They Said It Can't Be Done...Or Don't Even Try

whitepunkonnitro said
It looks good...but I'm one of the guys who recommended he not go this far with this car. Here's why...and PLEASE, I don't mean to be a downer or piss on anybody's parade. I'll just pass this on to anybody who might be considering this sort of reconstruction.
These cars are spot welded together at the factory. The design of the panel and their support is predicated on that sort of welding. When you cut a car apart like this and weld it back together with anything but spots or TIG, the welded seams are much harder than the metal surrounding them. When changing a quarter, or a floor pan, it's not a big deal. But, the roof structure is an active part of this cars chassis. If you've ever cut the roof off a hardtop and tried to lift the car, you'd see just how much rigidity the roof adds. As this car rides over bumps, and goes through cornering and stopping motions, the soft original metal will want to move slightly as it was intended...the hard seams will not. It's just a short time before those areas become work hardened and begin to crack. In the event of a serious accident, the metal will tear like tissue paper along the seams. There's a lot to this!
I would say that adding a pair of GOOD frame connectors and a pair of Torque Boxes as would be found in a convertible would be a seriously good investment for this particular car.
Again, just my 2 cents. Not taking anything away from your efforts or accomplishment. Just wanting to make sure your investment stays looking good and is safe.

Definitely a valid point. MIG welds are more brittle than other types of weld, at least in the general sense. That's also not to say that there's nothing you can do to reduce (not eliminate) that situation.

But I think in this particular case the point may be overplayed a bit. All of the roof structure kept it's original spot welds. By taking the replacement all the way out to the cowls, the forces are diffused quite a bit. There's a lot of area, and a lot of weld locations, by going all the way out to the cowls as was done here. If the roof was removed by just lopping off the A and B posts and welding around them, I would be a heck of a lot more concerned about the welds.

That's not to say I wouldn't install frame connectors or torque boxes. I think those are a good idea for ALL of these cars, as they were pretty flexy from the factory. And in this particular case I think it would be good additional protection considering all the work that was done. But I don't think you'd see cracks around all of those welds in short order, or that the car would have a systemic failure in a crash if those precautions weren't taken simply because of the area that those forces are spread across in this particular instance.

I'd still add the frame connectors and torque boxes though. :D