ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle equipped with a MacPherson strut suspension exhibits a 'boing' or 'twang' noise when turning the steering wheel at slow speeds. The technician inspects the strut assembly and finds no obvious damage to the spring or damper. Which component is MOST likely causing this noise?
- AWorn lower control arm bushing
- BSeized upper strut bearing
- CLoose sway bar end link
- DLeaking strut cartridge
Show answer & explanationAnswer & explanation
Correct answer: B. Seized upper strut bearing
A 'boing' or 'twang' noise during slow-speed steering, especially with a MacPherson strut, is characteristic of a seized or binding upper strut bearing. This bearing allows the strut to rotate with the steering knuckle; if it's seized, the spring winds and unwinds, causing the noise.
Why the other options are wrong
- A. Worn lower control arm bushings would typically cause clunking or creaking, not a 'boing' during steering.
- C. A loose sway bar end link would cause a clunking noise over bumps, not a 'boing' during steering maneuvers.
- D. A leaking strut cartridge would primarily affect ride quality and damping, possibly causing a knocking sound, but not a 'boing' during steering.
MacPherson Strut Bearing
The upper strut bearing allows the MacPherson strut and coil spring to rotate smoothly with the steering input. Failure can lead to binding and noise.
- Located at the top of the strut assembly
- Permits steering axis rotation
- Failure causes noise (boing/twang) and stiff steering
Memory trick: Strut's top bearing, a twisty tale, can make a 'boing' that's sure to wail.