ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle equipped with a double-wishbone front suspension exhibits a noticeable 'squeak' or 'groan' noise when going over speed bumps or turning slowly. The technician performs a visual inspection and notes that the lower control arm bushings appear intact with no visible cracks or tears. However, while bouncing the suspension, the noise is consistently reproduced. Which of the following diagnostic steps should the technician perform NEXT to pinpoint the cause?
- ALubricate the control arm bushings with a silicone-based spray and re-evaluate the noise.
- BPerform a four-wheel alignment to check for geometry issues.
- CReplace the sway bar end links as a preventative measure.
- DCheck for loose wheel nuts and torque to specification.
Show answer & explanationAnswer & explanation
Correct answer: A. Lubricate the control arm bushings with a silicone-based spray and re-evaluate the noise.
Even if bushings appear intact, they can dry out internally or lose lubrication, leading to squeaking or groaning. Lubricating them with a compatible spray can temporarily eliminate the noise, confirming the bushings as the source without immediate replacement.
Why the other options are wrong
- B. An alignment addresses geometry and tire wear, but won't diagnose a specific squeaking noise from a dry bushing.
- C. Replacing parts without proper diagnosis is inefficient; sway bar links usually clunk, not squeak/groan from dry rubber.
- D. Loose wheel nuts typically cause a clunking, not a squeak/groan, and would be felt as wheel looseness.
Suspension Bushing Squeak
Suspension bushings, often made of rubber, can dry out or deteriorate, causing friction between the bushing and its metal sleeve or mounting point, leading to squeaking or groaning noises, especially during suspension movement.
- Common in control arm, sway bar, and shock mount bushings.
- Often more noticeable in cold or dry weather.
- Lubrication can temporarily silence the noise for diagnosis.
Memory trick: Hear a 'SQUEAK'? Spray and 'SEEK' the source!