BMW Differential and Gearing Upgrades for BMW 3 Series E46 (1999-2005)

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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 Motorsport - Corporate Logo
T#:593924
Part#: 027030TMS01
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When both extreme-duty protection and saving every gram matters: the Turner Magnetic Differential Drain Plug.
Turner Motorsport - Corporate Logo
T#:337
Part#: TDR4680035
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Made in the USA For our Grand-Am Cup E46 M3s we wanted a fully solid differential mount setup. The advantages of a fully-solid aluminum set is that they last forever, quickens response in the suspension, and frees up horsepower to the wheels. These fully solid aluminum diff mounts are CNC machined and lightened for a direct replacement of the original rubber pieces.

By substituting aluminum for rubber we can take out all of the deflection and 'wind up' inherent to the original rubber pieces. The high deflection rate of the stock rubber means the suspension reacts slower as the bushing is compressed. The power used to compress that bushing is instead passed straight to the axles and wheels. And since there is no time lost to deflection, response is greatly improved. These diff mounts are only recommended for racecars since the aluminum transfers more noise and vibration.

This is a 3-piece set with a single front bushing and two rear bushings to press into the cover. They mount with the stock BMW hardware.

This item fits the following BMWs:
2001-2006 E46 BMW M3
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Turner Motorsport - Corporate Logo
T#:555025
Part#: TDR4680035-01
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For our Grand-Am Cup E46 M3s we wanted a fully solid differential mount setup. The advantages of a fully-solid aluminum set is that they last forever, quickens response in the suspension, and frees up horsepower to the wheels. These fully solid aluminum diff mounts are CNC machined and lightened for a direct replacement of the original rubber pieces.

By substituting aluminum for rubber we can take out all of the deflection and 'wind up' inherent to the original rubber pieces. The high deflection rate of the stock rubber means the suspension reacts slower as the bushing is compressed. The power used to compress that bushing is instead passed straight to the axles and wheels. And since there is no time lost to deflection, response is greatly improved. These diff mounts are only recommended for racecars since the aluminum transfers more noise and vibration.

This is a 3-piece set with a single front bushing to be pressed in and two rear bushings pre-pressed into the cover. They mount with the stock BMW hardware.

This item fits the following BMWs:
2001-2006  E46 BMW  M3
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ECS - Corporate Logo
T#:366828
Part#: 009314ECS01A
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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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ECS - Corporate Logo
T#:378193
Part#: 002447ECS03KT
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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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Powerflex - Corporate Logo
T#:362735
Part#: PFR5-4621
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$ 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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ECS - Corporate Logo
T#:348998
Part#: 002447ECS01
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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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ECS - Corporate Logo
T#:378192
Part#: 002447ECS02KT
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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 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 are the two front diff mounts and the rear mount in the cover.

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ECS - Corporate Logo
T#:583896
Part#: 000920ECS01
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Ensure the longevity of your BMW's drivetrain with ECS Tuning's Magnetic Plugs. These plugs are meticulously engineered in-house to provide a perfect fit and feature a permanent magnet attached to the plug body. The magnet effectively attracts and captures tiny abrasive and ferrous metal particles, preventing their circulation through lubrication systems. Metal particles can accumulate due to various conditions such as normal wear, machining operations, casting flaws, and stress usage, leading to excessive wear of vital components. ECS Tuning's Magnetic Plugs help alleviate this concern by trapping these particles, thus safeguarding the internal components of your drivetrain. With a convenient 17mm hex head design, these plugs eliminate the need for special tools required for OEM plugs.

Key Benefits:

  • Removes abrasive metal particles from drivetrain fluid
  • Prevents excessive wear to internal components
  • Meticulously engineered for a perfect fit
  • Features a permanent magnet for efficient particle capture
  • Convenient 17mm hex head design for easy installation
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Powerflex - Corporate Logo
T#:33913480
Part#: PFR5-4621H
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$ 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.

4o


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ECS - Corporate Logo
T#:363117
Part#: 002447ECS03
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BMW E46 Z4 Rear Polyurethane Differential Bushing Performance is the ultimate upgrade for enhancing the connection between your BMW's chassis and differential. Designed by Turner Motorsport, this performance bushing replaces the soft factory rubber with durable polyurethane, offering superior control and response. By minimizing vibrations and reducing deflection, this bushing ensures a more direct and responsive driving experience, making it a must-have for any performance-oriented BMW E46 or Z4 owner.

