BMW 1 3 Series E87 E90 E91 320d 120d Rear Differential Diff 2,56 Ratio WARRANTY

Listing details

The differential is sold with a 90-day warranty! It was tested before removal and is in full working order.

BMW 1 and 3 Series Rear Differential with a 2.56 ratio is an original drive axle designed for 120d and 320d models with E87, E90, and E91 body styles. This component, from the Differentials - Diffs category, ensures proper torque transfer to the rear wheels, maintaining the driving characteristics intended by BMW.

Specifications and technical data

• SKU: 7556678
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7556678
• Substitutable numbers: 33107566217, 7566217, 33107566218, 7566218, 33107556678, 7556678, 33107519931, 7519931, 33107556679, 7556679, 33107519932, 7519932
• Location on the vehicle: Rear
• Category: Differentials

Purpose and Function of the Differential

The presented rear differential for BMW 1 and 3 Series is structurally adapted for the drivetrain of 120d and 320d versions with rear-wheel drive. It is responsible for distributing torque between the rear wheels and maintaining the correct gear ratio for the entire drivetrain, which translates to predictable acceleration, stability at higher speeds, and proper functioning of the vehicle's electronic systems.

The 2.56 gear ratio is characteristic of diesel engines with higher torque, promoting smooth, economical driving while maintaining adequate dynamics. This allows the differential to support a stable drive performance for both daily use and highway driving.

Construction and Vehicle Placement

The differential belongs to the Differentials - Diffs category and is mounted at the rear of the vehicle, on the drive axle. Its rear placement allows for direct connection to the driveshaft and half-shafts, ensuring consistency with BMW's factory suspension and drivetrain system.

As an original BMW part, the differential retains factory mounting points and geometry, facilitating installation and minimizing the need for additional modifications. This makes it a beneficial solution for both workshops and individual users who expect precise fitment for the specific E87/E90/E91 platform.

Benefits of Using an Original BMW Differential

Using an original differential with the correct gear ratio in the BMW 120d and 320d offers several practical benefits:

• Maintaining Factory Driving Characteristics – the correct 2.56 ratio supports predictable vehicle behavior during acceleration and engine braking.
• Compatibility with Vehicle Electronics – proper cooperation with ABS, DSC, and traction control systems due to matching drivetrain parameters.
• Appropriate Drivetrain Load – reduced risk of excessive wear on the gearbox and half-shafts compared to random aftermarket replacements.
• Easier Diagnostics and Service – workshops familiar with the E87/E90/E91 platforms can easily identify this type of differential and its service requirements.

Condition, Origin, and Practical Application

The offered differential is a used part, sourced from disassembly, allowing for economical repair of the drivetrain while maintaining the original BMW specification. This type of solution is particularly beneficial in cases of mechanical axle failure, rear axle noise, or improper drive operation under load.

Before installation, the standard workshop procedure is recommended: checking for leaks, play, and the condition of the gear oil. A correctly selected and installed differential helps in maintaining predictable vehicle behavior in corners, during acceleration, and when loads change, which directly impacts driving safety and comfort.

Gear Ratio Selection and Additional Technical Materials

When replacing the drive axle in a BMW 1 or 3 Series, matching the gear ratio to the engine version and gearbox is crucial. If you want to better understand the relationship between the differential ratio, engine characteristics, and driving style, check out the practical guide: Used Drive Axles and Differentials – How to Choose Ratios for Your Driving Style. You will find a discussion of definitions, configuration examples, and tips for used parts from disassembly.

If you are looking for other differentials from this brand for different models, check out our category BMW Differentials - Diffs, where you will find a wide selection of drive axles tailored to specific series and engine versions.