How to Repair an Auto Wheel Cylinder

The wheel cylinder is the component in your vehicle's drum brake system that forces the brake shoes against the friction surface of the drum. This creates the friction required to convert the kinetic energy of the moving car or light truck into heat energy and slow or stop the vehicle. Repairing this component, when it is sticking or leaking, will restore the brake system to factory performance and prevent brake system failure as well as premature brake shoe wear.

Instructions

1

Place wheel chocks behind the wheels that will not be off the ground to prevent the vehicle from moving during the repair process. Lift the wheels off the ground and support the weight of the vehicle with the jack stands. Lifting the wheels in this manner will prevent serious injury from occurring if the floor jack should fail. Remove the wheels with the lug wrench, and place the wheels and lug nuts out of the work area to prevent loss of the lug nuts.

2

Remove the drum from the brake system. Sometimes the drum will be stuck to the axle by a build-up of rust. A few sharp blows with a hammer around the face of the drum will break the drum free of the rust to allow removal. Remove the return springs, attaching the shoes to the pivot pin at the top of the backing plate, using the brake return spring tool. Slide the shoes outward, away from the wheel cylinder.

3

Disassemble the wheel cylinder by removing the dust boots on the ends of the cylinder, and pushing the pistons, cup seals and spring out of the cylinder. Clear away as much of the debris and sediment build-up inside the wheel cylinder as you can. Lubricate the inside of the cylinder with clean brake fluid and hone the wheel cylinder, with the brake cylinder hone, until a smooth, clean surface is restored. Wheel cylinders with excessive corrosion and pitting should be replaced.

4

Reassemble the wheel cylinder using the new cup seals and dust boots supplied in the wheel cylinder kit. Lubricate all of the rubber parts with a liberal coating of clean brake fluid, before assembly, to prevent damage to the new seals. Reinstall the return springs and drum.

5

Bleed the brakes according to the bleeding sequence for your specific vehicle. This sequence varies so refer to the service manual for the proper sequence.

6

Reinstall the wheel and lower the vehicle off the jack stands and back onto the ground. Retighten the lug nuts one final time and test-drive to verify proper brake function.