BMW F46 Brake Booster Servo Master Cylinder Expansion Tank 6857914

BMW F46 Brake Booster Servo Master Cylinder Expansion Tank is a complete, used solution designed for the braking system in BMW F46 series models. The set combines the servo, master brake cylinder, and fluid reservoir into a single unit, which facilitates maintenance and replacement of the entire module. By maintaining the factory configuration, this component allows for consistent hydraulic and brake booster performance in accordance with the manufacturer's standards.

Specifications and technical data

• SKU: 6857914-1
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 6873430
• Substitutable numbers: 6873430, 34336873430, 6868997, 34336868997, 6866164, 34336866164, 6857914, 0204805854, 0 204 805 854
• Category: Brake Servos

Purpose and function in the braking system

The presented component belongs to the Brake Boosters and Proportioning Valves group, responsible for the proper conversion of pedal pressure into pressure within the braking system. The integrated servo assists the driver by reducing the required pedal pressure, while the master cylinder converts the pedal movement into hydraulic pressure in the lines. The expansion tank ensures the correct level of brake fluid, stabilizing the operation of the entire system.

A module configured in this way is particularly important for maintaining a repeatable, predictable brake response, which translates into driving comfort and safety. Using an original BMW solution reduces the risk of compatibility issues and facilitates future diagnostics.

Benefits of using an original BMW module

The original servo module with master cylinder and reservoir for the BMW F46 has been designed specifically for the body geometry, braking system characteristics, and operating parameters of this series' powertrains. As a result, it:

• ensures proper braking force distribution in line with factory specifications,
• maintains consistent operation with other braking system components,
• minimizes the risk of incorrect pedal travel or uneven brake performance,
• facilitates installation due to its fitment to original mounting points.

For users looking for a solution close to the factory standard, using such a module is a practical way to restore correct braking characteristics without the need for system modifications.

Condition, origin, and installation aspects

The item is offered as a used BMW part, which allows for an economical repair while maintaining the original design. The module includes the servo, master cylinder, and reservoir, so the replacement can be carried out as a single service operation without the need to source individual components separately.

Before installation, standard workshop procedures are recommended: checking connections for leaks, replacing the brake fluid, and thoroughly bleeding the system. Properly performed installation allows for stable braking system operation and reduces the risk of future leaks.

Selection and OEM number compatibility

The servo module with master cylinder and reservoir has been developed as a solution compatible with a specific OEM number and related interchangeable numbers, which facilitates part selection based on service documentation or manufacturer catalogs. In practice, this means the ability to verify compatibility with a specific version of the BMW F46 by comparing the part number and vehicle data.

Thanks to this, the user or workshop can consciously match the component to a specific car, reducing the risk of purchasing an incompatible part. This is particularly important in the case of braking systems, where differences in configuration may result from the engine version or equipment level.

Expanding BMW braking system service

If you are planning a comprehensive repair or upgrade of the braking zone in your BMW and need other elements from the same group, such as boosters, proportioning valves, or complete power brake modules, check out the available parts in the BMW Brake Boosters and Proportioning Valves category.

To better utilize the potential of a used brake module and other dismantled components, it is worth familiarizing yourself with practical tips regarding their operation and maintenance. Detailed advice can be found in the article How to extend the life of used car parts?, which describes, among other things, best practices for handling mechanical and hydraulic components.