GMC171 AP Master Cylinder with Single Line Plastic Reservoir for Classic Mini

The GMC171 Brake Master Cylinder, a genuine AP Master cylinder with a plastic tank, is a critical component for the hydraulic system of your Classic Mini.

Recognised as the heart of the system, it plays a vital role in ensuring efficient and safe braking. A master cylinder that allows the pedal to slowly reach the floor or shows fluid leakage is a clear indication of wear and needs replacement. While brake and clutch master cylinders may appear similar, later models like this one come with plastic reservoirs, and it's important to note that they are not interchangeable due to internal differences.

This cylinder has a 0.70" bore size, and for those seeking an all-metal version, the original metal master cylinder is available as GMC171OE, or GMC172 for a larger capacity type suitable for Cooper S models.

The large mounting foot distinguishes this brake master from the clutch master, which has a smaller foot.

It's essential to use only DOT4 or DOT5.1 brake fluids with this cylinder, as it is not designed for alternative fluids like Castrol SRF for racing or any mineral fluid. Choose the GMC171 for reliable, consistent brake performance in your Classic Mini.