Differential Covers

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

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

Looking to upgrade your drivetrain for durability and performance? The Turner Motorsport Billet Differential Cover Kit, paired with ECS Tuning's Polyurethane Transmission and Differential Mounts, offers the ultimate solution to eliminate drivetrain flex and enhance your BMW M3’s strength. Perfect for street or track use, this kit ensures top-tier performance for your E46 M3.

Turner Motorsport Billet Differential Cover Kit with ECS Polyurethane Differential Bushings

Engineered for strength and designed to handle extreme conditions, the Turner Billet Differential Cover is built from a single piece of 6061 billet aluminum and finished with a hard-coat anodizing for durability and corrosion resistance. It’s reinforced with mounting ears that prevent common failures seen with OEM diff covers, ensuring stability even during aggressive driving.

This high-performance cover features internal cooling fins that help dissipate heat, keeping the fluid cool and prolonging the life of your differential. It also maintains continuous lubrication of the ring gear, preventing fatigue and heat buildup. The cover is compatible with stock and aftermarket bushings, and comes with upgraded -6AN drain and fill plugs for easy maintenance or for expanding to an external oil cooler. A 1/8 NPT fitting is also included, making it easy to install a temp sensor and keep an eye on fluid temperatures.

Key Features:

Reinforced mounting ears: No more broken diff cover ears. Cooling optimized: External and internal fins reduce heat buildup. Increased capacity: Holds more fluid for better performance. Oil cooler ready: -6AN ports for external cooler installation. 1/8 NPT provision: Easily add a temp sensor. Sight glass: Check fluid level without removing plugs. Compatibility:

Fits E46 M3 with large case 210/215mm differentials. Designed for stock, polyurethane, or solid differential bushings. Accommodates OEM speed sensor and wire mounts. ECS Tuning Polyurethane Transmission Mount Set

Tired of soft factory transmission mounts causing mis-shifts or excessive movement? ECS Tuning’s Polyurethane Transmission Mount Set is the solution. With a durable 70A durometer rating, these mounts offer the perfect balance between everyday comfort and track-ready stiffness. For more track-focused drivers, we also offer an 80A durometer option.

These mounts feature a mechanical interlock design, ensuring longevity even in high-torque applications. Resistant to oil, water, and heat, polyurethane lasts longer than rubber and significantly reduces drivetrain deflection, improving power delivery and driving engagement.

Key Features:

Reduces transmission movement: Minimizes mis-shifts and over-revs. Polyurethane construction: Durable, with superior wear resistance. Two options: Choose between 70A for daily driving and 80A for track use. Engaging driving experience: More connected feel between driver and drivetrain. Upgrade your E46 M3 with this robust kit, and bulletproof your drivetrain today! Perfect for enthusiasts pushing their cars to the limit on the street or track.