Free Engineering Tool #236

Brake Disc Runout & DTV Calculator

Enter thickness at multiple points around the disc and runout reading. Shows DTV, lateral runout and pass/fail.

DTV CheckLateral RunoutPass/Fail

Results

Disc Thickness Variation (DTV)

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Lateral Runout

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Average Thickness

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Verdict

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DTV is the difference between maximum and minimum thickness measured at multiple points. Typical limit: 0.01–0.02 mm.

Disc Thickness Variation — the difference between the thickest and thinnest points on the braking surface.

DTV (not warping) is the primary cause. As the disc rotates, varying thickness creates pulsating brake force.

Typically 0.01–0.02 mm for passenger cars. Check manufacturer specification.

Use a micrometer at 6–8 equally spaced points around the disc, at the same radius.

Side-to-side wobble of the disc measured with a dial indicator. Limit typically 0.03–0.05 mm.