ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle with a multi-link rear suspension exhibits a 'wandering' sensation at highway speeds and uneven tire wear, specifically feathering on the inner shoulder of both rear tires. The technician inspects the suspension and finds no visible play in any components. A four-wheel alignment reveals that both rear toe settings are significantly out of specification, showing excessive toe-out. Which of the following is the MOST likely cause of these symptoms?
- AA collapsed rear coil spring
- BIncorrectly adjusted rear toe links after a previous repair or impact
- CWorn rear shock absorbers
- DFailed rear wheel bearings
Show answer & explanationAnswer & explanation
Correct answer: B. Incorrectly adjusted rear toe links after a previous repair or impact
Excessive rear toe-out directly causes a wandering sensation and feathering wear on the inner shoulder of the tires. If no component play is found, an incorrect adjustment of the toe links is the most probable cause, often following a repair or minor impact.
Why the other options are wrong
- A. A collapsed coil spring would affect ride height and camber, potentially causing uneven wear, but not specifically excessive toe-out and feathering on the inner shoulder without other visible issues.
- C. Worn shock absorbers primarily affect ride quality and body control, not directly causing toe-related tire wear or wandering.
- D. Failed wheel bearings typically cause a humming or grinding noise and can lead to wheel looseness, but not the specific toe-related tire wear or wandering without significant play.
Rear Toe Adjustment
Toe refers to the inward or outward angle of the wheels when viewed from above. Rear toe significantly impacts vehicle stability and tire wear, with toe-out causing wandering and inner shoulder wear.
- Positive toe: wheels point inward (toe-in).
- Negative toe: wheels point outward (toe-out).
- Excessive toe-out causes instability and inner tire wear.
- Adjusted via eccentric bolts or adjustable links.
Memory trick: Toe-out makes tires 'WANDER' and 'FEATHER' on the inside.