How to Replace the Rear Brake Wheel Cylinder on a 2000 Astro

Replacing the rear wheel cylinders on a 2000 Chevy Astro van with drum brakes is a simple procedure. Keep in mind throughout this process that brake fluid will contaminate brake shoes. The majority of problems encountered with wheel cylinders relate to contamination, causing leaks or seizing of the pistons. Indication of significant wheel cylinder leakage is evidenced by brake fluid dripping from the brake drum. Impending leaks can be determined by lifting the wheel cylinder boots. Any fluid indicates the beginning of a leak.

Instructions

1

Block the front wheels to prevent rolling. Loosen the lug nuts on the rear wheels one turn using the lug wrench. Place the floor jack under the differential and raise the van. Place jack stands under each axle tube. Lower the van onto the stands. Continue removing the lug nuts and the wheels.

2

Pull the brake drums off the axle hub. If it resists, hit it with a hammer a couple of times between the wheel studs and close to the center. Apply the parking brake to separate the brake shoes.

3

Using a line wrench, loosen the metal brake line fitting in the rear of the wheel cylinder. To prevent leakage of the fluid, do not remove it at this point. Remove the two rear 10 mm bolts securing the wheel cylinder to the backing plate using a 10 mm socket.

4

Unpack the new wheel cylinder and remove the red cap from the rear. Remove the rear brake line using the line wrench. Immediately install the new wheel cylinder. The foremost priority is to install the brake line first. With the wheel cylinder free to move it is much easier to thread the brake line connection into the cylinder. Just thread it in as far as possible by hand only.

5

Point both pistons with the slot vertically and position the cylinder over the holes in the backing plate. Install the two bolts hand tight. Squeeze both pistons in before tightening the rear bolts. Torque the bolts to 13 foot-pounds. They are small bolts and will break easily so do not overtighten them.

6

Tighten the brake line connection in the rear of the cylinder. Release the parking brake. Make sure the brake shoe metal tab is between the vertical slot on each piston on the wheel cylinder.

7

Adjust the brakes if necessary and install the brake drum. When installed, the brake shoes must just barely touch the drum. They can be heard rubbing slightly when the drum is rotated. To adjust the brakes, turn the adjuster at the bottom between the lower part of the shoes.

8

Place the drain pan under the wheel cylinder. A helper will be needed to bleed the air out of the system. Instruct your helper that when instructed to do so, push the brake pedal to the floor and hold it there until instructed to let the pedal up. Check the brake master cylinder reservoir fluid level and correct it as necessary. Open the bleeder screw on the wheel cylinder with a line wrench. Instruct the helper to depress the pedal and hold it. Once the pedal has been depressed close the bleeder screw.
Repeat this process until the air is expelled and only brake fluid is coming from the bleeder screw.

9

Replenish the brake fluid lost in the master cylinder reservoir before moving to the opposite wheel cylinder. Repeat the same procedure to bleed the air from the wheel cylinder.

10

Refill the master cylinder reservoir with brake fluid and install the cap. Install the tires and tighten the lug nuts until they are all in contact with the wheel.

11

Use the floor jack to lower the van. Torque the wheels to 100 foot-pounds with the torque wrench. Check and fill the master cylinder reservoir as necessary and replace the cap.