How to Remove a Rear Wheel Cylinder on a 91 Grand Am

The 1991 Pontiac Grand Am base model came with a 2.5-liter in-line four-cylinder engine and a five speed manual transmission. The rear brakes on your Grand Am are drum brakes which require a double piston wheel cylinder to apply equal pressure to both brake shoes when the brake pedal is pressed. Over time the wheel cylinder for each drain can wear out and begin to leak or become seized preventing the proper pressure from being applied to the brake shoes. Replacing either rear wheel cylinder is a straightforward task, but will require a helper when it comes time to bleed the new wheel cylinder.

Instructions

Removal

1

Park the vehicle on a level surface and set the parking brake. Loosen the lug nuts on the rear wheel with the faulty wheel cylinder with a lug wrench. Lift the rear of the vehicle into the air with a floor jack and place jack stands under the rear suspension. Lower the rear of the vehicle until it rests securely on the jack stands.

2

Remove the lug nuts for the rear wheel. Remove the rear wheel from the vehicle and set it aside. Spray the brake line fitting going to the wheel cylinder and the two torx bolts that secure it to the brake backing plate. Remove the drum from the brake backing place and wheel hub. Tap the drum with a rubber mallet, if it is stuck to the wheel hub. Wait at least 5 minutes to allow the penetrating oil to work into the bolt threads and brake line fitting.

3

Place a drain pan under the rear brake assembly. Tap the back of the brake line fitting with the flat end of a line wrench to help break the taper seal. Loosen and remove the brake line fitting from the rear of the wheel cylinder, but do not bend the brake line back of damage may occur. Install a 3/8-inch line plug to the brake line.

4

Loosen and remove the wheel cylinder mounting bolts with a 3/8-inch drive torx socket and a ratchet. Push outward on the brake shoes and remove the wheel cylinder from the brake backing plate. Drain any remaining fluid from the wheel cylinder into the drain pan and set the cylinder aside.

5

Spray brake cleaner over the brake backing plate, brake return springs, and brake shoe hold down pins. Inspect the brake shoe lining for brake fluid contamination, if the shoes have been contaminated with brake fluid you will need to replace them before continuing.

Installation

6

Push outward on the brake shoes and position the wheel cylinder against the brake backing plate. Loosely install the wheel cylinder bolts. Remove the line plug previously installed in the brake line and thread the brake line fitting into the new wheel cylinder.

7

Tighten the wheel cylinder mounting bolts to 15 foot-pounds with a 3/8-inch drive T6 Torx socket and a breaker bar. Tighten the brake line fitting to 12 foot-pounds with a torque wrench and crowfoot attachment.

8

Lift and support the vehicle hood with the hood prop rod. Remove the brake master cylinder cap and top of the brake fluid reservoir. Loosen the bleeder valve on the new wheel cylinder and wait for two minutes. Close the bleeder valve. Install one end of 3/8-inch clear tubing to the wheel cylinder bleeder valve and direct the opposite into the drain pan.

9

Instruct a helper enter the vehicle and pump the brakes until the achieve a firm brake pedal. Instruct the helper to maintain constant pressure on the pedal and to hold to the floor when applicable.

10

Loosen the bleeder valve and allow the fluid to enter the clear tubing. Close the bleeder valve when the pedal hits the floor. Instruct the helper to pump the brake pedal until a firm pedal is achieved. Loosen the bleeder valve. Tighten the bleeder valve when fluid stops flowing. Repeat this step until there are no air bubbles in the fluid traveling from the bleeder valve.

11

Install the brake drum over the wheel hub and brake backing plate. Install the wheel to the vehicle and install the lug nuts hand tight. Lift the rear of the vehicle off the jack stands and remove the jack stands from under the vehicle. Lower the vehicle to the ground. Tighten the lug nuts to 100 foot-pounds in a criss-cross pattern with a torque wrench.

12

Top off the brake fluid reservoir with fresh Dot 3 brake fluid and install the reservoir cap. Shut the vehicle hood.