ASE A4 Suspension and SteeringWheels and Tires Diagnosis and RepairEasy
A customer reports a vibration that is felt primarily in the seat and floorboard at highway speeds (above 55 mph). Which of the following is the MOST likely cause?
- AWorn front suspension components
- BExcessive front toe-in
- CImbalance in a rear wheel assembly
- DSteering rack internal wear
Show answer & explanationAnswer & explanation
Correct answer: C. Imbalance in a rear wheel assembly
Vibrations felt in the seat and floorboard at higher speeds are typically indicative of an issue with the rear wheels, such as an imbalance. Front wheel issues usually manifest in the steering wheel.
Why the other options are wrong
- A. Worn front suspension components would likely cause noise, wandering, or a front-end vibration felt in the steering, not typically the seat.
- B. Excessive toe-in primarily causes tire wear and a pull, not a seat vibration.
- D. Steering rack wear would generally cause loose steering or clunking, not a vibration in the seat and floorboard.
Rear Wheel Imbalance Symptoms
An imbalance in a rear wheel assembly causes vibrations primarily felt in the seat, floorboard, or entire vehicle, especially at higher speeds.
- Vibration felt in seat/floorboard
- More pronounced at highway speeds
- Distinct from steering wheel vibration
Memory trick: Seat and floor = rear, Steering wheel = front.