Front Disc Brake Rotor: Inspection

Install disc rotor by tightening 5 wheel nuts.
Set a dial gauge on the disc rotor. Turn the disc rotor to check runout. See Fig 1 .
CAUTION: Securely fix the disc rotor to hub.

NOTE: Make sure dial gauge is set 0.39" (10 mm) inward of rotor outer perimeter. If runout of disc rotor exceeds 0.003" (0.075 mm), check for abnormal free play at hub bearing and runout in the thrust direction. See steps A - C . If hub bearing is okay, replace disc rotor.
1. Inspect rattle of bearing, give tires a shake with grasping both upper and lower sides of the tire. Also inspect to rotate the wheel smoothly.
2. Inspect the lean of axis direction using a dial gauge. Replace hub bearing if the load range exceeds 0.002" (0.05 mm).
  CAUTION: If bearing is faulty, replace it as a bearing set. Be sure to replace oil seal at every overhaul.
3. Inspect removed parts for wear and damage. If defective, replace with NEW ones.
Measure disc rotor thickness. See Figure . See TORQUE SPECIFICATIONS . If thickness of disc rotor is below 0.003" (0.075 mm), replace disc rotor.

Fig 1: Measuring Front Disc Rotor Runout

Courtesy of SUBARU OF AMERICA, INC.