Frequently Asked Questions


What is brake pedal pulsation?

Brake pedal pulsation is most often the result of thickness variation in the brake disc. Thickness variation is the technical term for a brake disc that is not uniformly thick. New brake discs are uniformly thick, and stop the vehicle smoothly. Thickness variation can develop over time and eventually lead to brake pedal pulsation.

How does thickness variation develop?

Through lateral run out in the face of the brake disc. Lateral run out is the technical term for "wobble", and this is a measurement of how the surface of the disc wobbles from side to side as it rotates. A disc with lateral run out will not wear evenly, and distortion increases over time. As the vehicle moves down the road the brakes will brush against the pads every revolution, resulting in a thin spot on the disc. Since vehicle hubs often have lateral run out due to stacked component tolerances, a new or newly machined disc will often exhibit excessive lateral run out as it turns on the hub. Most manufacture's require disc run out to 0.005".

The Pro-cut brake lathe allows us to match every disc to the hub on which it turns. The on-board computer delivers a precise alignment between the lathe axis and the hub axis, thereby guaranteeing that the Pro-cut brake lathe will machine the disc with less than 0.002" lateral run out every time.

How does Pro-Cut work?

The pro-cut lathe works on the vehicle, by attaching itself directly to the hub

The technology includes an automatic, electronically-controlled, gyroscope system which measures run-out in the hub and corrects for this to an accuracy of better than 0.05mm

The automatic surface machining of a disc is completed in around 4 minutes. The complete process takes less than 9 minutes per disc

Why resurface discs?
Why do I get a vibration through the steering wheel?

Lateral run out because brake disc is worn unevenly