System Runout Information

SYSTEM RUNOUT:

Excessive system runout can exist as a result of the stack up of the tolerances of a rotor and a bearing which has been manufactured at one end or the other of their respective design specifications, or if either the rotor or bearing are out of specification.
The manufacturing process controls which determine the amount of rotor or bearing runout are continuously being improved to reduce the amount of system and/or component runout. During manufacturing of the brake rotor, tolerances of the braking surfaces for flatness, thickness variation and lateral runout are held very close. Maintaining these close tolerances on the rotor's braking surface is necessary to prevent brake roughness.

A lateral runout check of the rotor must be performed to determine the extent of runout.

Lateral Runout Check:

1. Remove the wheel and tire. Invert the wheel nuts and reinstall them on the studs to the specified torque. Be sure to follow the alternating nut torquing sequence to ensure proper rotor alignment.

2. Fasten a dial indicator to the caliper so the dial indictor button contacts the rotor about 13 mm (0.500 inch) from the outer edge.

3. Zero the dial indicator.

4. Move the rotor one complete revolution and observe total indicated runout (T.I.R.). Lateral runout cannot exceed 0.08 mm (0.003-inch).

^ On front wheel drive vehicles, excessive lateral runout of the rotor can often be improved by indexing the rotor on the hub one or two bolt positions from the original position. If the lateral runout CANNOT be corrected by indexing the rotor, check the hub and bearing assembly for looseness.

NOTICE: Whenever the brake rotor has been separated from the wheel bearing flange, remove any rust or foreign material from the mating surfaces of the wheel bearing flange and rotor. Failure to do this may result in excessive lateral runout of the rotor, causing brake pedal pulsation.

5. If lateral runout exceeds that specified in Step 4, refinish the rotor to specifications, reinstall rotor, and remeasure lateral runout.