - Save 25% $ 89.99

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06-14-2026

$ 67.49 USD
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Sale - Save 25%
$ 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

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

Starting at $ 1,095.12 USD
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$ 1,128.99

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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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ECS Magnetic Differential Oil Drain Plug - Most BMW & Mini Models ...
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ECS - Corporate Logo
T#:366828
Part#: 009314ECS01A
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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
06-13-2026

$ 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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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

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

$ 169.09 USD
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Sale - Save 5%
$ 177.99

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

$ 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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Limited Slip Differential - S54 3.2L & S65 4.0L Engines
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Wavetrac - Corporate Logo
T#:363875
Part#: 30309165WKWVT
Back Ordered
$ 1,595.00 USD
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$ 1,595.00 USD
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Upgrade your BMW S54 3.2L & S65 4.0L Engines with the Turner Motorsport Wavetrac Limited Slip Differential. Featuring patented Wavetrac® design, this innovative differential automatically enhances grip in low traction conditions, providing superior performance compared to traditional designs. Crafted with high-strength 9310 steel gears and ARP® fasteners, this differential ensures durability and reliability. Maintenance-free and backed by a limited lifetime warranty, the Wavetrac® differential offers peace of mind and exceptional performance for your BMW.

  • Patented Wavetrac® design improves grip in low traction conditions
  • High-strength 9310 steel gears ensure durability
  • Maintenance-free operation for the lifetime of the differential
  • Backed by a limited lifetime warranty for added assurance
  • Enhances performance and driving experience for BMW owners
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Race Polyurethane Differential Bushing, Rear Position - E8X, E9X ...
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
Powerflex Black Series - Corporate Logo
T#:376534
Part#: PFR5-1226B
Ships in 1 Business Day
$ 52.99 USD
Free Shipping on orders $49 and up

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 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 acceleration response, more direct shifting feel and overall improved drivetrain composure with Powerflex performance polyurethane 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. 

This part fits the following BMWs:
2008 - 2013 E82 1 Series Coupe 128i 135i 135is 1M Coupe
2006 - 2008 E90 323i 325i 325xi 328i 328xi 330i 330xi 335i 335xi
2009 - 2012 E90 323i 323i 328i 328xi 335d 335i 335i xDrive 335xi
2006 - 2009 E91 325xi 328i 328xi
2009 - 2011 E91 328i 328xi 
2007 - 2013 E92 328i 328xi 335i 335xi
2007 - 2013 E93 328i 335i

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E46 M3, E9X M3, E34 M5, E39 M5, Z4 M OS Giken Super Lock Limited Slip...
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OS Giken - Corporate Logo
T#:1387
Part#: BM237-HA
Ships in 2 Business Days
$ 1,950.00 USD
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$ 1,950.00 USD
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The M Dynamic limited slip unit on the M3 is designed to be a pure street car differential. It's simply not up to the rigors of professional or amateur racing. The OS Giken Super Lock LSD is giant step up in from a stock M3 lsd unit. It's ready for the extreme conditions of racing, offers 100% progressive locking capability, and is able to do this while operating smoothly and quietly. It's use of advanced technologies that make it perfect for both street cars AND pro race cars... and everything in between. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've been using them in our own Championship winning M3 race cars.

OS Giken incorporated revolutionary new ideas when developing the their own limited slip diff, utilizing their accumulated racing knowledge and experience and over 4 years of development. Their design uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The end result of their efforts is the OS Giken's OS Super Lock LSD which offers incredible durability and reliability on street and track driven BMWs. The use of highest quality materials, precise machining, forged gears and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). This is such a great design, in that it can be used in any situation -- whether it's for a street car, or a 100% Professional race car. Zero break-in required. Super smooth and quiet engagement, and 100% progressive locking capability. Professional installation is recommended.

This Limited Slip Differential Unit fits the following BMWs:
2001-2006 E46 M3 coupe & convertible
2008-2013 E9X M3 coupe & convertible
1991-1995 E34 M5 sedan
1999-2003 E39 M5 sedan
2006-2008 E85 Z4M Z4 M Coupe, Z4 M Roadster
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Differential And LSD Tune
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OS Giken - Corporate Logo
T#:34382136
Part#: BM237HAKT
Ships in 2 Business Days
$ 2,100.00 USD
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Upgrade to a better performing LSD, includes tune.
IRP Aluminum Differential Bushings - E82 1 M, E9X M3
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IRP - Individual Racing Parts - Corporate Logo
T#:587016
Part#: IRPDB-9XMAL
Special Order: No Guaranteed ETA
$ 133.99 USD
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$ 133.99 USD
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These aluminum mounts are a direct replacement for the stock rubber bushings and have been lightened to remove excess weight. Using aluminum instead of rubber eliminates the "wind up" inherent in rubber mounts, and this deflection slows suspension & drivetrain response. The tradeoff is an increase in NVH. Features: Stiffens chassis/Improves stability Less wear of other components Better durability Provides better control of chassis geometry Replaces OE: 33312284019, 33312283384 Recommended for racing use only Includes: 1 rear aluminum bushing 2 front aluminum bushings
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LSD Tune For OS Giken Differential
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OS Giken - Corporate Logo
T#:34382134
Part#: LSD-TUNE
Ships in 2 Business Days
$ 150.00 USD
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$ 150.00 USD
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