ASE G1 Auto Maintenance and Light RepairSuspension and SteeringMedium
A vehicle exhibits a 'shimmy' or vibration in the steering wheel that is most noticeable at highway speeds (50-70 mph). The MOST likely cause is:
- ALow tire pressure in the rear.
- BWorn ball joints.
- CA faulty power steering pump.
- DUnbalanced front wheels.
Show answer & explanationAnswer & explanation
Correct answer: D. Unbalanced front wheels.
A shimmy or vibration felt primarily in the steering wheel at highway speeds is a classic symptom of unbalanced front wheels. The imbalance creates a rotational vibration that is transmitted through the steering linkage.
Why the other options are wrong
- A. Low tire pressure in the rear would affect ride quality and handling, but a steering wheel shimmy is usually front-end related.
- B. Worn ball joints typically cause clunking, wandering, or excessive play, not a speed-sensitive steering wheel shimmy.
- C. A faulty power steering pump would cause heavy steering effort or noise, not a vibration at speed.
Wheel Balance Symptoms
Unbalanced wheels, especially front wheels, commonly cause vibrations or shimmies that are felt in the steering wheel or throughout the vehicle at certain speed ranges.
- Requires the addition of weights to the wheel/tire assembly.
- Dynamic imbalance causes vibrations at speed.
- Can be caused by lost weights, uneven tire wear, or new tire installation.
Memory trick: Speedy shimmy? Balance the wheel, pronto!