BMW E81 E87 E90 E91 Brake Servo Master Cylinder Brake Booster Unit 6788042

BMW E81 E87 E90 E91 Brake Servo Master Cylinder Brake Booster Unit is an original brake system component from the Brake Servos and Pressure Regulators category, designed for BMW 1 and 3 Series models. This used OEM component ensures proper brake assistance, stable pedal operation, and predictable system response during daily use.

Specifications and technical data

• SKU: 6788042
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 6788042
• Substitutable numbers: 34332454368, 2454368, 34336779718, 6779718, 34336764122, 6764122, 6788042
• Category: Brake Servos

Purpose and function in the brake system

The brake servo integrated with the master cylinder is responsible for increasing the force applied to the master cylinder pistons when the pedal is pressed, which translates into more effective braking with less driver effort. In BMW E81, E87, E90, and E92 series vehicles, a correctly selected brake servo is crucial for maintaining factory pedal feel, even pressure distribution in the circuits, and vehicle stability during emergency braking. The original OEM design ensures compatibility with factory system parameters, which is particularly important for the operation of ABS and stability control systems. As a result, after replacement, you can achieve predictable, repeatable brake performance without unwanted changes in pedal travel or delayed response.

Benefits of using an original BMW brake servo

Using a used, original brake servo with a master cylinder instead of a worn-out part allows you to restore proper brake assistance without the need for modifications to the system design. The main advantages of this solution include:

• maintaining the factory brake pedal feel,
• compatibility with factory lines and mounts,
• no need for installation modifications when the part is correctly selected,
• consistency with the vehicle's safety system operating parameters. For BMW users, it is important that original brake system components are designed for specific body styles and engine units, which minimizes the risk of installation issues and subsequent operational problems.

Selection and technical compatibility

When selecting a brake servo with a master cylinder for the BMW E81, E87, E90, and E92 series, it is crucial to compare the OEM part number and available interchangeable numbers with the vehicle's specifications. The product has assigned reference numbers that facilitate verification of compatibility with a specific engine and equipment version. To ensure proper system operation, before installation, it is recommended to:

• check the part number compatibility with the vehicle documentation,
• compare the mounting type and housing shape with the removed part,
• plan to bleed the brake system after replacement. This approach reduces the risk of mismatch and allows for maintaining braking parameters close to factory specifications.

Component condition and installation recommendations

The offered item comes from the category of used BMW parts, which allows for economical repair while maintaining the original design. Before installation, a standard visual inspection, checking for connection leaks, and verifying pedal operation after bleeding the system are recommended. Professional installation at a specialized service center helps avoid leaks and ensures proper operation of the brake assistance. Replacing the servo with a master cylinder is particularly recommended in the case of a hard brake pedal, a noticeable drop in assistance, or uneven system response. Using an original component from the same design group allows you to restore predictable braking and improve overall driving safety.

Brake system expansion and additional materials

If you are planning a comprehensive repair or upgrade of the braking area in your BMW and need other elements from the same group, such as servos, pressure regulators, or related assistance modules, check out the available parts in the BMW Brake Servos and Pressure Regulators category. During major service work on the vehicle, it is also worth taking care of other systems that affect driving comfort and safety. For help with selecting used OEM components and planning a service schedule, you may find the guide article Air conditioning and heating – part selection and maintenance for year-round comfort useful, as it describes practical procedures, examples, and answers to the most frequently asked questions from drivers.