ASE G1 Auto Maintenance and Light RepairSuspension and SteeringMedium
A vehicle exhibits a vibration that is felt primarily in the seat and floorboard, rather than the steering wheel, and becomes more pronounced at higher speeds (e.g., above 50 MPH). The vibration does not significantly change when turning. All four tires were recently balanced. What is the most likely cause?
- AWorn front wheel bearings
- BBent front wheel rim
- CUnbalanced rear wheels
- DUnbalanced front wheels
Show answer & explanationAnswer & explanation
Correct answer: C. Unbalanced rear wheels
Vibrations felt primarily in the seat and floorboard, especially at higher speeds, and not significantly in the steering wheel, are characteristic of an imbalance in the rear wheels. Front wheel imbalances typically transmit vibration through the steering column to the steering wheel, while rear imbalances are felt more broadly through the chassis.
Why the other options are wrong
- A. Worn front wheel bearings typically produce a growling or humming noise that changes with speed and sometimes turning, but not primarily a vibration felt in the seat/floorboard without steering wheel input.
- B. A bent front wheel rim would likely cause a vibration felt in the steering wheel, similar to an unbalanced front wheel, and could also cause a pull or abnormal tire wear.
- D. Unbalanced front wheels typically cause a vibration felt strongly in the steering wheel.
Rear Wheel Imbalance Vibration
Vibrations felt in the seat and floorboard, particularly at higher speeds, with minimal steering wheel vibration, typically indicate an imbalance in the rear wheels.
- Front imbalance = steering wheel vibration.
- Rear imbalance = chassis/seat vibration.
- Speed-dependent.
Memory trick: Seat Shake? Rear Wheel Mistake! Steering Shake? Front Wheel Ache!