The rear axle and limited-slip differential

The E-Type's differential is mounted in the rear suspension cage, driving the wheels through open driveshafts with universal joints at each end. Most cars left the factory with a Powr-Lok limited-slip differential, a Salisbury-type unit that uses clutch plates to limit the speed difference between the rear wheels.

What to listen for

A whine that follows road speed and changes between drive and overrun points at the crown wheel and pinion or its bearings. A clonk taking up drive suggests worn universal joints, worn splines or excess backlash. A low rumble rising with speed can be output shaft or wheel bearings. None of these is served by hoping; all of them get more expensive as they are driven.

The limited-slip unit

A Powr-Lok in good order is barely noticeable on the road, resisting wheelspin out of slow corners and tightening its behaviour smoothly. A worn or incorrectly set unit can clatter on tight turns or behave like an open differential, doing nothing at all. Rebuilding them is specialist work, and the unit's condition is worth asking about specifically, because it is invisible on an ordinary inspection.

Oil and the driveshafts

Limited-slip differentials require oil with the correct friction characteristics for their clutch plates; ordinary gear oil in a plate-type limited-slip unit can cause chatter, and the wrong additive assumption causes more problems than it solves. The driveshaft universal joints and the hub bearings live hard lives beside the exhaust and the brakes, and their grease and condition deserve the same routine attention as the front of the car.