ASE A4 Suspension and SteeringWheels and Tires Diagnosis and RepairHard
A technician is diagnosing a vehicle with a clunking noise and excessive play when wiggling the tire at the 12 and 6 o'clock positions. The play is reduced or eliminated when the brakes are applied. Which of the following is the MOST likely cause?
- AWorn tie rod ends
- BWorn ball joints
- CWorn control arm bushings
- DLoose wheel bearing
Show answer & explanationAnswer & explanation
Correct answer: D. Loose wheel bearing
Excessive play when rocking the wheel at 12 and 6 o'clock indicates vertical play, which is usually a ball joint or wheel bearing issue. If the play is reduced or eliminated when the brakes are applied, it suggests the brake caliper is taking up the slack in a loose wheel bearing, confirming the bearing as the culprit.
Why the other options are wrong
- A. Worn tie rod ends typically cause play when rocking the wheel at 3 and 9 o'clock (horizontal play), not 12 and 6 o'clock.
- B. Worn ball joints would cause play at 12 and 6 o'clock, but applying the brakes would not typically reduce or eliminate this play, as ball joints are part of the steering knuckle's attachment to the control arm, not directly influenced by caliper pressure on the rotor in this manner.
- C. Worn control arm bushings would cause clunking and potentially some play, but the specific symptom of play reducing with brake application points away from bushings.
Wheel Bearing Play Diagnosis
Identifying a loose wheel bearing by observing wheel play and its reaction to brake application.
- Excessive play at 12 and 6 o'clock often indicates a loose wheel bearing or ball joint.
- If play reduces with brake application, it confirms a loose wheel bearing.
- Brake caliper action stabilizes the rotor and hub, masking bearing play.
Memory trick: 12-6 play, brakes make it stay? Wheel bearing's gone astray!