Inspecting and Replacing Wheel Cylinder

The wheel cylinder is mounted at the top of the backing plate between the brake shoes. It is reached by removing the brake drum as described in Removing and Installing Brake Shoes. Inspect the wheel cylinder by observing the action of the brake shoes while an assistant slowly depresses the brake pedal. Replace the cylinder if the pistons stick, or if the brake shoes do not move out the same distance at a uniform rate. Also replace the cylinder if there are signs of brake fluid leakage under the dust boot. To replace a wheel cylinder the brake line must be disconnected, and it will be necessary to bleed the brakes. See 4.2 Bleeding Brakes..

To replace the wheel cylinder, first disconnect the brake line from the cylinder behind the backing plate. Seal the brake line to prevent contamination. Unhook the upper return spring and the adjusting bar tensioning spring. Push the adjusting wedge down to spread the brake shoes apart. Remove the two bolts that hold the wheel cylinder to the backing plate, and then remove the wheel cylinder.