I was changing the u-joints on the front axle of my TJ tonight and was using a u-joint/ball joint press to push them in and out (great tool by the way, if you don't have one they are worth the $30-$40 they cost at Harbor Freight). I was a hair from having the last cap in far enough to put the clip in and just couldn't muster the strength to get it in any farther, so I said screw it and picked up the impact and gave it a quick shot. It moved just enough and I put the clip in and turned the impact to reverse and backed the press off, as I did that the end of the opposite cap went shooting off. Not the whole cap mind you, just the flat edge where it broke off the cap.
Moral of the story: NEVER USE AN IMPACT WRENCH ON A U-JOINT PRESS!
Looks like I'm definitely riding the motorcycle to work tomorrow!
I have another u-joint but it's for the other side which I actually think is bad (that's the part that really bites my ***, the u-joint I was replacing wasn't even bad. I pulled it apart and it looked OK, but thought I may as well go ahead and replace it because I don't know how old they are.). I'll stop tomorrow and pick up another one and see if I can get it back together.