The MGC clutch is a Borg and Beck diaphragm-spring type, the same basic design as used on the contemporary MGB but handling the significantly higher torque output of the C-series six-cylinder engine, 170 lb/ft compared to the MGB's 110 lb/ft. The clutch is available as a complete three-piece kit comprising clutch plate, clutch cover (pressure plate), and release bearing, or as individual components for targeted replacement. The clutch plate and cover are secured to the flywheel by six screws with spring washers, located on three dowels. A clutch alignment tool, which also fits the MGB from 1965 onwards, is essential for centring the clutch plate on the flywheel before the cover is tightened, ensuring the gearbox input shaft can enter the spigot bush without difficulty during refitting.
Clutch Plate and Cover
The clutch plate (driven plate) is the friction component that transmits engine torque to the gearbox input shaft. It carries friction material on both faces and incorporates torsional damper springs in its hub that absorb the rotational impulses from the six-cylinder engine's power strokes, preventing drivetrain shunt and judder. The clutch cover (pressure plate) clamps the clutch plate against the flywheel face using a diaphragm spring. When the clutch pedal is depressed, the release bearing pushes against the diaphragm spring fingers, releasing the clamping force and allowing the clutch plate to spin freely, disengaging the engine from the gearbox. A worn clutch plate causes slipping under load, initially noticeable in higher gears during acceleration, and a failed clutch cover can cause judder, drag, or difficulty engaging gear.
MGC-Specific Release Arm and Gaiter
The clutch release arm and its gaiter are specific to the MGC and are not shared with the MGB. The difference arises from the MGC's unique front gearbox cover, which relocates the release arm pivot point to clear the C-series rear engine plate. The release arm, fitting kit (including pivot bolt, bush, plain washer, and nyloc nut), and rubber gaiter are all available individually. Two clips secure the release bearing to the release arm.
The release arm bush is a common wear item, a worn bush allows the release arm to rock on its pivot, causing inconsistent clutch engagement and difficulty finding the biting point. The gaiter prevents road dirt and moisture from entering the bell housing through the release arm aperture, a torn or missing gaiter allows contamination to reach the release bearing and clutch surfaces, significantly shortening their service life.
When to Replace the Clutch
The clutch assembly should be treated as a set, replacing the plate, cover, and release bearing together is always recommended, even if only one component appears to be faulty. The labour involved in separating the engine and gearbox to access the clutch is substantial on the MGC, and replacing only the worn component risks having to repeat the entire job shortly afterwards when another component fails. The spigot bush in the crankshaft rear face should be inspected and replaced if worn whenever the gearbox is removed. The flywheel face should be checked for scoring, hot spots, and runout, a scored flywheel can be skimmed, but a flywheel with heat cracks should be replaced.