It is the best practice to overhaul or replace both rear wheel cylinders if either one is found to be leaking. If this is not done, the undisturbed cylinder will probable develop a leak soon after the first repair job. New wheel cylinders are available at a price low enough to make overhaul impractical, except in emergency situations.
- Disassemble the brake system as described under "Brake Shoe Replacement."
- Unbolt the wheel cylinder from the backing plate.
- Remove and discard the rubber boots, the pistons, and the cups.
- Clean all parts in brake fluid or denatured alcohol.
- If there are any pits or roughness inside the cylinder, it must be replaced. Polish off any discolored area by removing the cylinder around a piece of crocus cloth held by a finger. Do not polish the cylinder in a lengthwise direction. Clean the cylinder again after polishing. Air dry.
- Replace the piston if it is scratched or damaged in any way.
- Lubricate the cylinder bore with clean brake fluid and insert the spring and the expanders.
- Install the new cups with the flat side to the outside. Do not lubricate them.
- Install the new boot onto the piston and insert the piston into the cylinder with the flat surface towards the center of the cylinder. Do not lubricate the pistons before the installation.
- Replace the cylinder and tighten the bolts evenly.
- Reassemble the brake system and bleed the brake hydraulic system.