BMW Differential and Gearing Upgrades for BMW Z4 M Roadster S54 (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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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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$ 89.99

This product was last offered at the strikethrough price on
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When both extreme-duty protection and saving every gram matters: the Turner Magnetic Differential Drain Plug.
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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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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E46 M3, Z4M Performance Polyurethane Differential Bushing Set ...
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ECS - Corporate Logo
T#:378193
Part#: 002447ECS03KT
In Stock
Sale - Save 25% $ 197.99

This product was last offered at the strikethrough price on
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$ 148.49 USD
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$ 197.99

This product was last offered at the strikethrough price on
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$ 148.49 USD
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Worn rubber differential mounts will lead to the differential twisting and shifting around in the rear subframe. Not only will this be noisy but it's bad for driver confidence and bad for the chassis as well. Even on fresh rubber bushings the differential has deflection and twist, especially if the car has been modified for more torque. Since the differential is centrally mounted in the rear subframe, with all suspension mounts interconnected, a differential with too much deflection will affect handling and could even damage the rear subframe.

These 88A urethane E46 M3 diff mounts are much stiffer than stock but still not as solid as our Turner aluminum/Delrin bushings. This set will resist twisting much better than the stock rubber mounts. Included is the front diff mount and two rear mounts in the cover.

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BMW E46 M3 Z4 Performance Polyurethane Differential Bushing Set - Rea...
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ECS - Corporate Logo
T#:348998
Part#: 002447ECS01
In Stock
Sale - Save 25% $ 148.99

This product was last offered at the strikethrough price on
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$ 111.74 USD
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$ 148.99

This product was last offered at the strikethrough price on
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$ 111.74 USD
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Revitalize your driving experience with ECS Tuning's In-House Engineered Performance Polyurethane Differential Bushings. Say goodbye to soft factory rubber bushings and their deflection. These innovative bushings provide a substantial improvement in the connection between your right foot, the chassis, and the wheels. The outcome is a crisper power transfer from the differential to the wheels, resulting in enhanced throttle control for various driving activities. Notably, these polyurethane bushings achieve these benefits without the harshness or vibration often linked to delrin or solid differential mounts.

Manufactured using a robust 88A durometer polyurethane and a black anodized 6061-T6 aluminum sleeve, these bushings offer superior resistance to chemicals, ozone degradation, road salt, and general wear and tear. This translates to an extended service life.

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Powerflex Polyurethane Rear Differential Front Position Bushing - E46...
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Powerflex - Corporate Logo
T#:362735
Part#: PFR5-4621
In Stock
$ 42.99 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 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. 

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Powerflex BMW E46 - Z4 Rear Diff Front Mount
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Powerflex - Corporate Logo
T#:33913480
Part#: PFR5-4621H
In Stock
$ 42.99 USD
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The Powerflex Rear Diff Front Mount Bushing for the BMW E46 3 Series and Z4 is a premium upgrade designed to enhance the stability and performance of the drivetrain. Here’s an alternative description:

  • High-Performance Polyurethane: Powerflex bushings are made from advanced polyurethane, which is significantly more durable than standard rubber. This material resists wear, deformation, and the effects of heat, oil, and contaminants, making it a long-lasting solution for high-performance applications.

  • Purpose: The rear differential front mount is subjected to high levels of stress during acceleration and cornering. Over time, the stock rubber bushing can degrade, causing excessive movement in the differential. The Powerflex bushing eliminates this movement, allowing for improved drivetrain control and reducing unwanted flex.

  • Key Features:

    • Enhanced Rigidity: By replacing the softer OEM rubber with Powerflex’s stiffer polyurethane, this bushing minimizes differential movement under load, resulting in improved throttle response and sharper handling.
    • Improved Longevity: Unlike the factory rubber mounts, which can crack and wear out over time, the polyurethane construction ensures long-lasting performance and reliability.
    • Performance-Oriented Design: Powerflex’s bushing is engineered to handle the increased demands of spirited driving and track use, offering better control without sacrificing comfort.
  • Benefits:

    1. Improved Power Transfer: Reducing differential movement helps direct more power to the wheels, improving acceleration and delivering a more connected driving feel.
    2. Better Handling and Stability: With less flex in the differential, the car becomes more stable, particularly during cornering and high-speed driving, enhancing overall handling precision.
    3. Durable and Maintenance-Free: Polyurethane bushings are resistant to common automotive chemicals, heat, and road debris, providing a set-and-forget solution that lasts longer than rubber components.
  • Fitment: This bushing is designed as a direct replacement for the front mount of the rear differential in BMW E46 3 Series and Z4 models. It installs easily, without requiring modifications, and offers an immediate improvement in drivetrain response.

In summary, the Powerflex Rear Diff Front Mount Bushing is an essential upgrade for BMW E46 and Z4 drivers who want to improve drivetrain rigidity, reduce flex, and enhance overall performance. This bushing provides a durable, long-lasting solution that’s perfect for both street and track use, delivering better power transfer and handling.

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Revshift Polyurethane Differential Bushings - Street / Black (80A) - ...
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Revshift - Corporate Logo
T#:41728752
Part#: PDB-E46M-80A
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$ 109.99 USD
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Revshift polyurethane differential bushings completely replace the OEM rubber bushings on the E46 M3 and Z4M. These bushings stiffen the differential, improving the vehicle's handling capabilities and eliminating drive-line slop.
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Revshift Polyurethane Differential Bushings - Track / Green (95A) - E...
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Revshift - Corporate Logo
T#:582011
Part#: PDBE46MGREEN
In Stock
$ 109.99 USD
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$ 109.99 USD
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Revshift polyurethane differential bushings completely replace the OEM rubber bushings on the E46 M3 and Z4M. These bushings stiffen the differential, improving the vehicle's handling capabilities and eliminating drive-line slop.
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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.

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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BMW S38 Helical Limited Slip Differential
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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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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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