In Reply to: What if... posted by JTS on March 12, 2001 at 08:42:17:
What needs to be done to regain structural integrity. I read your post, but more information would be helpfull.
Talk to bimmerworld. Barry does custom installs. He and I cut the rear out of his silver M3 years ago, then realized it wasn't the smartest thing to do. We welded in a bar that went from wheel well to wheel well, and that bar had two bars, 60deg apart that went foward/down and rearward/down to the frame rail. It's about 3" in from the edge of the wheel well. We used 1.5"x0.125" drawn-over-mandrel seamless 1020 steel tube--real rollcage tubing. We also used 0.125" steel plates to reinforce the floor of the trunk where the tubes met. The front tube went right to the spring perch. The rear was just added for extra footing. It probably did not do a whole lot for structure.
You could also get away with riveting an aluminum sheet in there. It should be about double the thickness of the original steel, nthicker than that is unnecessary. Use good structural rivets (the ones that leave the mandrel inside after you pop it) every 1.5". If you can get some good structural adhesive, use that in conjunction with the rivets. This may be a little les work than the welding. Remember that welding removes paint and undercoating, so you may get rust if you don't recoat the damaged surfaces.
Check out Barry's work at: