RP 1415 - Hydraulic Brake Rotor Durability And Diagnostic Guidelines: Slotted

This is a machining process where narrow notches, or grooves are cut into the rotor friction surface. The function of the slots is to remove the trapped gasses, given off by the resins in the brake pads, between the friction material and the rotor surface. Since the gases are compressible, removing them creates a firmer feel to the brake pedal under higher heat situations.