Quote:
Originally Posted by mjk3888
Its not about applying grease to cause movement. Its about cleaning the corrosion off and a LIGHT coat of something to prevent the return of the corrosion.
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Corrosion does not explain my observations with respect to the clicking noise. To reiterate...
- Received the car from the factory with pronounced repeated clicking noise with moderate loading in turns in both directions
- Torqued lugs to spec (140ftlbs). They were noticeably loose. Pronounced clicking noise still present, but at higher loads in turns in both directions.
- Removed wheels, and found a light film of grease and no signs of corrosion on the wheel to brake hat mating surfaces (some surface rust on hub pilot that centers the wheel, but the hub pilot doesn't support the wheel load). Sprayed with brake cleaner and wiped mating surfaces down (quick clean-up). Pronounced clicking noise still present, but only in left turns now.
- Thorough clean-up of mating surfaces of all 4 wheels with lacquer thinner (multiple wipe-downs) until zero signs of grease on clean rag. Clicking noise completely gone under all cornering loads in both directions
- 5000+ miles later and zero clicking noise
I also noticed wear marks on the hub pilot. It appears to me that grease on the mating surfaces that GM applies reduces the friction to the point that it allows the wheel to shift around on the hub under load, and the clicking noise is likely coming from the wheel striking the hub pilot. I have a hard time believing the corrosion hypothesis because it seems unlikely that corrosion would result in a lower coefficient of friction than grease. It seems more likely that application of anti-seize eliminates the noise either because it reduces the friction to the point that the impacts on the hub pilot are less severe, or the anti-seize used happens to have a higher coefficient of friction than whatever grease GM applies. Regardless, the mating surfaces on my car have had zero grease for an extended period of time now, and if corrosion were indeed the cause of the clicking noise, it's had plenty of time to form and the clicking noise should have returned and be even worse now. But it has not returned.
It's possible that there are two causes leading to a similar phenomenon. I'd have to see a more detailed explanation of the mechanisms of the corrosion hypothesis to be convinced, which I've not found in this thread so far. Certainly open to the idea though. But based on current information, I feel confident in concluding that the clicking noise is, in most if not all cases, due to grease on the mating surfaces reducing friction in the clamped joint of the wheel to the hub to the point that a stick-slip action occurs. I suspect that those who still experience the clicking noise after cleaning did not have the mating surfaces cleaned thoroughly enough.
Nigel