Rotor RUNOUT

On-vehicle rotor runout is the combination of the individual runout of the hub face and the runout of the rotor. (The hub and rotor are separable). To measure rotor runout on the vehicle, first remove the tire and wheel assembly. Reinstall the wheel mounting nuts on the studs, tightening the rotor to the hub. Mount the Dial Indicator (Special Tool C-3339), with Mounting Adaptor (Special Tool SP-1910) on steering arm. The dial indicator plunger should contact braking surface of rotor approximately 1" (25.5 mm) from the outer edge of rotor. Check lateral runout on both sides of the rotor, marking the low and high spots on both. For runout limits, see BRAKE ROTOR LIMITS TABLE .

If runout is in excess of the specification, check the lateral runout of the hub face. Before removing the rotor from the hub, place a chalk mark across both the rotor and the one wheel stud closest to where the high runout measurement was taken. This way, the original mounting spot of the rotor on the hub is indexed.

Remove the rotor from the hub.

Mount Dial Indicator (Special Tool C-3339), and Mounting Adaptor (Special Tool SP-1910), to the steering knuckle. Position the dial indicator stem so it contacts the hub face near the outer diameter. Care must be taken to position stem outside of the stud circle, but inside of the chamfer on the hub rim.

Hub runout should not exceed .0019" (.05 mm). If runout exceeds specification, the hub must be replaced.

If hub runout does not exceed specification, install the rotor back on the hub, aligning the chalk marks on the rotor with a wheel mounting stud, 2 studs apart from the original stud. Tighten nuts in the proper sequence.

Recheck brake rotor runout to see if the runout is now within specifications. See BRAKE ROTOR LIMITS TABLE .

If runout is not within specifications, resurface or replace the brake rotor.