Audi RS4 B7 4.2 BNS Rear Axle Differential Diff I=37:9 MPC 0AR500043T WARRANTY

Listing details

The gearboxes are sold with a 90-day warranty! They were tested before removal and are in full working order.

Audi RS4 B7 4.2 BNS Rear Axle Differential Diff I=37:9 MPC is an original drivetrain component designed for the rear axle, engineered for the demanding V8 petrol engine and manual transmission. Thanks to its precisely selected gear ratio and construction tailored to the RS4's characteristics, this rear differential ensures stable torque transfer and predictable vehicle behavior during dynamic driving. It is the ideal solution for users who expect driving consistency with factory specifications and wish to maintain the sporty character of their Audi.

Specifications and technical data

• SKU: 0AR500043T
• Mark: Audi
• Condition: Used
• OEM Part Number: 0AR500043T
• Substitutable numbers: 0AR500043T, 0AR 500 043 T
• Location on the vehicle: Rear
• Fuel type: Petrol
• Gearbox type: Manual
• Part type: Differential & Housing Assembly
• Category: Differentials

Purpose and technical characteristics

The presented rear differential has been configured for use in a vehicle with a petrol engine and manual transmission, which is crucial for proper integration with the rest of the drivetrain. The I=37:9 gear ratio is selected to provide the right balance between acceleration, flexibility in higher gears, and stability at higher speeds, characteristic of the RS versions.

Its placement on the rear axle allows for effective torque distribution within the drivetrain and maintains proper traction, especially during hard acceleration and cornering. The differential construction from this series is designed to withstand high loads typical of high-power units, which translates into durability and consistent performance in daily use as well as in more demanding conditions.

Application in Audi RS4 B7 4.2 BNS

Audi RS4 B7 4.2 BNS Rear Axle Differential Diff I=37:9 MPC is dedicated to working in a sporty drivetrain configuration where precise power transfer and predictable rear axle behavior are essential. Properly matching the differential to the specific engine and transmission variant has a direct impact on:

• acceleration characteristics across the entire rev range,
• vehicle stability during load changes,
• the operation of traction and stability control systems,
• acoustic comfort and drivetrain smoothness.

For RS4 B7 users, maintaining consistency with the factory configuration is important, especially when replacing drivetrain components. Using a differential with the correct gear ratio allows you to maintain the original driving feel without unwanted changes in dynamics or system operation.

Benefits of using an original rear differential

Choosing a differential from this series primarily ensures compliance with factory specifications and predictable vehicle behavior after installation. The appropriately selected gear ratio and construction matched to the specific model influence:

• maintaining correct engine RPM at given speeds,
• proper cooperation with the manual transmission,
• stable transfer of high torque to the rear axle,
• reducing the risk of improper drivetrain operation resulting from the use of an incorrect gear ratio.

For sports-oriented cars like the RS4 B7, the choice of differential matters not only for performance but also for the longevity of other drivetrain components. The correct rear differential ratio helps reduce excessive stress on the transmission, half-shafts, and clutch components.

Condition, verification, and vehicle matching

The offered differential comes from the Differentials category and is a used part, which in practice means obtaining original construction quality while maintaining a favorable cost-to-functionality ratio. Before installation, standard verification of compatibility with the specific vehicle configuration (engine, transmission, model year, equipment version) and an operational condition check by a qualified service center are recommended.

If you are planning a comprehensive repair or upgrade of the drivetrain in your Audi and need other components from the same group, such as other differentials, drive axles, or final drive components, check the available parts in the Audi Differentials category.

Technical support and additional materials

For users who want to better understand the impact of gear ratios on driving characteristics, a guide describing the selection of drive axles and differentials for driving style will be useful, available in the article Dismantled drive axles and differentials – how to choose gear ratios for your driving style. There, you will find a discussion of definitions, gear ratios, compatibility, and practical examples of applications in various models.

If you are interested in a broader approach to choosing used components for popular car brands, it is also worth reading our guide to original aftermarket parts: The best used car parts – a guide to the most frequently chosen original parts. This will allow you to consciously plan further service and upgrade work on your vehicle.