My c-clip fell out when I was turning into a Wendy's drive-through... I was coming up to the intercom and suddenly heard this wicked
grinding noise from the rear. I immediately stopped. When I got out and saw my left rear tire 8" out from where it should be I thought "that sucks..."
The c-clip didn't break, it was the lip of the axle that broke, thereby allowing enough "wiggle room" for the c-clip to fall out. The stock axles seem to have a lot of back and ofrth play in them, and I think that's why the lip ended up breaking. I bought a new pair of axles from JEGS and the problem was solved. Now I have a S60 though, so I don't have to worry about that