ASE G1 Auto Maintenance and Light RepairSuspension and SteeringHard
A technician is performing a wheel alignment on a vehicle with a solid rear axle. After setting the front alignment, they find that the vehicle still pulls slightly to the left. The rear toe and camber are non-adjustable. What is the MOST likely cause of the pull?
- AInsufficient positive caster on the left front wheel
- BA worn steering gear box causing excessive play
- CExcessive negative caster on the right front wheel
- DA bent rear axle housing causing a thrust angle error
Show answer & explanationAnswer & explanation
Correct answer: D. A bent rear axle housing causing a thrust angle error
Even with a solid rear axle, if the axle housing is bent, it can cause the entire rear axle assembly to point slightly to one side, creating a thrust angle error. This will cause the vehicle to pull, even if the front alignment is correct, because the vehicle is trying to 'crab walk' down the road.
Why the other options are wrong
- A. Insufficient positive caster on the left front wheel would tend to cause a pull to the left, but the question implies the front alignment was completed, suggesting a rear issue is overriding it.
- B. A worn steering gearbox causes looseness or wandering, not a consistent pull after a front alignment has been performed.
- C. Excessive negative caster on the right front would tend to cause a pull to the right, not the left.
Thrust Angle Error
An alignment condition where the rear wheels are not parallel to the vehicle's centerline, causing the vehicle to 'crab walk'.
- Causes a pull or dog tracking (vehicle drives crookedly)
- Often due to bent rear axle, damaged control arms, or misaligned subframe
- Can be non-adjustable on many solid axle vehicles
Memory trick: If front is good, look to the rear.