Mercedes W211 S211 Brake Servo Master Cylinder Brake Booster A0004300312

Mercedes W211 S211 Brake Master Cylinder Reservoir A0004300312 is an original brake system component from the Brake Boosters and Proportioning Valves group, designed for use in E-Class W211/S211 models. This used brake master cylinder with an integrated fluid reservoir is a solution for drivers who want to restore proper brake hydraulics operation while maintaining the factory pedal feel.

Specifications and technical data

• SKU: A0004300312-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A0004300312
• Substitutable numbers: A0004300312, A 000 430 03 12, A2114300302, A 211 430 03 02
• Category: Brake Servos

Function and Application of the Mercedes W211/S211 Brake Master Cylinder

The brake master cylinder with fluid reservoir is responsible for generating working pressure in the brake system and ensuring a stable supply of fluid to the brake circuits. In conjunction with the brake booster and proportioning valve, it ensures predictable vehicle response to pedal input, appropriate brake force distribution, and maintains proper balance between axles.

For Mercedes E-Class W211/S211 models, a correctly selected brake master cylinder is crucial for:

• maintaining stable pressure in the hydraulic system during sudden braking,
• ensuring consistent, linear brake pedal operation,
• compatibility with safety systems (ABS, ESP, brake assist),
• reducing the risk of increased braking distance due to improper hydraulic operation.

Benefits of Using an Original Mercedes Brake Master Cylinder

An original component from the Brake Boosters and Proportioning Valves group ensures compatibility with the vehicle's factory specifications, leading to cohesive operation of the entire braking system. The design of the master cylinder and fluid reservoir is optimized for the W211/S211 engine bay geometry, allowing for installation without modifications to the existing lines or mounting points.

The main advantages of using this brake master cylinder include:

• compatibility with the factory brake booster and proportioning valve,
• maintaining the original pedal travel and firmness characteristics,
• proper integration with electronic braking assistance systems,
• direct replacement for a worn component without altering the system's structure.

Characteristics of the Used Component

The offered Mercedes brake master cylinder is a used part from a dismantled vehicle, significantly reducing repair costs compared to a new OEM component while retaining the original design. This solution is particularly beneficial for comprehensive service work on older W211/S211 models where both safety and operational economy are important.

To maximize the potential of a used component, it is advisable to ensure proper installation procedures, system bleeding, and the use of brake fluid meeting the vehicle manufacturer's specifications.

Operation and Extending the Lifespan of a Used Brake Master Cylinder

The durability of the brake master cylinder is significantly influenced by regular brake fluid changes, checking for line leaks, and periodically inspecting brake pedal operation for changes in travel or firmness. Maintaining the system in good condition reduces the risk of internal corrosion and air ingress, which is especially important when using parts from dismantled vehicles.

If you want to better care for dismantled components, including brake hydraulic parts, it is worth familiarizing yourself with practical maintenance tips – you can find them in the article How to Extend the Lifespan of Used Car Parts?.

Brake System Expansion and Modernization for Mercedes

If you are planning a comprehensive repair or modernization of the braking area in your Mercedes and need other components from the same group, such as a brake booster, brake proportioning valve, or additional hydraulic parts, check the available parts in the Mercedes Brake Boosters and Proportioning Valves category.

For more extensive service work on vehicles of this brand, including premium systems, a guide on selecting and operating dismantled components may also be helpful – find more information in the material Used Parts for Mercedes – Original Parts from Dismantling.