ASE A4 Suspension and SteeringWheel Alignment Diagnosis, Adjustment, and RepairMedium
A technician is performing a four-wheel alignment. After adjusting the rear toe and thrust angle to specification, the technician moves to the front. The alignment machine shows a front right camber of -1.2 degrees, with a specification of -0.5 degrees +/- 0.5 degrees. The vehicle has an upper control arm with shims. How should the technician adjust the front right camber?
- ARemove shims from between the upper control arm and the frame at the front pivot.
- BAdd shims between the upper control arm and the frame at the rear pivot.
- CAdd shims between the upper control arm and the frame at the front pivot.
- DRemove shims from between the upper control arm and the frame at the rear pivot.
Show answer & explanationAnswer & explanation
Correct answer: A. Remove shims from between the upper control arm and the frame at the front pivot.
Negative camber means the top of the wheel is tilted inward. The current reading is -1.2 degrees, which is excessive negative camber. To reduce negative camber (move the top of the wheel outward), shims need to be removed from the front pivot of the upper control arm. This effectively moves the top of the wheel outward.
Why the other options are wrong
- B. Adding shims at the rear pivot would increase positive caster and also increase negative camber.
- C. Adding shims at the front pivot would increase negative camber, worsening the condition.
- D. Removing shims at the rear pivot would affect caster more prominently, and also increase negative camber.
Shim Adjustment for Camber
On suspensions with shim-adjustable upper control arms, removing shims from the front pivot reduces negative camber (or increases positive camber), while adding shims increases negative camber (or reduces positive camber).
- Shims at upper control arm pivots affect camber AND caster.
- Removing shims at front pivot decreases negative camber.
- Adding shims at front pivot increases negative camber.
- Equal shim changes at both pivots primarily affect camber.
Memory trick: Shims at front, camber's sway, remove to push the top away.