CD brake rotors can be damaged in many ways.
Disc brake rotors are exposed to the elements and must very withstand the intense forces and temperatures generated during braking. As a determination, they are susceptible to damage.
Heat Checking
Heat from extreme braking sometimes causes areas of the rotor to become brittle and hard. This is known as heat checking.Under extreme conditions, or if the vehicle is left idle for an extended period, severe rust can damage the rotor.
Warping
Rotor warping is usually caused by improper tightening of the lug nuts, which puts uneven stresses on the rotor. In extreme cases, a rotor can be warped by the extreme heat generated during severe braking.
Cracking
The stresses generated in braking can cause rotors to crack. This is normally associated with poorly manufactured rotors or long worn out rotors.
Scoring
Sometimes, a piece of grit can become lodged in the pad, and this can wear a deep groove, or score, into the rotor. Grooves deeper than 0.06 inches are generally considered too deep, requiring rotor resurfacing or replacement.
Rust and Corrosion
Rotors are prepared from cast iron, which rusts. This is generally rubbed off the friction surface during braking.Low-quality disks made from poor quality cast iron are particularly susceptible.
