Odd rear brake wear

[WAKman]

The passenger side rear brake rotor of my car has this odd wear pattern. It previously was occurring on both sides, so I replaced the pads. The left side seated correctly (top pic), but the right did not (lower pic). I'm wondering if anyone else has experienced this. The correct thing to do, of course, would be to take it all apart, clean the caliper piston, and get it all sorted. But I'm a bit pressed for shop space and don't want to do all that outdoors.

Another odd thing is that the retaining clip, present in the right side, is missing from the left side (top pic). I recall hearing an odd rattling before noticing that it was gone--as was the clip. I'm not sure exactly what those clips do, as they were sort of loose in my car--obviously, since one fell off. I doubt they are related to pad seating and wear, but perhaps they are. Anyone know?

[WAKman]

And yes, I know my wheels are horrible looking. That will change when I get my shop space back.

[kevin @ eas]

The clip you are missing is an anti rattle clip. I would check the caliper guides/slide pins to make sure they are alright first. Thats normally a cause of uneven rotor wear or the pads being worn.