The rear brakes use a leading/trailing shoe arrangement within a 7-inch cast iron drum at each rear wheel. This basic layout remained consistent from late 948cc production right through to the end of 1500 production in 1979, although the wheel cylinder specification changed between engine types. The wheel cylinders hydraulically push the brake shoes outward against the drum when the brake pedal is pressed, and the handbrake operates mechanically on the same shoes via a lever on the backplate.
Wheel Cylinders
Two wheel cylinder specifications were used, with different bore diameters affecting the hydraulic force applied to the shoes, the correct type must be identified by chassis number and engine type. Wheel cylinder seal kits allow the internal seals to be renewed without replacing the entire cylinder. The method of securing the wheel cylinder to the backplate also changed during production: the original arrangement used a beville washer and external circlip, while later production adopted a three-toothed circlip. A specialist circlip fitting tool is available for the later type, and is strongly recommended as the circlip can be difficult to locate correctly without it.
Brake Shoes and Adjustment
Brake shoes are available in standard bonded and uprated specifications. The shoe adjustment is by wedge adjuster on the backplate, accessed from the rear using a specialist brake adjuster spanner, using an incorrect tool can round the adjuster head, making future adjustment impossible without drum removal. The shoes should be adjusted so that they are as close to the drum as possible without binding when the wheel is rotated by hand.
Backplates, Springs, and Hardware
The rear brake backplates are handed (left and right) and bolt to the axle tubes. The backplate carries the wheel cylinder, the shoe return springs, the hold-down springs and posts, the adjuster assembly, and the handbrake lever. When renewing brake shoes, the return springs, hold-down springs, and posts should be inspected and renewed if they show signs of fatigue, corrosion, or stretching, weak springs are a common cause of brake squeal, uneven shoe wear, and incomplete shoe retraction that causes the brakes to drag. The handbrake lever pivot boots on each backplate should also be checked and renewed if perished, as they protect the pivot from water and road dirt.
Brake Drums
The brake drums are secured to the axle flange by screws and locktabs. The drum should be inspected for scoring, ovality, and cracking whenever the shoes are renewed, a scored or oval drum reduces braking efficiency and causes judder that can be felt through the brake pedal. Drum covers in silver or gold finish are available as a cosmetic accessory, providing a neat appearance behind open or wire wheel spokes.
Rear Brake Hose
A single flexible brake hose connects the body-mounted rigid brake pipe to the three-way union on the rear axle, allowing for the vertical movement of the axle on its springs. The three-way union distributes fluid to both rear wheel cylinders. The hose should be inspected for cracking, bulging, or chafing against the axle, internal deterioration can cause the hose lining to act as a one-way valve, allowing fluid pressure to apply the brake but preventing it from releasing.