BMW Differential and Gearing Upgrades

Designed for track drivers, drift enthusiasts, and drag racers alike, this all-in-one driveline upgrade eliminates the factory weak points and reinforces your drivetrain for high-performance abuse. Whether you're laying down 500HP, clutch-kicking through corners, or launching hard at the strip, this cover keeps your differential secure, cool, and ready for battle.

The stock E30 differential cover features a single mounting provision—fine for a stock M20, but guaranteed to fail on your boosted high-horsepower M5X build. After years of broken covers, mounting tabs, and dreams, our team of E30 enthusiasts engineered the ultimate fix.

Unlike the brittle OEM cast aluminum cover, our upgraded differential cover is CNC-machined from 6061-T6 billet aluminum, offering a 30% increase in material strength alone. More importantly, a secondary mounting ear has been integrated into the design for added support, drastically improving stability and driveline shock absorption. The secondary mount is tied into the chassis using a reinforced sheet metal bracket and a billet aluminum plate, allowing for bolt-on installation or welding for ultimate rigidity.

Another major flaw of the factory E30 differential cover is its lack of any cooling provisions, leading to overheated fluid and premature wear. Our engineers solved this issue by incorporating advanced cooling features into the design. Large external fins have been added to the cover, and are optimized using CFD (Computational Fluid Dynamics) analysis to efficiently dissipate heat, reducing overall fluid temperatures. By maintaining a more stable differential temperature, this cover ensures consistent performance and extends the lifespan of your differential fluid. A built-in air duct assists in cooling by increasing airflow around the differential, further preventing heat-related failures. Our cover features optional -6AN fittings, allowing for easy integration of an external fluid cooler if desired. Finally, a 1/8 NPT port is included with the kit to ensure compatibility with fluid temperature monitoring systems.

Precision-machined from 6061-T6 billet aluminum and finished with a black hard coat anodizing, this cover is built to withstand hard use. Despite its robust construction and superior durability, this differential cover retains factory mounting features. This means any E30 188mm differential cover bushing can be installed, allowing you to tailor our upgraded cover to your build. The cover also accommodates large rear sway bars, ensuring fitment on cars with upgraded suspension. Our proprietary removable air duct provides easy access to sensor bungs, fill plugs, and drain plugs, making differential service a breeze.

FEATURES

Unmatched Strength & Durability - Heavily reinforced mounting locations are designed to withstand extreme horsepower, torque, and shock load. Secondary Differential Mount - A built-in secondary mount, integral sheet metal bracket, and billet adapter plate make this the strongest E30 differential cover on the market. Bolt-On or Weld-On Installation - The secondary mount is designed for easy bolt-in installation or can be welded to the chassis for ultimate rigidity. Optimized Cooling - Large external fins, designed using CFD analysis, dissipate heat efficiently, reducing overall differential fluid temperatures. Integrated Breather System - An integrated breather system reduces internal cavitation by properly venting built-up pressure. Enhanced Fluid Management - Includes a 1/8 NPT sensor port for real-time fluid temperature monitoring, and optional -6AN fittings for adding an external fluid cooler. Aerodynamic Air Duct - The included aerodynamic air duct further reduces fluid temperatures, increasing fluid service life and reliability. KIT CONTENTS

Dual Mount Differential Cover Assembly Includes the cover, sheet metal mounting bracket, billet aluminum mounting plate, and aerodynamic air duct. Installation Hardware Kit Includes everything you need to install this masterpiece on your E30! Differential Gasket Choose between a Genuine BMW paper gasket or make your own gasket with Loctite 5970. Optional -6AN fittings (2) for adding an external fluid cooler. Differential Cover Bushings Choose between Powerflex, OE MOOG, and Genuine BMW, or add your own (two E30 188mm differential cover bushings required for installation). Gear Oil Choose between Liqui Moly, Redline, and Genuine BMW, or supply your own fluid for reassembly.

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

Modern BMW's are beginning to leave the performance derived handling and power delivery in the past as the demand for more comfort and features rises. The stiff suspension components designed around having the best driving experience from a luxury car has been left for the M models and replaced with soft rubber bushings and mounts. Unfortunately, this is a good move by BMW to support the masses.

The obvious approach was to offer products so the modern BMW can be upgraded into the car the enthusiast desires, superb handling, control, and a direct delivery of power to the rear wheels. When you upgrade to our Delrin subframe mounts you reconnect that power with almost zero negative feedback.

