If a person were installin fenders with flares or box flares or an IMSA kit or whatever.....What can safely be removed from the existing sheetmetal? I know the front is a simple unbolt/replace situation, but what about the rear? I don't want to just 'go over' the existing metal fender. To truly lighten, some of the existing material must have to come off... But what can be removed safely without damaging the structural integrity of the body system? I can't imagine the new fibreglas fender (blended in) will provide anywhere near the rigidity of the original.

Can somebody clue me in?

steve77

Without a full roll cage tied into the rear strut towers, you cannot remove the rear quarter panel or you will seriously compromise the unibody's strength. When I flared my two Z's I removed the springs and moved the suspension up to determine how much to cut out of the inner and outer fenders. After cutting the fenders I pounded up the inner fender, added a curved rod where the inner and outer fenders met (to make it easier to weld) and welded every inch or so. Do not continuously weld or you will warp the outer panel. (Don't ask how I know this). I trimmed off the excess inner fender and painted. I also had the gas tanks out when I did this.

Here is a pic.

You can cut the fender and weld a plate between the gaps, this is what the 250 GTO kits do.

and