BMW 1 3 4 Series F20 F21 F30 F31 F32 Brake Servo Unit Master Cylinder 4081077

Brake booster with brake master cylinder for BMW 1, 3, and 4 Series F20 F21 F30 F31 F32 is an original component of the braking system from the BMW group, designed for precise integration with the factory ABS/ESP system. This used part from disassembly ensures the preservation of factory braking characteristics, offering an attractive cost-effective alternative to new components. It's a solution for users who expect proven OEM quality and consistency with the vehicle's design.

Specifications and technical data

• SKU: rhd-4081077
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 6851097
• Substitutable numbers: 6851097, 34336851097, 3433785156934336851094, 78515696851094, 3433679653134337852160, 67965317852160, 4081077, 34336858113, 6858113
• Category: Brake Servos

Purpose and Function in the Braking System

The presented brake booster unit with brake master cylinder is a component from the brake boosters and brake force regulators category, responsible for assisting the force applied to the brake pedal and properly dosing pressure in the brake circuits. The use of a complete servo + pump assembly allows for maintaining a consistent system operating characteristic, in line with the manufacturer's intentions.

In BMW 1, 3, and 4 Series F generation vehicles (F20, F21, F30, F31, F32), a properly functioning brake booster translates to:

• stable, predictable brake pedal response across the full range of loads,
• adequate assistance during sudden emergency braking,
• proper cooperation with safety systems (ABS, traction control, stability control),
• even distribution of braking force between the vehicle's axles.

Benefits of Using an Original BMW Brake Booster

The original BMW brake booster assembly has been specifically designed for the geometry and weight of the F20, F21, F30, F31, and F32 models, ensuring:

• factory fitment to engine bay mounts and existing hydraulic lines,
• preservation of the manufacturer-intended brake pedal travel and firmness characteristics,
• consistency with the operating parameters of original brake calipers and discs,
• reduced risk of bleeding and adjustment issues within the system.

By using OEM parts, the need for modifications is minimized, which is particularly important in modern vehicles with complex electronics and pressure sensors in the braking system.

Condition of Used Part and Technical Aspects of Installation

This component is from disassembly, offering a favorable combination of price and adherence to original manufacturer specifications. A used brake booster with master cylinder is a good choice in situations where:

• there has been a brake assist failure (hard pedal, extended braking distance),
• the brake master cylinder has suffered mechanical damage or leaks,
• a comprehensive system repair is necessary after a collision or corrosion of engine bay components.

During installation, it is recommended to perform a full brake system bleeding procedure according to BMW service documentation and to check all hydraulic connections for leaks. Proper installation is crucial for the safety and stable operation of the entire system.

Why Choose a Used BMW Brake Booster?

Choosing an original, used BMW part allows for maintaining high manufacturing quality while reducing service costs. This is a particularly beneficial solution for users who:

• wish to keep their vehicle in a configuration close to factory specifications,
• avoid aftermarket parts with uncertain operating characteristics,
• plan for long-term vehicle use and value predictable braking system behavior.

To maximize the potential of a disassembled part, it is advisable to consult the guide how to extend the lifespan of used car parts, which describes practical methods for maintaining and operating aftermarket components.

Summary

The brake booster with master cylinder for BMW 1, 3, and 4 Series F generation is a technically matched component of the braking system, providing proper assistance and pressure dosing in the circuits. Its original BMW origin facilitates hassle-free installation and preserves the manufacturer-intended braking characteristics. It is a sensible choice for drivers who expect consistency with the vehicle's factory design and are looking for a cost-effective repair solution.