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I'm building a Pantera GTS purely for racing and want to seam weld the chassis. Can anyone give me any insights on doing this? Such as where to stitch weld? Where to add strength? What panels should be doubled up to reinforce etc?

I've read about the rigidity frames so please don't tell me to just use those as the main two reasons I have for seam welding are:
1. Chassis strength helps suspension tuning and handling
2. Seam welded chassis protect the driver in an accident far better than OEM spot welding.
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The weak spots are where panels overlap and are only spotted together, as below the tail lights, at the vertical leading edge of the inner rear fender panels (up thru the rubber insulator channel) and at both ends of the windshield posts (these last also need doublers welded in). Then do all the crossmembers in the rear subframe, and add doublers where the lower front subframe rails attach to the tub. Along the way, I'd seam-weld every big panel I could reach- especially the outer fenders and the whole roof. You'll likely have to paint-strip the entire car to do this, and anyplace where you find popped spot-welds is a red flag that that area was overstressed, so it also needs seam-welding. I'd suggest doublers where the suspension a-arms fasten to only thin sheet metal tabs- these have cracked under racing stresses with giant tires. Good luck- you'll have a truly super-car once this is done!
Da Bosswrench knows his stuff. Years ago I was thinking of getting a car and restoring, so I came accross these reinforcement pieces shown in the photo, I believe for the pillar area by the decklid/roof line. They have a slight curve to them when you lay them flat, almost as if someone took an english wheel to them. Measurements are shown too.


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Hello, Australia. On the other side of the planet I´m doing almost the same thing. I´m fixing and at the same time reinforcing my 1977 gts, but mostly for normal street use. I will be adding lots of little plates in several places, and also doing seamwelding whereever I can. The whole car is in bare steel at the moment. The structure for 1977 Pantera looks quite different, but all the problem areas are obvious. Could it even be, that all that use of straight steel and sharp corners in later Panteras causes even more cracks than those smoother shapes used in early Ford era Panteras?
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