I've got a '66 122s for a daily driver with stock calipers and wheels and on my drive home yesterday, when I would apply the brakes, I would hear a loud smacking/scraping sound that sounded like it occurred at wheel 1/rev. Along with the loud sound I would also feel the car shake. Upon inspection of the brake caliper, I noticed that there was metal removed from the caliper and matching wear marks on the inside of the wheel rim. Any theories on how this could happen?

Some other background, two months ago I changed the brake pads, caliper hardware, had the rotors resurfaced at a big box auto chain, cleaned and re-greased bearings, and reassembled. While everything seemed to be working fine, I noticed that the wheel would get hot after a long drive. So last weekend I inspected the caliper and noted one of the lock clips was missing from the guide pin and the damping spring of the outboard pad was nowhere to be found. I promptly replaced it with the old hardware I had leftover from two months ago and after driving about 25 miles the caliper is now contacting the wheel rim intermittently while braking (and only while braking, I tried coasting and down-shifting to alleviate the brakes on my way home both of which produced no "noticeable" contact).

I'll probably spend the better part of the Thanksgiving weekend working on it so any help to identify the culprit would be much appreciated.

Thank you.
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Andy - '66 122s, '03 Trailblazer