When you start hearing a rattling noise near the tires, you tend to get a little concerned. With barely 50,000 miles on our car, the caliper fell out of place. The caliper starts beating against the tire whenever we get up to 60 mph. Our mechanic moved the caliper back into place, but not until after several other mechanics (including GM itself) told us we were crazy. A few months after having it fixed, it was back to making that noise again, and it only gets worse. From what we understand, this caliper has the potential to interfere with the brakes, making it definitely a problem we just wish would go away. But then again, that's GM for you.