The added appeal to someone looking to take one of these machines on the race track is Delrin can be used when solid mounts are needed and aluminum is not an option with strict regulations found in??Grand-Am, BMW CCA, and other racing series.

Product features:

• Precision machined Delrin(TM) 150 bushings.
• Precision machined 6061-T6 aluminum inserts.?
• Class legal for any racing class that does not allow a solid subframe bushing.?

Performance Benefits:

• Eliminates subframe movement for more direct throttle and suspension? response.?
• Minimizes wheel hop due to subframe deflection and movement.?

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***Installation Instructions***

These GAC differential bushings/mounts fit the following BMWs:?
2014+?F22 BMW?228i 228iX M235i M235iX?
2012+?F30 BMW?320i 320iX 328i 328iX 335i 335iX - Sedan?
2014+?F34 BMW?328i 328iX 335iX - Gran Turismo?
2014+?F32 BMW?428i 428iX 435i 435iX - Coupe?
2014+?F33 BMW?428i 428iX 435i 435iX - Convertible

2014+?F36?BMW?428iX -Gran Coupe?

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

Upgrade your drivetrain performance with ECS Tuning Performance Polyurethane Differential Bushings—engineered specifically for BMW F8x/G8x models and designed to deliver superior power transfer, durability, and driving precision.

Factory rubber differential bushings are built for comfort, absorbing vibrations between the differential and chassis during everyday driving. However, they are a known wear item that degrade over time—especially under spirited or aggressive driving conditions. Many F8x/G8x owners experience premature cracking and wear, leading to excessive drivetrain movement, reduced throttle response, and unwanted wheel hop.

ECS Tuning’s in-house engineered polyurethane differential bushings provide a high-performance solution to these common issues. By significantly reducing drivetrain deflection, these upgraded bushings enhance throttle response, improve handling stability, and minimize wheel hop—resulting in a more connected and controlled driving experience.

Constructed from durable 95A durometer red polyurethane and paired with precision CNC-machined 6061-T6 aluminum sleeves, these bushings are built to withstand extreme driveline forces while maintaining street-friendly comfort. Unlike solid or delrin mounts, ECS polyurethane bushings strike the perfect balance between performance and daily drivability—delivering increased rigidity without excessive noise, vibration, or harshness (NVH).

Whether you're carving canyon roads, launching at the drag strip, or simply commuting, these performance differential bushings ensure more efficient power delivery from the differential to the wheels—giving you better throttle modulation, traction, and overall control.

Key Features & Benefits:

Performance polyurethane differential bushings for BMW F8X models
Reduces drivetrain movement and improves power transfer
Enhances throttle response and minimizes wheel hop
95A durometer polyurethane for optimal balance of performance and comfort
CNC-machined 6061-T6 aluminum inserts with Type II black anodizing for corrosion resistance
Resistant to oil, chemicals, ozone, and road salt for extended service life
Designed to handle high torque loads and extreme driving conditions
Engineered using real-world load data and worst-case operating scenarios
Maintains street-friendly NVH levels compared to solid mounts
Replace worn factory bushings with ECS Performance Polyurethane Differential Bushings and experience tighter handling, improved drivetrain response, and long-lasting reliability.

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.

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.

The main mounting bolt for the differential in the E36 is susceptible to shearing off during extreme driving conditions. This can cause internal damage to your diff, leaving you stranded at the track or on the side of the road. Active Autowerke's differential support bracket eliminates this issue forever in under an hour installation.

Previously used Active Autowerke Part Number AA-DSB-E36

This product fits the following BMWs:
1992-1999 E36 323i 325i 328i M3

The perfect upgrade for any E46, this finned differential cover increases cooling to the rear differential to prevent over heating and possible damage. This is a complete kit including fluid and drain plugs.

Includes the following

• Aluminum finned differential cover
• Drain & fill plug with sealing o-ring
• 2 Quarts of Redline 75w90

This kit includes Turner Motorsport solid aluminum differential race mounts pre installed in the differential cover for a quick install. These mounts where developed by Turner Motorsport for their Grand-Am Cup E46 M3 race cars, the advantages of solid aluminum mounts is increased suspension & drivetrain response, less drivetrain loss resulting in more wheel horsepower, and longevity - they effectively last forever. These CNC-machined mounts are a direct replacement for the stock rubber pieces, and have been lightened to remove excess weight.