The cast iron outer faces of the brake disk hubs and also the brake calipers on my 2007 335i coupe have rusted significantly in places. Although the rust appears to be just a surface accretion, and the metal itself appears not to have been pitted, it is quite unsightly and can be seen through the wheel spokes. I have seen the same corrosion on many other 335is as well. Does anybody know how I can treat the metal surfaces to remove the rust and prevent it from reappearing?
Had the same problem on my 330Ci when I had it and put new wheels on it. What I ended up doing is cleaning the rotors (seemed to be only the front rotors that had this problem) good with brake cleaner and spraying the rusty area with VHT Hi-Temp paint. Any overspray that may have gotten on the rotors was scrubbed off the first time I hit the brakes. Looked good and seemed to hold up fine. Never did anything with the calipers, but I'd guess that would be a bit more complex job. I considered powder coating them never followed through.
Thanks for your help... Thanks a bunch for your helpful suggestions. I'm going to try this at the first opportunity. The rotors are much worse than the calipers so I'll try those first with your cleaning and spray painting method. I'm going to have to think hard about whether to powder coat finish the calipers since this will require significant downtime for the car while the job is completed. I'll probably end up doing it in the end though. What amazes me is that these finish treatments weren't completed during manufacture of the car, since the problem is widespread and affects the appearance of the car. I guess it all comes down to the cost of manufacture and a decision by BMW to cut that in any way they can. Another example is their production and sale of the car in 2007 with a twin turbocharged engine and no oil cooler. But that's another topic, unrelated to this forum.
I can't take credit for this idea. A BMW Master Tech suggested it. We actually had the car up on the lift doing some other maintenance and he let it idle in gear with the back wheels moving and sprayed the rusty area. He then spun the front wheels and repeated the process. (Thanks to Jim at BMW of Nashville...)
