How to Change Wheel Cylinders

Wheel cylinders operate the rear brake shoes. In reality, they are a two-sided slave cylinder where hydraulic pressure is supplied to the center of the brake cylinder, which pushes opposing pistons outward, expanding the brake shoes. When hydraulic pressure is relieved, springs attached to the brake shoes help retract the pistons back into the cylinder. It is advisable to replace both wheel cylinders is one if found to be leaking.

You will need several tools to complete this job, including:

Floor jack
Jack stands
Lug wrench
Set of line wrenches
Hammer
Brake fluid
Set of wrenches
Drain pan

Loosen, but do not remove the lug nuts on the rear wheels with the lug wrench. Raise the rear of the car and place jack stands under the rear axle. Lower the car onto the jack stands. Continue removing the lug nuts on the rear wheels, and ultimately the rear wheels themselves.

Pull the brake drums off both rear wheels. If the drums do not want to pull off easily, hit them in the center with the hammer a few times to loosen the drum - brake dust that cakes up inside the drums cause them to stick. Pull the emergency brake handle all the way up. This will spread the shoes enough to remove the rear wheel cylinders without removing the rear brake shoes.

Loosen the brake line fitting in the back of the wheel cylinder using a line wrench. Remove the two 10mm bolts that secure the wheel cylinder to the backing plate, using a wrench. Thread the brake line off the rest of the way with your fingers. Immediately install the new cylinder by threading in the brake line as far as possible by hand.

Install the two 10mm bolts and tighten them with a wrench. Tighten the brake line with the line wrench. Release the emergency brake handle. Install the brake drum and the wheel. Tighten the lug nuts with the lug wrench. Lower the car off the jack stands, using the floor jack. Check the brake master cylinder reservoir and fill as needed to bring it up to the proper level.

Slide the drain pan under one of the wheel cylinders. Open the bleeder screw on the wheel cylinder and allow the fluid to gravity bleed. When you see a steady stream of brake fluid, close the bleeder screw. Top off the brake fluid in the master cylinder again. Slide the drain pan under the other wheel cylinder. Open the bleeder screw and allow the fluid to gravity bleed until you see a steady stream of fluid. Close the bleeder screw. Top off the brake fluid. Pump the brakes several times before you attempt to drive the vehicle. If you still don't have "good pedal," bleed the brakes again.