I think it's been over 30 years since I've ruined a festener by cross-threading...until the other night. [img]images/icons/frown.gif[/img] I was doing the simplest of tasks: attaching my rear calipers to the mounting ears on the uprights. I was having a hell of a time getting the cap screw to match up with the hole in the upright, and was trying to "pursuade" it with a wrench. The threads caught, and at first seemed OK but then started to feel "funny" and it got harder to turn. I ignored the little voice inside my head that was screaming at me and cranked it down. I realized I was in trouble when I tried to back it out. I was afraid I would break my 3/8" ratchet after I was putting enough force on it to lift the chassis off the jackstands (probably around 200 ft-lb). Since I only had one 10 mm Allen socket and it was for a 3/8" drive ratchet, and I had no breaker bar, I gave up for the night.
On the way home from work tonight I saw a Matco Tools truck and flagged the guy down and bought a 1/2" drive 10 mm Allen socket (and a couple other little goodies [img]images/icons/wink.gif[/img] ). The screw came out no problem with my big breaker bar, and boy is it messed up. Here's a pic:
As you can see, I trashed not only the cap screw, but the mounting hole in the rear caliper. The metal around the hole actually has a little lip that I hit with a file so it would show up. I think the root cause of the problem, other than my carelessness and impatience, was the fact that the calipers are powder coated (clear) and I think the powder coating in the hole in the mounting ear reduced the oversize of the hole such that it was impossible to get a good alignment. It would've been easier to pop the rotor off and relieve the hole a little with a round file, but then again hindsight is always 20/20.
Any recommendations how I should proceed? Should I just drill out and tap the hole for the next-larger size fastener? Should I see if a machine shop can repair it? I don't think this will warrant me getting a new caliper. Any input appreciated.