Driving with worn disc brake pads can be dangerous. You may find it harder to stop your vehicle, making collisions and other accidents more difficult to avoid. Driving with worn brake pads also can damage other parts of your braking system, such as the rotors and brake sensors, resulting in expensive repairs. But you can avoid these problems by paying attention to signs that your pads are worn.
Pulling or Vibrating
Brake pads that wear unevenly can cause changes in how your vehicle handles. If it pulls to the left or right when you step on the brakes, it likely is because the brakes on one side of the car are working better than those on the other side, slowing the wheels at different rates. You may also notice a vibrating or pulsating sensation when you depress the brake pedal. This is not unusual when making emergency stops in a vehicle with anti-lock brakes. But if it happens during slow, steady stops, it may indicate a warped rotor. This also can damage the brake pads.
Squealing, Scraping or Grinding Sounds
Brake pads are manufactured with metal indicators in them. When the pads are worn to the point where they should be replaced, the indicator rubs against the rotor, causing a high-pitched scraping sound. If you continue to drive the car in this condition, the scraping sound will eventually change to a grinding sound. This comes from the disc and caliper grinding against each other because there is no more brake pad between them. Have new pads installed immediately or you risk damaging the rotors as well.
Many newer-model cars come with electronic sensors installed on the brakes. When the pads are sufficiently worn, the sensors detect the shrinking distance between the caliper and rotor. This causes a light to turn on in the dashboard display. If you continue to drive after the indicator light comes on, the pads may wear so thin that the sensors scrape against the rotor, too. This can result in needing to replace the sensors as well as the pads.