The maximum life of a disc brake rotor is achieved when it reaches what we call the minimum thickness.
Disc (Rotor) Minimum Thickness is determined by the motor vehicle manufacturer during initial vehicle design. One of the features which are considered when determining Rotor minimum thickness are:
- Heat absorption & dissipation.
- Brake systems convert kinetic energy into heat energy.
This energy is created by the driver when he puts his foot on the brake pedal. Driver foot force is boosted, then converted into hydraulic pressure which forces the piston to move inside the calliper. This piston movement forces brake pads in contact with the spinning rotor. Rubbing between brake pads and the brake rotor generates heat which is then dissipated by convection to the atmosphere.
As disc (rotor) thickness reduces, so does its ability to absorb and dissipate heat generated during braking. Once Rotor Minimum Thickness has been reached, the rotors ability to absorb and dissipate heat is reduced to such an extent that a significant reduction in braking capacity can result.