Inspect the brake backing plate for signs of fluid stains. Remove the brake drums, then pull back the wheel cylinder dust boot and check for signs of brake fluid seepage. If fluid leakage is found in these areas, replace the wheel cylinder.
See Figure 1
REMOVAL AND INSTALLATION
- Raise and safely support the rear of the vehicle.
- Remove the rear tire/wheel assemblies.
- Remove the brake drums.
- Remove the brake shoes.
- Install a suitable brake line clamp on the flexible brake line to seal the brake fluid in the system. If the proper tool is not available, do NOT use a pair of locking pliers to clamp the brake line shut. Instead, drain the fluid from the disconnected brake line into a suitable container, then plug the fitting to avoid contaminating the system.
- Place a suitable drain pan directly underneath the wheel cylinder. If necessary wash the residual brake fluid away with cold water.
- Using a brake line wrench, loosen the flare nut 1 / 8 - 1 / 4 turn while watching the metal brake line. If the flare nut moves freely, remove the flare nut and brake line.
If the metal line moves as the flare nut turns, the line is seized to the flare nut. To overcome this condition, remove the two wheel cylinder mounting bolts, then remove the brake bleeder and carefully pull the wheel cylinder outward until the wheel cylinder can be rotated while holding the flare nut. Install the wheel cylinder in reverse order if necessary.
- Remove the wheel cylinder mounting bolt(s), and remove the wheel cylinder.
- Installation is in reverse order of removal, making sure to remove the brake line clamp, properly torque all fasteners and bleed the brake hydraulic system.
See Figures 2, 3, 4 and 5
Wheel cylinder overhaul kits may be available, but often at little or no savings over a reconditioned wheel cylinder. It often makes sense with these components to substitute a new or reconditioned part instead of attempting an overhaul.
If no replacement is available, or you would prefer to overhaul your wheel cylinders, the following procedure may be used. When rebuilding and installing wheel cylinders, avoid getting any contaminants into the system. Always use clean, new, high quality brake fluid. If dirty or improper fluid has been used, it will be necessary to drain the entire system, flush the system with proper brake fluid, replace all rubber components, then refill and bleed the system.
- Remove the wheel cylinder from the vehicle and place on a clean workbench.
- First remove and discard the old rubber boots, then withdraw the pistons. Piston cylinders are equipped with seals and a spring assembly, all located behind the pistons in the cylinder bore.
See Figure 6
- Remove the remaining inner components, seals and spring assembly. Compressed air may be useful in removing these components. If no compressed air is available, be VERY careful not to score the wheel cylinder bore when removing parts from it. Discard all components for which replacements were supplied in the rebuild kit.
See Figures 7 and 8
- Wash the cylinder and metal parts in denatured alcohol or clean brake fluid.
See Figures 9 and 10
- Allow the parts to air dry or use compressed air. Do not use rags for cleaning, since lint will remain in the cylinder bore.
- Inspect the piston and replace it if it shows scratches.
See Figure 11
- Lubricate the cylinder bore and seals using clean brake fluid.
- Position the spring assembly.
- Install the inner seals, then the pistons.
See Figures 12, 13 and 14
- Insert the new boots into the counterbores by hand. Do not lubricate the boots.
See Figure 15
- Install the wheel cylinder.