  • Enhanced Performance: Replaces the soft factory rubber with durable polyurethane for improved driveline response.
  • Reduced Vibrations: Minimizes vibrations between the chassis and differential, providing a more connected driving experience.
  • Increased Durability: Made from high-quality polyurethane, offering long-lasting performance under demanding conditions.
  • Improved Control: Reduces deflection, ensuring a more precise and responsive handling experience.
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Revshift - Corporate Logo
T#:41728752
Part#: PDB-E46M-80A
Ships in 5 Business Days
$ 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 - Corporate Logo
T#:582011
Part#: PDBE46MGREEN
Ships in 2 Business Days
$ 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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Powerflex - Corporate Logo
T#:34080712
Part#: PFR5-4620H
In Stock
$ 147.99 USD
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The Powerflex Heritage Rear Differential Mount for the BMW E46 M3, available through outlets like Turner Motorsport, is an ideal upgrade for enthusiasts seeking to enhance the performance and durability of their car's rear differential while preserving its classic appearance. The Heritage Series is tailored for those who prefer a more subtle aesthetic than the brightly colored bushings typical of Powerflex's standard line.

Key features:

  • Heritage Polyurethane Composition: The bushings are made from high-performance polyurethane, providing superior resistance to wear, cracking, and degradation compared to the original rubber mounts. This helps improve handling without compromising ride comfort.
  • Classic Appearance: Unlike the regular Powerflex bushings, which come in bright colors (yellow or purple), the Heritage Series bushings are finished in a muted dark green/black, allowing them to blend seamlessly into the undercarriage of the vehicle, ideal for those who prefer a more OEM look.
  • Enhanced Handling and Stability: The rear diff mount works to reduce the unwanted movement of the differential, which translates to improved traction, better throttle response, and more consistent handling in high-load scenarios like hard cornering or acceleration. This significantly reduces wheel hop and enhances rear-end stability.
  • Direct Fitment: These mounts are designed to be a direct replacement for the factory bushings, requiring no additional modifications. This makes them an excellent choice for both DIY and professional installs.
  • Perfect for Street and Track Use: Combining durability and flexibility, this mount is suitable for E46 M3s that see a mix of daily driving and occasional track use, offering the best of both worlds by improving responsiveness while maintaining comfort.

Turner Motorsport often emphasizes the balance of performance and OEM-like comfort with these mounts, making them an excellent choice for those wanting to upgrade their rear differential mounting without detracting from the car's original feel.

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Powerflex - Corporate Logo
T#:378993
Part#: PFR5-4625X2
Ships in 8 Business Days
$ 94.99 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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ECS - Corporate Logo
T#:378219
Part#: 002447ECS04KT
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Your rear differential is indirectly connected to your right foot through the engine and driveline, and connected to the seat of your pants through the chassis. Soft factory rubber differential bushings absorb vibrations between chassis and differential, providing comfort and softness in both of these connections.

Enter ECS Tuning's In-House Engineered Performance Polyurethane Differential Bushings. By eliminating the deflection factory rubber bushings permit, the connection between your right foot (and your seat) to the wheels is improved. Removal of this slop allows for crisper power transfer from differential to wheels, which means better throttle control while carving a canyon road, drag racing, sliding the rear end out, or just driving to work. This is achieved without the harshness or vibration associated with delrin or solid differential mounts.

Featuring a tough 88A durometer polyurethane and Black anodized 6061-T6 aluminum Sleeve, our Performance Polyurethane Differential Bushings are more resistant to chemicals, ozone degradation, road salt, and general wear and tear than factory rubber bushings, resulting in a longer service life.

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Revshift - Corporate Logo
T#:1105905
Part#: PDB-E4695A
Special Order: No Guaranteed ETA
$ 129.99 USD
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Utilizing high-precision machining technologies and their very own Polyurethane Manufacturing Department, every Revshift product is designed, manufactured, and tested in-house at their Detroit, Michigan facility.
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Rogue Engineering - Corporate Logo
T#:54388516
Part#: RE.484.FIX
Ships in 8 Business Days
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A common failure point on the BMW E46 M3 platform occurs when the side differential mounting bolt backs out, leading to stripped threads in the differential cover.