How to Change the Brake Wheel Cylinder on a 1991 Grand Am

The wheel cylinders on the 1991 Pontiac Grand Am control the movement of the brake shoes on the rear wheels. As you depress the brake pedal, the master cylinder distributes brake fluid throughout the brake lines. On the rear wheels, the fluid pushes the pistons out on each side of the wheel cylinder, forcing the brake shoes against the drum in order to stop the car. Like other parts of the braking system, the wheel cylinders will wear and need replacing. The average do-it-yourself mechanic can replace the wheel cylinders in the garage or driveway, avoiding the need to take the car to a repair shop.

Instructions

1

Park the car on a level surface and turn off the key. Place a set of wheel chocks in front of the front wheels.

2

Loosen the lug nuts on the wheel you are starting with using the lug wrench, but do not remove them. Raise the Grand Am using the automobile jack. Place a jack stand under the rear axle of the car and raise it as high as possible by hand. Lower the automobile jack just enough that the car is resting on the jack stand.

3

Make a mark on the wheel to match it up with the axle using a marking crayon. This will help to keep the tires balanced when you put everything back together. Remove the lug nuts from the wheel assembly and pull the tire away from the car. Make a mark on the drum to line it up properly with the axle for balancing purposes using the marking crayon.

4

Remove the brake drum from the wheel assembly. Clean any dirt and debris from around the wheel cylinder using a shop towel. The wheel cylinder is at the top of the wheel assembly.

5

Loosen the nut on the inlet tube behind the brake backing plate using a wrench. Do not pull the brake line away from the backing plate or you may damage it. It will separate from the cylinder when you pull the cylinder off. Plug the brake line with a brake line plug to prevent fluid loss.

6

Remove the bolts securing the wheel cylinder to the backing plate using a ratchet and a 6 Torx socket. Pull the wheel cylinder away from the backing plate.

7

Place the new wheel cylinder on the brake backing plate. Torque the retaining bolts on the cylinder to 15 foot-pounds using a 6 Torx socket and torque wrench.

8

Remove the brake line plug from the brake line and connect the line to the wheel cylinder. Torque the tube nut to 12 foot-pounds with a crowfoot attachment and torque wrench.

9

Remove the cover from the master brake cylinder in the engine compartment and add brake fluid as necessary to bring it to the full mark. Install the brake drum, making sure to line up the marks you made when removing it.

10

Install the wheel and tighten the lug nuts with the lug wrench. Lower the car to the ground and retighten the lug nuts using a star pattern. Repeat the process as necessary on the other wheel.

11

Attach a clear plastic hose to the bleeder valve on the wheel cylinder. Slowly open the bleeder valve using a wrench while a helper depresses the brake pedal. Allow the fluid to flow into the drain pan until there are no bubbles coming out with the fluid. Close the valve with a wrench and torque to 65 inch-pounds with an inch-pound torque wrench. When bleeding the brakes, start with the right rear wheel, then move to the left rear and repeat the process.

12

Move to the front of the car starting with the right front wheel and repeat the procedure followed in step 11, and then move to the left side of the Grand Am. Be sure to continuously add brake fluid to the master cylinder as necessary to prevent the brake lines from pulling air into the system.