Rotor Grooving

Excessive grooving can be caused by foreign material in contact with the rotor, but most often rotor grooving is the result of normal brake wear. DO NOT RESURFACE ROTORS FOR LIGHT GROOVING. Resurface rotors only when grooves of 1.5 mm (0.060 in.) or deeper are present.

A dime may be used to determine disc brake groove depth. Place a dime in the groove, with Roosevelt's head toward the groove. If the dime goes into the groove beyond the top of his head, the groove exceeds 1.5 mm (0.060 in.) and the rotor should be serviced. (In Canada, if any portion of the letters of "In Canada" are covered, the rotor should serviced.)

It the groove is too narrow for the dime to be inserted, it is not a cause for concern.