Rear brakes play a vital role in slowing or stopping a vehicle. Although they typically account for 25% of the braking action, without them, the vehicle would lose control during the simplest stopping situations. Taking notice of the warning signs or symptoms of a bad brake wheel cylinder helps you diagnose the precise source of the braking issues, but also save you money, time and a lot of frustration. When the brake wheel cylinder loses its ability to supply brake fluid pressure to the brake shoes, the pressure inside the master cylinder is compromised. This is what causes the brake pedal to go all the way to the floor when pressed. Grinding sounds coming from the rear of the vehicle as you stop is another indication of two potential problems: the brake shoes are worn out and digging into the brake drum or the brake wheel cylinder is losing brake fluid pressure and not smoothly applying the brake shoes. The brakes are an essential safety feature on a car. When a problem occurs with the brake wheel cylinder, it should therefore be replaced by an experienced mechanic and handled immediately.