ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A technician is performing a diagnostic on a vehicle with a double wishbone front suspension. The customer reports a noticeable 'creaking' or 'squeaking' noise, especially when driving over uneven pavement or speed bumps at low speeds. The noise is intermittent and seems to come from the front right side. After a visual inspection, no obvious damage or leaks are found. Which of the following is the MOST appropriate next diagnostic step?
- AReplace the front right shock absorber.
- BPerform a load test on the front right coil spring.
- CCheck for proper torque on all suspension fasteners.
- DLubricate the control arm bushings with a silicone-based spray.
Show answer & explanationAnswer & explanation
Correct answer: D. Lubricate the control arm bushings with a silicone-based spray.
Creaking or squeaking noises from a double wishbone suspension, especially over uneven surfaces at low speeds, are very common symptoms of dry or worn control arm bushings. Lubricating them can temporarily silence the noise and help confirm the diagnosis before replacement.
Why the other options are wrong
- A. A faulty shock absorber typically causes a knocking or thumping noise, or affects damping, not usually a creaking/squeaking noise.
- B. A load test on a coil spring is for ride height or spring fatigue issues, not typically for creaking/squeaking noises.
- C. While checking torque is good practice, loose fasteners would more likely cause clunking, not creaking/squeaking, and the noise is intermittent implying friction, not looseness.
Bushing Squeak Diagnosis
Squeaking or creaking noises from suspension often indicate dry, worn, or binding rubber bushings. Lubricating them with a silicone spray can temporarily alleviate the noise, aiding diagnosis.
- Caused by dry/worn rubber bushings
- More common at low speeds/uneven surfaces
- Silicone spray can temporarily confirm source
Memory trick: Creaking and squeaking, a bushing's sad plea, spray it with silicone, then you will see!