Replacing a Rear Wheel Cylinder
One component of the hydraulic braking system’s drum brakes is the rear wheel cylinder. It has two internal pistons on each side extending from the inside of the cylinder when working the braking system. The piston will come in contact with the horns of the brake shoe and will be pushed outward to contact the inside of the diameter of the drum so that the vehicle can come to a stop. If the quality of the brakes is compromised due to a leak, you do not have to remove the brake shoe nor its hardware. But, if the cylinder is blown out and has contaminated the rear brake shoe, this is the time to replace it. Cleaning will simply not fix the problem.
Step 1 - Loosen Lug Nuts
Depending on which rear cylinder wheel you are replacing, this is where you loosen the lugs by turning it about a quarter of a turn.
Step 2 - Block the Vehicle
Use anything that can stop the car from rolling out of place while you are working on it or it can cause fatal accidents. Using a jack, place it under the car’s rear frame and lift the car. Pace jack stands for safety. You can now completely remove the lug nuts from the tires.
Step 3 – Lubricate
With penetrating lubricant, spray the brake line connection that goes to the wheel cylinder. Take a drain pan and place it under so that you can collect any leaks from the area.
Step 4 - Take off the Drum
If it is necessary, take out the rubber plug from behind the backing plate and do some readjustments to the brakes using a thin-bladed screwdriver and a brake spoon. This will make removal of the drum much easier.
Step 5 - Break Brake Fitting from Wheel Cylinder
Use a line wrench and do it carefully. The lubricant you have placed will help the brake fitting move about around the steel brake line. If this part is stuck you can easily break this part by applying more penetrating fluid but remember that if you do this, it has to be replaced. As soon as the brake fitting is free, use a wrench to remove it. The pan should still be underneath to collect any of the brake fluid.
Step 6 - Disconnect Upper Brake
Use the end of brake shoe pliers to remove from the seated retainer. Contaminated retainer should be disassembled using a brake shoe spring tool. If the brake shoes won’t be replaced, the two upper brake shoe return springs must be removed.
Step 7 - Remove Retaining Bolts
These are the parts that hold the wheel cylinder in place. Now you can remove the wheel cylinder. As soon as this part is removed simply replace it with the new replacement cylinder you have purchased. Make sure it is the same model. Simply reverse the procedure of removing it. You can now bleed it by loosening the bleed screw. As soon as the flow is steady and air has passed, you can close it.
Step 8 - Check Fluid Level
The master cylinder will tell you if you need to add more fluid due to the prior leaking. Add more if necessary to level it off, and close it well.
Step 9 - Test Brake with Assistant
Have someone push on the pedal a few times and then push down. Open the bleeder screw on the wheel cylinder until fluid is pushed out from the screw. Repeat step until the brakes feel normal both in height and firmness. Never let the master cylinder become dry, and top it off with brake fluid after you do the tests.