Document Dv00q3XJVv16ye2Bb1QrVyxy5

MACHINING Disc Thickness Variation LESSON TWO-DEMONSTRATION 2 Item Description 1 Rotor with dies thickness variation Item 2 Good rotor Description Disc Thickness Variation (DTV) occurs when the rotor thickness is not the same all the way around the rotor. DTV can be caused by lateral runout. Lateral runout becomes DTV as the vehicle is driven down the road and the high spot on the rotor contacts the brake pad, even when the brakes are not applied. Eventually, the pad wears the high spot off, causing a thin spot to be worn into the rotor. A sticking caliper or pad movement can cause insufficient clearance between the pad and rotor, increasing the chances of DTV. When the brakes are applied, and a rotor has DTV, the thick and thin spots on the rotor cause the brake pads to move in and out. This in-and-out pad motion causes increases and decreases in brake system pressure, which the driver can feel in the brake pedal and the steering wheel. The condition gets worse as the rotor gets hot. Brake System Diagnosis and Repair September, 2005 79