Deep, permanent stains/etching on inside of rims due to dripping brake pad acid?

[imported_sydster]

Well, maybe I should not be jumping to conclusions, but that sure looks like what it is from. Why it happened only once, I am not sure.



It is so hard to remove that I thought it might have been from the casting process or an application of strong wheel cleaner, but the exterior chrome would show some damage, and it remains in fine shape. Anyway, here are some pics to show you what I am talking about.



They all have a drip-like pattern, starting at the centerline of the wheel and then migrating towards the (lower) inner edge, which suggests gravity was at work (hence the dripping-from-the-calipers theory), and resisted all removal attempts, including scotch-brite, steel wool, wire-brushing and sandpaper.

http://www.clublexus.com/gallery/data/500/2438rims010.jpg

http://www.clublexus.com/gallery/data/500/2438rims017.jpg

http://www.clublexus.com/gallery/data/500/2438rims012.jpg

[danwatt]

Could be a leaking caliper. Brake fluid is pretty serious stuff. Do all the wheels look like that?



Either that, or... is your car blue, by any chance?

[imported_sydster]

Car is not blue and I don`t know where that blue you see in the photos came from, but it`s not on the rims. Yes, the stains are, to some extent, on all 4 rims. Below is another one- you can see the same stain on the right side. It`s not likely brake fluid- what are the chances of all 4 calipers leaking at some stage, and then, only once per wheel, when the car was stationary?



But you are in the right track- you can tell by the way the stains form that whatever it is likely dripped down from the caliper area, pooled onto the inner wheel, then flowed down onto the tire.

http://www.clublexus.com/gallery/data/500/2438chrom002.jpg

[Setec Astronomy]

It`s a little hard to tell, but I would say that`s an artifact from the plating process. The manufacturer probably didn`t care since it`s on the inside. If it was wheel cleaner, I would expect that overspray/drip would have been on a larger area. It`s not uncommon for parts in plating tanks to have an air bubble which prevents plating in certain areas, or for some plating solution to remain on the part after it is removed, causing damage to the base metal. That`s my 2 cents.

[SpoiledMan]

Yep, what Setec said.

[imported_sydster]

Yep, that sounds about right.



Mystery solved- thanks, fellas!



FY- I ended up painting the insides with silver metallic and clear coat. Those stains are now encapsulated and never to be seen again! Details on the process are at: http://autopia.org/forums/showthread.php?s=&threadid=52906