ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A technician is diagnosing a vibration that is felt primarily through the steering wheel at speeds between 45-60 mph, but tends to diminish at higher speeds. The vibration is present during acceleration and coasting. The customer recently had new tires installed and balanced. Which of the following is the MOST likely cause of this vibration?
- AImproperly balanced front wheels.
- BAn unbalanced driveshaft.
- CA bent rear wheel.
- DA severely worn wheel bearing.
Show answer & explanationAnswer & explanation
Correct answer: A. Improperly balanced front wheels.
Vibrations felt primarily in the steering wheel at specific moderate speeds, diminishing at higher speeds, and occurring during both acceleration and coasting, are classic symptoms of improperly balanced front wheels.
Why the other options are wrong
- B. A driveshaft imbalance typically causes vibrations felt through the seat and floorboard, not primarily the steering wheel, and often increases with speed.
- C. A bent rear wheel would typically cause a vibration felt through the seat and floorboard, not primarily the steering wheel, and might be more consistent across speed ranges.
- D. A severely worn wheel bearing usually causes a growling or humming noise that changes with speed and cornering, and can also cause looseness, but not typically a steering wheel vibration that diminishes at higher speeds.
Wheel/Tire Imbalance
Wheel and tire imbalance occurs when the weight distribution around the wheel's circumference is uneven, leading to vibrations, especially at certain speeds.
- Front wheel imbalance: steering wheel vibration.
- Rear wheel imbalance: seat/floorboard vibration.
- Often speed-sensitive, can diminish at higher speeds.
- Requires proper wheel balancing with weights.
Memory trick: Where do you feel the shake? Is it speed-sensitive or engine-speed sensitive?