They are located in the rear brake system, inside the brake drums. Brake wheel cylinders push the brake shoes against the brake drum, causing friction that slows down the car. Over time, wheel cylinder seals may wear out and start leaking brake fluid, reducing the brakes’ effectiveness.
Brake wheel cylinders are replaced in pairs. Both rear tires will get new cylinders.
Inspect rear wheel cylinders for leakage. Inspect rear brake shoes and hardware. Replace wheel cylinders if found faulty. Adjust rear brakes. Lube backing plate. Make sure axle seals are not leaking into brake drums. Bleed the entire brake system. Perform a brake inspection, including a test drive.
It is a good idea to get the brake wheel cylinders inspected once every year. You should get your brake system inspected immediately if the brake warning light is on.
When you depress your brake pedal, the brake wheel cylinder applies pressure to the brake shoe. This pressure pushes the brake shoe into contact with the brake drum, creating friction that allows your vehicle to slow down and stop. When the brake wheel cylinder stops working, it can no longer exert enough force onto the brake shoe, and your car will not be able to brake as effectively as it should.