The GMC227 stepped bore (.70"/.75") tandem brake master cylinder replaces all master cylinders used from Sept. 1978 (rectangular reservoir) until the combined servo-master was fitted in 1989. It is designed to be used with a firewall-mounted pressure regulating (proportioning) valve. Genuine AP/Caparo part, made in the UK.
IMPORTANT FITTING INSTRUCTIONS: This unit must be bench bled before installation. Prior to installing the cylinder onto the vehicle, place a block of wood underneath the pedal to prevent the pedal from traveling all the way to the floor during final bleeding. If the pedal travels to the floor it will damage the internals of the cylinder and, if equipped, upset the PWDA switch. Using Silicone brake fluid will void any warranty.
If your Mini was manufactured prior to Nov 1985, you will need a brake pipe conversion kit, either BAU5654 for right-hand or BAU5655 for left-hand. Please follow the directions with the master cylinder exactly when fitting, since the connections to the pressure regulating valve are reversed compared to original. The top outlet on the master cylinder is plumbed to the front brake circuit.