Overheating is a common source of problems in all parts of your disc brake system. It makes sense: the entire purpose of a brake system is to convert kinetic energy into heat through friction.
Familiarize yourself with the various potential problems so you can troubleshoot from the road, ask the right questions when a mechanic hands you an estimate or maybe just do the work yourself.
Disc Brakes: Rotor Problems
Overheating is the most common cause of damage to the rotors. Although cross-drilled rotors help dissipate heat, they do create the potential for stress cracks to develop as a result of intense heat. More likely, overheated rotors will warp. Warped rotors make a pulsating action that can be felt through the brake pedal when engaged. The ruined rotors eventually damage other parts of the system. Here’s how to replace rotors yourself.
Disc Brakes: Brake Pad Problems
Heavy braking, such as an emergency stop from speed or continuous braking down an incline, can overheat brake pads, causing them to glaze—basically turning what should be a gritty surface into a slippery one. Glazed brakes lose much of their ability to grab the rotors, severely diminishing braking power. You should replace them ASAP.
Disc Brakes: Caliper Problems
For disc brake calipers, overheating is more often the result of the problem. A seized caliper piston commonly causes brakes to either fail to engage or fail to disengage. The former causes loss of braking in that wheel. The latter keeps the brake pads continuously engaged, causing the car to pull to one side, overheat the pads and rotors and, eventually, begin to smoke. If you notice any of these symptoms, pull over. A tow to the mechanic or, for capable DIYers, home for the repair, is your best option in this scenario.
Disc Brakes: Brake Fluid Problems
Severe overheating of rotors and pads can transfer excessive heat through the caliper piston to the brake fluid, causing it to boil. When this happens, the fluid loses its ability to compress, which drastically reduces braking efficiency. This situation is very dangerous and you should not drive your car until repairs can be made—not even to get it home.