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Home >> Fiat >> 2017 >> 500 Lounge, Standard Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 17 (Base Brakes (Service Information) - 500 - Electric) >> Hydraulic/Mechanical >> Rotor, Brake >> Diagnosis And Testing >> Rotor RUNOUT

Rotor RUNOUT

WARNING: This page is about a different variant/trim than selected.

On-vehicle rotor runout is the combination of the individual runout of the hub face and the runout of the brake rotor (hub runout can be measured separately). To measure rotor runout on the vehicle:

  1. Raise and support the vehicle.
  2. Remove the tire and wheel assembly. Refer to REMOVAL .
  3. Install wheel mounting (lug) bolts and spacers (washers) to secure rotor onto the hub assembly. Progressively tighten the (lug) bolts to the proper specification. Refer to TORQUE SPECIFICATIONS  .
  4. Mount Dial Indicator (special tool #C-3339A, Set, Dial Indicator) with Wheel (special tool #25-W, Roller Contact Point), or equivalent, to the knuckle. Position the dial indicator wheel to contact the rotor braking surface approximately 10 mm (0.39 in.) from the outer edge of the rotor.
  5. Slowly rotate the brake rotor checking lateral runout, marking the low and high spots. Record these measurements.
  6. Check and record the runout on the opposite side of the rotor in the same fashion, marking the low and high spots.
  7. Compare runout measurement to specifications. Refer to SPECIFICATIONS  .
  8. If runout is in excess of specifications, 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.
  9. Remove the rotor from the hub. Refer to ROTOR, BRAKE, REMOVAL  .
    NOTE:

    Before measuring hub runout, clean the hub face surface with an appropriate cleaner. This provides a clean surface to get an accurate indicator reading.

  10. Mount Dial Indicator (special tool #C-3339A, Set, Dial Indicator) to the knuckle. Position the dial indicator stem so it contacts the hub face near the outer diameter. Care must be taken to position the stem outside of the stud circle, but inside of the chamfer on the hub rim.
  11. Slowly rotate the hub measuring runout. Hub runout should not exceed 0.040 mm (0.0016 inch). If runout exceeds this specification, the hub must be replaced Refer to KNUCKLE, STEERING, REMOVAL and HUB AND BEARING, REMOVAL . .
  12. If hub runout does not exceed this specification, install the original rotor back on the hub, aligning the chalk mark on the rotor with a wheel mounting stud, two studs apart from the original stud.
  13. Install wheel mounting (lug) bolts and spacers (washers) to secure rotor onto the hub assembly. Progressively tighten the (lug) bolts to specifications.
  14. Mount the Dial Indicator (special tool #C-3339A, Set, Dial Indicator) (1) and remeasure runout on both sides of the brake rotor as explained in earlier steps to see if runout is now within specifications.
  15. If runout is still not within specifications, reface or replace brake rotor. Refer to STANDARD PROCEDURE  .
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