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.
- Before disassembly, note that most brake cylinder components have a "side" which must be installed facing the right direction.
- First remove and discard the old rubber boots, then withdraw the pistons. Seals ("cups) and a spring assembly are located behind the pistons in the cylinder bore.
- 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.
- Wash the cylinder and metal parts in denatured alcohol or clean brake fluid.
- 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 pistons and replace them if scratched.
- Check the inside of the cylinder for pitting or scoring. Slight discoloration and stains from the brake fluid is normal.
- Light scoring can be removed with a fine crocus cloth, but if defects cannot be removed in this manner, the cylinder should be replaced. Honing the cylinder is not recommended.
- Lubricate the cylinder bore and seals using clean brake fluid.
- Position the spring assembly.
- Install the cup expanders, inner seals ("cups"), and then the pistons.
- Install the boots over the wheel cylinder ends. Do NOT lubricate the boots.
- Install the wheel cylinder.
Removal & Installation
- Raise and safely support the vehicle securely on jackstands.
- Remove the wheels.
- Remove the brake drums and shoes.
- Loosen the brake fitting with a flare nut wrench. Disconnect and cap the brake hose.
- Loosen the two wheel cylinder attaching bolts, and then remove the wheel cylinder from the support plate.
- Install the wheel cylinder and tighten the attaching bolts securely.
- Uncap and connect and the brake hose. Tighten fitting securely with a flare nut wrench.
- Install the brake drums and shoes.
- Refill and bleed the brake system.
- Install the wheels.
- Lower the vehicle.