Welding prep for Porsche GRV panels

[Iciclehead]

Hi guys, just in the process of welding in the front bulkhead that will turn my '89 into a long hood. The new bulkhead I am using is a Porsche GRV part, which means it is galvanized and painted in their black primer.

Been trying to spot/plug weld it with my MIG, but the welds are not turning out as I like, fair bit of popping and poor penetration.

I was wondering if the problem was the Porsche primer/galvanized coating. Since these are mainly spot welds, I did not grind the primer off, theory being that I want as much rust protection as I can get.

What have other people been doing? I see a lot of welding going on and some fine workmanship - are people generally grinding off the primer prior to assembly or are they cleaning it through the holed panel or just burning through the stuff.

Commentary is appreciated....and yes, I have been playing around with wire speed and voltage, using Argon gas in this case...

Thanks

Dennis

[Fixer]

I learned to weld 20 years ago on the 356 in the photo behind my FJ-40

(been dying to show this photo)

The galvanization has nothing to do with a bad weld unless it's preventing a good contact.

I would rather have a very good weld than worry about the primer burning away. Try and find a way to get primer in those places afterward.

I used to try an replicate pinch welds like you are trying to do by drilling a 3/16" hole through and filling with weld.

I have found they look good but not as strong as laying a short 1/2" bead.

Anyway, be sure you have a good ground between both the car and the new bulkhead, crank up the juice, lay a good short bead where you think appropriate to connect the two parts and due the same on the other side for symetry and then try your fill welds.

Bad weld must be a contact issue or gas issue.

[Daves911L]

Dennis,
Galvanizing can and does produce weld sputter and popping. I have never tried to weld on a Porsche GRV panel, but I've experienced this with the RD galvaneal panels, and some other non-porsche welding tasks. Higher current/gas flow makes it better. But I prefer to clean all primer/galvanize away from the area where I intend to be welding with a small grinder/abrasive pad. Nothing welds as nicely as two pieces of fresh shiny clean steel!

[Flieger]

Zinc fumes are toxic, so be very careful and make sure you remove the galvanizing far enough around where you are welding.

[slcarr]

If it is galvanized I get it off of the area with muratic acid although it is nasty stuff to work with, wear a charcoal mask. It is probably better to do that than breath the fumes from the galvizing, have also found if you weld with galvanizing on and you get it to hot the weld will crystallize.
Steve. been restoring cars 43 years.

[Iciclehead]

Great advice guys and thank you. Must admit I learned how to weld when I was about 11 (my dad had a welding shop), but it was all stick welding and on nothing much thinner than 1/4 inch plate! This sheet metal stuff and MIG is certainly fussier.

I think what I will do is grind the primer/zinc off where the spots are going to go, raise the voltage a bit as well as the gas flow. I will also put some bead welds on the edges of the panels, which incidentally Porsche did as well (as I found out to my chagrin when I took the short hood bulkhead out).

Also I'll be quick with the grinder if needed....I will be posting pics on my 6 speed Carrera thread....

Oh yes Fixer, that 356 in the background, is it on the road or is this an old picture? If I see it right it is tipped on its side...

Thanks again all,

Dennis

[Fixer]

I hope it is on the road still, it is a "B" originally black and currently i guess with biscuit leather and a electric sunroof. Normal motor.
The owner left it sitting outside and a small tree was growing thru it when he had us restore it. This was in the mid 90s.
pictured, it is on a rotisserie (sp?) we made out of 1/4" plate and square tube.
It has been gone a while. I have no finished photos, pre digital.

BTW i use 75% Argon 25% carbon dioxide and when welding galv steel simply scrape a little galv away with a sharp tool before welding.

Do have one of my FJ, wish i kept it.

Good luck with your welding and please post pictures.

Matt