BMW 1 Series E87 120i N46 Rear Differential Diff 3,38 Ratio 7539775 WARRANTY

BMW 1 Series E87 120i N46 Rear Differential Diff 3,38 Ratio with a 3.38 gear ratio is a factory drivetrain component designed for rear-axle installation. This is a solution for users who expect consistent drivetrain performance, proper acceleration characteristics, and predictable vehicle behavior in daily operation.

Specifications and technical data

• SKU: 7539775
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7539775
• Substitutable numbers: 33107539776, 7539776, 33107539775, 7539775
• Location on the vehicle: Rear
• Category: Differentials

Purpose and function in the drivetrain

The presented rear differential is a component from the Differentials group, responsible for transferring torque to the rear wheels and properly distributing power during straight-line driving and cornering. The applied 3.38 gear ratio provides a balanced compromise between acceleration dynamics and comfortable engine RPM at constant speeds.

Its location on the vehicle at the rear axle allows for direct interaction with the driveshaft and half-shafts, which translates into stable handling and predictable traction in typical road conditions.

Technical characteristics and compatibility

The differential has been designed specifically for the BMW 1 Series E87 drivetrain with the N46 engine in the 120i version, ensuring it maintains factory mounting geometry and the correct power transmission line. The properly selected final drive ratio supports:

• smooth starting and acceleration in urban conditions,
• stable engine RPM during highway driving,
• predictable rear-axle behavior in corners.

The presence of the OEM part number and interchangeable numbers in the technical specification facilitates verification of compatibility with a specific vehicle configuration, which is essential when selecting drivetrain components for a BMW.

Condition, origin, and benefits of use

The offered differential is a used component, which allows for economical repair or replacement of the subassembly while maintaining the original BMW design. For many users, this means the ability to restore proper drivetrain operation without the need to invest in a new rear axle assembly.

Using an original differential with the correct 3.38 gear ratio helps reduce the risk of improper operation of cooperating systems (such as engine management or stability control systems), as operating parameters remain close to factory specifications.

Practical installation and maintenance tips

When replacing the rear differential in a BMW 1 Series E87 120i N46, it is worth paying attention to:

• selecting the correct gear ratio relative to the vehicle's original configuration,
• the condition of cooperating components (half-shafts, driveshaft, mounts),
• proper venting and topping up of gear oil in accordance with the vehicle manufacturer's recommendations.

This approach allows for maintaining stable drivetrain operation and limiting the wear of other components related to power transmission.

Drivetrain expansion and gear ratio selection

If you want to better understand how a 3.38 gear ratio affects driving characteristics, how to select a differential for your driving style, and what the differences are between individual rear axle configurations, it is worth consulting specialist materials. A practical discussion of the topic, along with model examples and answers to frequently asked questions, can be found in the article Dismantled rear axles and differentials – how to choose gear ratios for your driving style.

Other BMW differentials and upgrade options

If you are planning a comprehensive repair or upgrade of the drivetrain area in your BMW and need other elements from the same group, such as different gear ratio variants, differentials with different characteristics, or additional axle subassemblies, check the available parts in the BMW Differentials category.

For drivers considering performance modifications using aftermarket components, an interesting addition to your knowledge might also be the guide on safe tuning with used components, available in the article Tuning with used parts – how to gain performance without spending a fortune.