It's a sound that many dread while driving --- the screeching sound that tells you that your car's brakes need to be changed soon. Getting your brakes repaired is a relatively common car maintenance job that costs between £65 and £162 per axle if you bring it into a service location. It's important to understand your car's basic functions and why brakes start squeaking over time.
Worn Brake Pads
Over time, brake pads become worn because of normal use. Brake pads are the buffers (usually composed of steel or a ceramic material) that press against your car's rotors against the wheel to stop the car. A rotor is a round, flat metal disk attached to the car's inner wheel. Each time you press down on the brake when driving your car the brake pad becomes more and more worn down. The wear indicator attached to the brake assembly gets closer to the rotor as the pad gets smaller. At a certain point in time, the brakes will start to squeal to notify you that the pads need changing.
A problem with the brake calipers may also cause the brakes to squeal. The brake caliper is the part of the brake assembly that holds the pad and the wear indicator in place. If the caliper is loose it could cause the wear indicator to drag across the rotor, causing the squealing noise. In this case, a mechanic has to either tighten or replace the loose caliper.
Another reason why brakes may squeal is a problem with the brake rotor. When the rotor is old and needs replacement, the car's brakes may make that squeaking sound when the pad presses against the bad rotor disc. Also, if the car's pads constantly press against the rotors it can cause the rotors to overheat and "glaze" over, which changes the surface of the rotor so that it can't stop the car properly. This also may cause a squeaking sound and indicate that you need a new set of rotors.