What Happens When a Brake Rotor Breaks?by KevinM
Modern disc brakes are very effective and reliable. From time to time, a brake rotor can break, creating an immediate threat to motoring safety. A broken rotor must be replaced as soon as possible to protect the driver and all around him.
Most rotor breaks take the form of cracks, usually around the base of the disk where it joins the hub section. Radial cracking outward can also occur. Other occasional rotor problems include warping, heat-checking, and rotor bluing, which happens when a rotor has been subjected to high heat.
Rotor cracks are usually the result of poor manufacturing. Low-quality rotors are often poorly cast from non-homogeneous cast iron, and these defects leave weak spots that cannot withstand the forces generated during braking. A rotor that is still in service long after it has worn out will also be susceptible to cracking.
Even the slightest defect on the rotor will cause low-frequency vibrations, known as judder, during braking. Serious rotor failures can easily cause a complete wheel lock-up and loss of control of the vehicle.