What is brake fade and a common cause?

• A. Brake fade is an unexpected brake application.
• B. Brake fade is loss of braking effectiveness due to overheating; cause: pad/rotor glaze, loss of hydraulic pressure due to overheating, or vapor in brake fluid.
• C. Brake fade is when brakes suddenly grab.
• D. Brake fade is due to tire blowout.

Answer: (B)

Brake fade happens when braking effectiveness drops because the brakes overheat. When brakes are used heavily for a sustained period, the heat can cause the friction surfaces to glaze, creating a smooth, glassy layer that reduces the grip between pads and rotors. Heat can also push the hydraulic fluid toward its boiling point; if the fluid boils, vapor forms in the lines, and vapor is compressible, so the system can’t transmit full hydraulic pressure to the brakes, leading to a soft, sinking pedal and less braking force. In extreme heat, rotor warping or further glazing can worsen the fade. These effects are common during long descents or repeated aggressive braking, which is why the described combination of glazing, fluid vapor, and pressure loss best defines brake fade.