Brake Booster BMW F46 Servo Brake Master Cylinder Expansion Tank 6857914

Brake Booster BMW F46 integrated with the servo, brake master cylinder, and expansion tank is a complete solution designed for the braking system of the BMW 2 Series Gran Tourer F46. The genuine BMW part ensures the correct transfer of brake pedal pressure to system pressure, resulting in stable, predictable, and safe braking. Thanks to its factory design, the servo + master cylinder + expansion tank assembly is ready for installation as a replacement for a worn or damaged unit.

Specifications and technical data

• SKU: 6857914
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 6873430
• Substitutable numbers: 6873430, 34336873430, 6868997, 34336868997, 6866164, 34336866164, 6857914
• Category: Brake Servos

Purpose and Function in the Braking System

The presented brake servo assembly with master cylinder and expansion tank is responsible for brake force assistance and precise pressure distribution within the brake circuits. The vacuum-operated servo reduces the force required to press the pedal, while the integrated brake master cylinder distributes pressure to individual circuits, ensuring uniform caliper operation. The expansion tank allows for fluid level monitoring and stable system operation under varying operating conditions.

Original BMW Design

As a component from the Brake Boosters and Force Regulators group, this product has been specifically designed for the geometry and parameters of the BMW F46 braking system. This means:

• factory-fit for bulkhead and pedal linkage mounting,
• compatibility with factory brake line routing,
• correctly selected booster characteristics and pedal travel,
• integration with the expansion tank intended for this model.

Its genuine BMW origin helps maintain the integrity of the entire braking system, which is particularly important for vehicles equipped with advanced stability control and traction control systems.

Condition, Origin, and Benefits of Choosing a Used Part

This component is from a dismantled vehicle and is offered as a used part, allowing for a significant reduction in repair costs compared to a new OEM unit, while maintaining the factory design. For many BMW F46 owners, this represents a sensible compromise between quality and budget, especially for brake system repairs where the use of original design solutions is recommended.

To maximize the potential of a used servo with master cylinder, it is advisable to ensure proper system bleeding, use brake fluid with the manufacturer's recommended specification, and regularly check for line leaks. Additional practical tips on the operation and maintenance of used components can be found in the article How to Extend the Lifespan of Used Car Parts?.

Selection and Installation in BMW F46

The selection of this servo assembly with brake master cylinder and expansion tank should be based on its compatibility with the manufacturer's markings and the vehicle's engine and equipment version. This ensures the correct brake pedal operating characteristics and compatibility with the vehicle's electronics. Installation requires standard service procedures: removal of the old unit, connection of brake lines, vacuum hose, and proper alignment with the brake pedal.

A correctly selected and installed assembly ensures:

• stable brake system pressure under various loads,
• repeatable brake engagement point,
• comfortable pedal pressure,
• consistent operation with ABS/ESP systems.

Brake System Expansion and Modernization in BMW

If you are planning a comprehensive repair or modernization of the braking area in your BMW and require other components from the same group, such as boosters, brake force regulators, or complete assistance units, check the available parts in the BMW Brake Boosters and Force Regulators category.

Summary

Brake Booster BMW F46 with servo, brake master cylinder, and expansion tank is a genuine, complete assembly designed for the BMW F46 braking system. Choosing a used OEM part allows for the preservation of factory braking parameters while reducing service costs. This solution is particularly recommended for repairs where the combination of correct brake system operation and a reasonable operating budget is crucial.