The brake assembly is a very important system that has to be in a well-maintained condition for good braking performance. There are two types of braking systems viz. disc brakes and drum brakes. All high-performance cars manufactured today, come with all wheel disc brakes, whereas others normally have disc brakes on the front and drum brakes at the back. On a car with drum brakes, if you feel that the brakes are not functioning as effectively as before, there can be a possibility of a problem with the brake wheel cylinders. In this situation, you might have to think about a replacement, especially if the fluid is leaking from the wheel setup.
What are Brake Wheel Cylinders?
Brake wheel cylinders are exclusively found in a drum brake assembly. A brake wheel cylinder is a small part horizontally located in the wheel setup. Hydraulic fluid is forced in the cylinder from a line at the back, creating a pressure on the caliper pistons, which in turn push the brake shoes out. The brake shoes then apply pressure on the wheel drum, which causes the wheel to reduce its rotational speed. In most cases, there is a leak in the cylinder which reduces the braking efficiency on the drums. A leaking cylinder may even spoil other parts of the brake setup.
How to Replace Brake Wheel Cylinders
Since you need to work on the wheel, you will have to lift the car up with a floor jack stand and place it up on jack stands. To ensure maximum safety and support, place wooden blocks in front of the tires. Loosen the nuts on the wheel and take out the tire, after which you also need to take out the drum.
You may have to hammer the shoulders of the drum or pull it out. After the brake cylinder and shoes setup is visible, use a brake spring tool to remove the two long return springs. The spring retainer clips are also to be taken out, by turning a removal tool counterclockwise on them. This will release the shoes, after which you can access the cylinder directly.
Now, use a line wrench to loosen the rear nut of the cylinder from where the fluid comes in. Place a pan underneath the working parts for collecting any overflowing brake fluid. Take out the cylinder by loosening the mounting screws. Plug the brake fluid line to prevent it from spilling out. Handle the line carefully so as not to bend it. Mount the new cylinder on the assembly, connect the fluid line at the back, and tighten the bolts which hold the cylinder in place. Install shoes and drum in the same way in which they were removed. You may need to think about brake shoes replacement, if the shoes seem worn out.
Once this is done, it's time for checking up on the brake fluid. Bleeders are tiny screws to allow for evacuating the fluid from the cylinder. Open the bleeder and let all fluid flow out, and then close. Don't worry it will be replaced by the master cylinder (which supplies fluid to the brake cylinders). Ask another person to pump the brake pedal up and down, as this will generate a pressure in the brake system.
Watch out of too low level of fluid in the master cylinder. If it is low replenish it. Generate pressure using the brake pedal and reopen the bleeder again and drive the pedal to the floor to its fullest. Close the bleeders while maintaining the pedal pressed to the floor. Check the master cylinder to make sure if more brake fluid is to be added to it.
Well, if you have lost some braking power and if you see any fluid flowing out from the drum brake wheel assembly, you might need to consider replacing the old brake cylinders. You may also have to bleed the brake fluid to remove any air bubbles in the pressurized brake line. Make sure the fluid level in the master cylinder is at an appropriate level to enable the brake system to be at its effectiveness.