The MGC propshaft is a specific assembly, not shared with the MGB, reflecting the different flange dimensions at the rear axle end and the overall length required by the MGC's drivetrain geometry. The Salisbury rear axle fitted to the MGC uses a different pinion flange from the MGB's banjo-type axle, and the propshaft is manufactured to match. Available new or as a reconditioned exchange unit on a one-for-one basis. Two yoke flanges connect the propshaft to the gearbox output flange at the front and the rear axle pinion flange at the rear.
A yoke sleeve and gaiter with two clips (large and small) protect the sliding spline joint that accommodates changes in propshaft length as the rear axle moves on its springs over bumps and undulations, this sliding joint is essential for allowing the propshaft to change length without binding.
Universal Joints
Two sealed universal joints allow angular movement at each end of the shaft, accommodating the changing angle between the gearbox output and the rear axle input as the rear suspension deflects. The universal joints are sealed-for-life units, but on a car approaching sixty years of age, the original grease will have deteriorated and the needle roller bearings within the joint caps will have worn. A worn universal joint produces a clunk on take-up when engaging gear or lifting off the throttle, and a vibration at speed that increases with road speed. Universal joints should be replaced in pairs, if one has worn, the other is the same age and will be in a similar condition.
Flange Bolts and Lock Tabs
Four gearbox flange bolts with spring washers and nyloc nuts connect the propshaft to the gearbox output flange. On overdrive models, lock tabs are used instead of spring washers, the lock tab wraps around two adjacent bolt heads, positively preventing them from loosening under the cyclic loading that the propshaft imposes. Four axle flange bolts with spring washers and nyloc nuts connect the propshaft to the rear axle pinion flange. The bolt specifications differ between the two ends and between overdrive and non-overdrive installations, when ordering flange bolts, the gearbox type must be specified.
Gaiter and Sliding Joint
The yoke sleeve gaiter should be inspected regularly for splits and deterioration. A damaged gaiter allows road dirt and water to enter the sliding spline joint, causing the splines to wear and eventually seize, a seized sliding joint places enormous strain on the universal joints and the gearbox extension housing bearing, leading to secondary failures that are far more expensive to rectify than a simple gaiter replacement.
If the gaiter is found to be damaged, the sliding joint should be cleaned, inspected for wear, regreased, and the gaiter replaced.