The MGB GT V8 clutch is hydraulically operated. Pressing the clutch pedal moves a piston in the master cylinder on the bulkhead, displacing hydraulic fluid through a steel pipe to the slave cylinder mounted on the gearbox bellhousing. The slave cylinder piston pushes the clutch fork, which releases the clutch pressure plate clamping force. Hydraulic operation provides smooth, predictable clutch action with the precise control needed for hill-starts and traffic driving.
Master Cylinder
The clutch master cylinder is mounted on the bulkhead near the brake master cylinder. It is a small hydraulic cylinder with a piston, return spring, seals, and a fluid reservoir. The V8 uses a separate clutch master cylinder reservoir throughout production, distinct from the brake master cylinder reservoir. Master cylinder seals wear in service and the cylinder bore can corrode where moisture has entered the system, causing fluid leaks and progressively softer clutch action.
Master cylinder service kits or complete replacement cylinders are available.
Slave Cylinder
The slave cylinder is mounted on the gearbox bellhousing, with its piston pushing the clutch fork. As fluid is displaced from the master cylinder, the slave cylinder piston moves outward, transferring the force to the clutch fork. Like the master cylinder, the slave cylinder has internal seals that wear and a bore that can corrode. Slave cylinder service kits and complete replacement cylinders are available.
Hydraulic Pipework
A steel pipe runs from the master cylinder along the chassis to a flexible hose that connects to the slave cylinder, allowing for engine and gearbox movement. The flexible hose is a wear item and should be inspected during any clutch work, a hose that has swelled internally can act as a non-return valve, preventing the slave cylinder from releasing properly and causing the clutch to drag.
Bleeding
After any work on the clutch hydraulics, the system must be bled to remove air from the fluid. Air in the system causes a soft, spongy clutch pedal and incomplete clutch release. Bleeding is done at the bleed nipple on the slave cylinder, with the master cylinder reservoir kept topped up throughout the procedure.
MGOC Spares
MGOC Spares supplies clutch master cylinders, slave cylinders, hydraulic pipework, flexible hoses and service kits for the MGB GT V8.