Audi A5 8T A6 C7 Brake Servo Master Fluid Reservoir Expansion Tank 4G2611021

Audi A5 8T A6 C7 Brake Servo Master Fluid Reservoir Expansion Tank is a hydraulic system component designed for use within the brake fluid reservoir in Audi vehicles. It is responsible for the controlled connection between the reservoir and the rest of the system, supporting stable operating pressure and proper supply to the brake master cylinder. Thanks to a design consistent with factory solutions, this part allows for maintaining the correct operating parameters of the braking system.

Specifications and technical data

• SKU: 4G2611021-1
• Mark: Audi
• Condition: Used
• OEM Part Number: 4G2611021
• Substitutable numbers: 4G2611021, 4G2 611 021, 4G2 611 021 C, 4G2611021C, 8K0611367A, 8K0 611 367 A
• Part type: Brake Fluid Reservoir
• Category: Reservoirs & Caps

Purpose and function in the braking system

The presented valve operates directly at the brake fluid reservoir, responsible for stable hydraulic supply and controlled flow of the working medium. In Audi A5 8T and A6 C7 vehicles, this component contributes to the brake master cylinder supply area, influencing pedal travel consistency and predictable system response during braking.

A properly functioning valve at the reservoir reduces the risk of air ingress, facilitates system bleeding after service, and supports maintaining the correct fluid level in the working chambers. This is significant both in daily operation and during more intensive vehicle use, where pressure stability is crucial for safety.

Construction and fitment for Audi

As an element from the Brake fluid reservoirs and caps group, the valve has been designed for specific structural solutions used in Audi models. This means matched connection geometry, appropriate socket diameters, and compatibility with the factory reservoir and lines. Consequently, installation proceeds in a manner similar to the factory original, without the need for system modifications.

The used original part retains the characteristic features of Audi components, such as fitment with the reservoir body, correct flow direction, and material resistance to long-term contact with brake fluid. For the user, this means the ability to restore proper system operation while maintaining the factory design concept.

Benefits of using the valve at the reservoir

Using this component in an Audi A5 8T or A6 C7 allows in practice to:

• stabilize braking system operation after fluid replacement or hydraulic repairs,
• reduce the risk of uneven brake master cylinder supply,
• maintain predictable brake pedal travel under typical road conditions,
• maintain consistency with the factory Audi braking system architecture.

For workshops and private users, this means easier diagnostics, repeatable results after service, and the possibility of continued vehicle operation without interfering with the system's design.

Selection and safety when purchasing used brake components

When selecting a valve for the reservoir, it is crucial to verify compatibility with the specific model version and braking system configuration. It is worth paying attention to the type of reservoir used, the mounting method, and the type of line connections to avoid installation issues. It is also helpful to check if the given unit has assigned interchangeable numbers, which facilitates matching within the same vehicle platform.

If you want to broaden your knowledge about purchasing used brake components and minimize the risk of incorrect selection, use the practical tips included in the article Second-hand braking system: how to safely select discs, calipers, and ABS?. This is a helpful supplement when planning a comprehensive service of the braking system in an Audi.

Expanding Audi braking system service

If you are planning a comprehensive repair or upgrade of the braking zone in your Audi and need other elements from the same group, such as reservoirs, caps, or additional connection elements, check the available parts in the Audi brake fluid reservoirs and caps category.

Such an approach allows for renewing the entire brake fluid supply section in one service stage, which promotes long-term, stable system operation and facilitates later diagnostics of potential faults.