[Vic1947]

I've never had any luck straightening out the factory clamshell lip that holds the doorskin to the inner panel. They make tools (cheap and expensive) that are supposed to be the hot tip, but I've never found one that truly works. Every time I've tried to work the lip back up to a 90 like you get on a new doorskin, I end up damaging the edge and making more work for myself than it's worth. Anytime you bend metal, it work hardens. Just take a piece of scrap, put a 90 degree bend in it and then try to flatten it back out. You have to beat it into submission.

So the approach I use is to take a cutoff wheel and remove all but about a quarter of an inch of the folded over lip. Cut all the way thru the lip and the inner panel structure, but not thru the outer skin. Remove the lower part of the inner door panel you're going to replace to give you better access. Then carefully pry up a corner to expose the trapped strip of sheet metal left behind. I grab it tight with a pair of vise grips, then start tapping the grips with a small brass hammer to work the strip out of the recess. It will take several attempts to remove the entire strip and I usually reset the grips every few inches. Once it's out, I use a thin cutoff wheel in my Dremel tool to gently clean out the rust and debris from the groove.

You end up with a small recess around the perimeter of the door that, from the outside, doesn't look like it was ever disturbed. On the backside, I then trim the replacement panel to slip into what is left of the recess. Once the rest of the panel is fitted into place, I tack weld the lip to the replacement panel every few inches and then use seam sealer to finish up. Welding it solid may warp the skin, so I try to avoid that.