A technician is performing a road test and notices that the vehicle consistently drifts to the left, requiring constant steering correction to keep it straight. When the technician releases the steering wheel, the vehicle immediately pulls to the left. Which of the following alignment angles is MOST likely out of specification, causing this condition?
- AExcessive positive caster on the right wheel
- BInsufficient positive caster on the right wheel
- CExcessive negative camber on the right wheel
- DExcessive negative caster on the left wheel
Show answer & explanationAnswer & explanation
Correct answer: B. Insufficient positive caster on the right wheel
Caster helps a wheel return to the straight-ahead position and provides directional stability. Positive caster on the right wheel helps pull the vehicle to the right. If the right wheel has insufficient positive caster (or too much negative caster relative to the left), it will have less 'pull' to the right, allowing the vehicle to drift or pull to the left. The general rule is that a vehicle will pull to the side with the LEAST positive caster.
Why the other options are wrong
- A. Excessive positive caster on the right wheel would cause a pull to the right, not the left.
- C. Excessive negative camber on the right wheel would cause a pull to the right, as the tire tries to roll towards its larger diameter.
- D. Excessive negative caster on the left wheel would cause a pull to the left, as the left side has less positive caster effect.
Caster Pull
A vehicle pull caused by an imbalance in caster angles between the front wheels. The vehicle tends to pull towards the side with less positive caster.
- Caster provides directional stability.
- Vehicle pulls to the side with less positive caster.
- Affects steering return-ability.
Memory trick: Less positive caster on one side means that side's 'pull' is weak, so the car drifts to the other side.