I am getting ready to weld on a set of subframe connectors on my '69 Fastback and I've read that the car has to be sitting on the wheels, axle or lower control arms to keep from flexing the body.
My car has small cracks in the paint at the top of the A-Pillar and on the rear valence panel between the tail lights - both signs of excess body flex.
My thinking is that if one were to place the subframe connectors into place and then put some upward force on them (unload the unibody and suspension by a few hundred pounds) prior to welding them so that some of the 40+ years of body sag may be reversed. Why would you want to leave the sag in the unibody and then lock it in with subframes? Wouldn't it be better to reverse the sag and pretension the subframe connectors?
As a mechanical engineer, this makes sense but I keep reading that I shouldn't do this... can someone please explain why?
My car has small cracks in the paint at the top of the A-Pillar and on the rear valence panel between the tail lights - both signs of excess body flex.
My thinking is that if one were to place the subframe connectors into place and then put some upward force on them (unload the unibody and suspension by a few hundred pounds) prior to welding them so that some of the 40+ years of body sag may be reversed. Why would you want to leave the sag in the unibody and then lock it in with subframes? Wouldn't it be better to reverse the sag and pretension the subframe connectors?
As a mechanical engineer, this makes sense but I keep reading that I shouldn't do this... can someone please explain why?