ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A technician is performing a pre-alignment inspection on a vehicle with MacPherson struts. The customer reports a 'thump' noise when going over speed bumps and a general feeling of looseness in the front end. The technician observes that the upper strut mount is visibly collapsed and the rubber isolator is cracked. What is the MOST likely impact of this condition on vehicle alignment and handling?
- AIncreased negative camber and reduced ride height
- BIncreased positive caster and toe-in
- CReduced negative camber and increased ride height
- DDecreased positive caster and toe-out
Show answer & explanationAnswer & explanation
Correct answer: A. Increased negative camber and reduced ride height
A collapsed upper strut mount means the strut tower is effectively sitting lower relative to the spindle. This will pull the top of the wheel inward, increasing negative camber. Simultaneously, the vehicle's front ride height will decrease due to the collapse of the mount's structural integrity, potentially affecting other alignment angles indirectly.
Why the other options are wrong
- B. Increased positive caster generally improves straight-line stability, and toe-in is less directly affected by a collapsed strut mount.
- C. A collapsed strut mount would decrease ride height, not increase it, and typically increases negative camber, not reduces it.
- D. Decreased positive caster would reduce straight-line stability, and toe-out is not the primary direct effect of this type of failure.
Collapsed Strut Mount Effects
A collapsed strut mount can lead to increased negative camber, reduced ride height, and contribute to 'thumping' noises and poor handling.
- Affects static alignment angles.
- Compromises ride quality and stability.
- Can accelerate tire wear.
Memory trick: Mount collapse, wheel leans in, ride height drops, troubles begin.