ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A technician is performing a pre-alignment inspection on a vehicle with a MacPherson strut front suspension. The customer reports that the vehicle feels 'nervous' or 'twitchy' at highway speeds and requires constant small steering corrections to maintain a straight path. The technician notes that the steering wheel does not consistently return to center after a turn. Which of the following alignment angles is MOST likely incorrect?
- AExcessive toe-in
- BExcessive positive camber
- CExcessive negative camber
- DInsufficient positive caster
Show answer & explanationAnswer & explanation
Correct answer: D. Insufficient positive caster
Insufficient positive caster results in reduced steering self-centering and straight-line stability. This causes the vehicle to feel 'nervous' and 'twitchy' at highway speeds, requiring constant steering input to keep it going straight, and the steering wheel will not return to center effectively after a turn.
Why the other options are wrong
- A. Excessive toe-in causes inner tire wear and can make the steering feel heavy or 'darty' at times, but is not the primary cause of poor steering returnability.
- B. Excessive positive camber causes outer tire wear and can make the steering feel heavy, but is less directly responsible for the 'nervous', 'twitchy' feel and poor returnability.
- C. Excessive negative camber causes inner tire wear and can make the steering feel more responsive, but does not typically cause a 'nervous' feel or lack of returnability.
Caster Angle (Insufficient Positive)
A condition where the steering axis is tilted too far forward or not enough rearward, reducing the self-centering action of the steering.
- Causes 'nervous' steering and poor straight-line stability.
- Reduces steering wheel returnability to center.
- Can make steering feel light or vague.
Memory trick: For a stable 'PATH', ensure enough 'CASTER' helps the wheel 'RETURN'.