Most late model cars have warning tabs on their disc brake pads. These metal tabs indicate that the brake pad is almost worn down to the metal back plate by making contact with the rotating disc rotor. This results in a shrill, but not particularly loud, squeal or whistling sound. It’s the same principle as a finger nail running down a blackboard – uncomfortable!
When this occurs, it’s time to book in to have your brakes checked and overhauled as required.
Sometimes if no action is taken to fix the problem, the metal warning tab will break off and the noise stops, giving the false impression that the problem has gone away.
The trouble is that the next noise to be heard will be the horrible grinding sound as the brakes go metal to metal. The brake job then becomes urgent and possibly more expensive and usually at an inconvenient time.
So if you hear any sounds that make you suspicious that your brakes are not 100%, give your mechanic a call to have it checked out. It will probably save you money in the long run and at least keep you and your family safe.