How to Change a Brake Cylinder

A leaking or stuck wheel cylinder on one or both of the rear brake assemblies of your car may lead to brake failure and a serious accident. You may find a replacement part on your local auto parts store. However, installing the new cylinder requires a few important guidelines. Before you start, have the vehicle service manual for your particular year and model on hand. You will need the specific procedure to torque, adjust the axle nut for your car during reassembly and bleed the brake system.

Instructions

Remove the Wheel Cylinder

1

Park your vehicle in a level surface and use the lug wrench to loosen the wheel lug nuts on the rear wheel/hub assembly you are servicing.

2

Set the transmission to Neutral (N).

3

Lift the wheel with a floor jack and position a jack stand under the frame for support.

4

Block the front wheels using a couple of wood blocks.

5

Finish removing the rear wheel.

6

Take the grease cap off from the axle end using a screwdriver and a hammer. Then remove the cotter pin and nut lock with a pair of nose pliers.

7

Unscrew the retaining nut using an axle nut socket, ratchet and ratchet extension.

8

Grab the brake drum and pull it out far enough to dislodge the outer bearing and washer. If the drum seems stuck, loosen the brake adjuster through the hole in the back of the backing plate with a screwdriver and a brake tool to turn the star wheel. This will pull back the brake shoes from the drum.

9

Wipe clean the brake shoe assembly using brake parts cleaner and a clean, lint-free rag. Then disassemble the brake shoes. If necessary, remove the other rear wheel and drum to use that brake assembly as a reference during the reassembling process.

10

Place a drain pan under the brake assembly to catch any brake fluid spill after you disconnect the brake line.

11

Loosen the brake line from the back of the wheel cylinder using a line wrench.

12

Unbolt the wheel cylinder two mounting bolts with a wrench or ratchet and socket.

13

Finish removing the line fitting, plug the line and remove the wheel cylinder off the backing plate.

Install the Wheel Cylinder

14

Remove the side boots from the new wheel cylinder. Then take out the pistons, cups and spring from inside the cylinder. James E. Duffy, in Modern Automotive Technology, recommends coating all these parts with new brake fluid and reassemble the cylinder. This will help prime the new cylinder.

15

Place the new wheel cylinder in position and start the brake line fitting by hand to avoid stripping the threads.

16

Fasten the two cylinder mounting bolts and tighten them with the wrench or ratchet and socket.

17

Finish tightening the line fitting using the line wrench but do not over-tighten.

18

Reassemble the brake shoe assembly using the opposite brake assembly as reference if necessary.

19

Install the brake drum and the front wheel bearing and washer.

20

Tighten the axle-adjusting nut using the axle nut socket, following the procedure indicated by your car manufacturer in your vehicle service manual.

21

Install the nut lock and secure it in place with a new cotter pin. Then reinstall the grease cap.

22

Mount the rear wheel and tighten the wheel lug nuts using the lug wrench.

23

Lower the vehicle and remove the wood blocks from the front wheels.

24

Bleed the brakes system, following the procedure in your vehicle service manual.