Quote:
Originally Posted by Vtor_ZL1
Found it! Here is back of brake rotor hat - notice all the corrosion marks on the anodized surface.
|
Fair point that anodizing won't prevent corrosion indefinitely, particularly if the anodized surface is penetrated, which can initiate corrosion prematurely. However, what's shown in that picture is very minor. It would take a substantial amount to compromise the clamping friction between the hat and hub to the point that the rotor is going to be able to move around enough to generate noise. To reach that level, I suspect the service life of the rotor itself would be well exceeded.
Further, the ticking noise that's common with these cars is there right from the start. It may take a while for an owner to notice it because it can take significant cornering loads that may not be achieved on the street. But regardless, it's apparent when the parts are brand new before any kind of meaningful corrosion could have formed.
The root cause for the majority of cases has been identified as improperly torqued lug nuts from the factory along with a film of grease that they were applying between the rotor face and the wheel hub (which they've hopefully stopped doing). The loose, lubricated interface causes the wheel to shift around under cornering loads and from my observations of shiny spots on the hub pilot, the ticking noise is coming from the wheel striking the pilot as the wheel shifts around. As
Msquared mentioned, lubricating the interface is not always a great idea.
Some people have been successful in eliminating the noise by simply fully torquing the wheel nuts. That made a meaningful improvement for me, but didn't eliminate it completely. I had to scrub the wheel and rotor interfaces spotlessly clean with lacquer thinner to get rid of the sound once and for all. That was years ago and it's never returned.