Positive Fade Makes Air Disc Stop

Positive Fade Makes Air Disc Stop 40% Shorter

Air disc brakes stop up to 40% faster than drum brakes--- a major reason why the federal government reduced the maximum stop distance from 355 ft down to 250 feet.

Even though pads have less surface area and higher temperatures than drum brakes they still stop quicker. So, why?

The answer is in the difference between negative and positive fade. Negative fade occurs with drum brakes when the drum heats and swells away from the arc of the brake shoe. This causes less brake contact and longer stop distance.

Air disc brakes have positive fade. This means hotter pads swell into the rotor maintaining full surface contact with increasing torque. This causes a shorter stop distance.