Here I thought the cars were spot welded together was because it was quick and cheap. I had no idea it was to enhance structural integrity.....go figure???
No...you misunderstood the point. Spot welding does not increase the structural integrity, but the WAY the panels are stamped and fit together, they are designed to be spot welded. That's why there are pinch weld seams and not just overlaps. The weld seam holds rigid, the metal around it is designed to flex.
Adding Mig seams alongside original spot seams is a double rigid and the closer they are to eachother, the more pronounced the load on the metal in between is. Those are the area I would be concerned about work-hardening in normal use.
From a safety standpoint, I'm not saying that this car is going to hit a bump, crumble and burst into flames. I'm sure it would hold up fine in a fenderbender, BUT, in any sort of severe impact, the metal adjoining the MIG seams ABSOLUTELY WILL rip like it's made of cardboard. I've seen this many times over the years where quarters and whatnot that were Mig'd, tore in an accident.
