Questions on welding up windshield seams

[BustedTruck]

Ok. So I want to weld up the seams like pictured below. The images are from bruce88's excellent build thread. http://67-72chevytrucks.com/vboard/s...=318544&page=4

My questions for all of you more experienced people out there are
Would I need to do it one tack at a time or can I just weld it up & not worry about the heat build up?


Does anyone have any pictures mid repair?

[clay68c10]

I’d go one or two tacks at a time. Sheet metal can move around a lot and you don’t want this warping.

[saxart]

Originally Posted by clay68c10

I’d go one or two tacks at a time. Sheet metal can move around a lot and you don’t want this warping.

I'd be very leery of building up too much and having a windshield not fit after that repair. It seems like a fix to a problem that doesn't exist. Why not just use a sealant and call it good? I used 3M 5200, which is an extreme caulk type material. It worked great, and it's not going anywere.

[HO455]

When welding sheet metal I always worry about heat. If your window frame is rusted like the one in the photos (very few aren't) you will need to do spot welds as you don't know how much material has rusted away underneath and the hotter you get the area the easier it will be to blow a hole through. The spot welds will also allow the impurities to come out and then you can grind them out. Play it safe and spot weld it up even though there isn't much of a distortion or warping problem in this area.
I wouldn't waste my time on rust convertors before welding as the heat of the welding will burn them away. Wait until you are finished welding. Just my opinions. Your results may vary.

[Ironangel]

Use a diluted muriatic acid solution to clean off rust before welding. A rust converter is a phosphoric acid based cocktail that converts iron oxide (rust) into iron phosphate. Iron Phosphate is an inert black compound that is sandable to a degree and accepts most paints, if done correctly the rusting process is all but stopped until the iron phosphate is chipped or scratched off. The key component in Navel Jelly and most all rust converters is Phosphoric acid. With that explained, you never want to use a converter before welding because iron phosphate wont allow proper penetration because it contaminates the puddle as well as the gas coverage. In those small tight areas such as those around the windshield, clean metal is the key as well as good fitting joints so you don't have to linger and overheat the weld area. Looks like you have a pretty good handle on it. If you use a "skip weld" technique it wouldn't hurt a thing to run one inch or one and a half inches at a time. You simply start your weld one inch ahead of your last pass and weld toward your last start. That method locks the metal in place and controls the heat as well as minimizes warping. Judging from your photos I'm guessing your rinsing the converter off before it dries, if so good idea because that stuff withstands incredible heat and don't play well with welding. I treated a set of rusty headers four years ago with phosphoric acid and they're still black...I'm a retired Iron Worker, unlimited certs in metals most folks never heard of, like Corten Steel and Inconel...

[BustedTruck]

Thanks for all your input. I think this is a worthwhile modification. This area is prone to rust on these trucks and not to mention looks a lot better too. Anybody else done this?

[darrellyates]

Originally Posted by BustedTruck

Thanks for all your input. I think this is a worthwhile modification. This area is prone to rust on these trucks and not to mention looks a lot better too. Anybody else done this?

Yes. I welded up mine, top and bottom. Also welded together and smoothed the drip rails. Considered lead in the drip rails, but settled on seam sealer similar to how it was done at the factory. Have searched for pictures, but don't have any specific to the area. It's in the paint booth right now or I would take a couple to show you. I like this. Just be sure the top seams are sealed; as most water entry happens there.