Weld through primers

[Prowe]

I'm doing a full restoration on a 1981 Trans Am in which I'm doing full floor pan replacements on! I've heard so many different opinions about using it and not using it that I'm more confused than ever! I'm not a professional welder so I'm looking at what's going to be easier but I also want to do a good job! Here are my questions.....

1. Is it necessary?
2. If it isn't what steps do you recommend for future rust protection?
3. Which one do you recommend
4. How would you use it?

Thanks!

 

[Barry]

Any lapped panels should have this applied to both panels being welded.
All the brands are good and most aero cans of this are 90-97% zinc, the more zinc the less sparks.

 

[Barry]

Any lapped panels should have this applied to both panels being welded.
All the brands are good and most aero cans of this are 90-97% zinc, the more zinc the less sparks.

 

[Prowe]

So that would mean the front where it overlaps the toe board panel! What about where the pan is attached to the cross member and down the rocker panels?

 

[stangnet33]

What about panels that come with it already sprayed on ? Been hearing/reading about complaints of rust starting to appear even before the panel is installed. Paying the extra bucks for it only having to sand it all off.

 

[anotheridiot]

How are you welding the parts together? I really only hearing this is good for spot welding. If you are mig welding the panels together I think the heat is alot higher and it will bubble.

We did full floors and rockers on the camaro, we actually powdercoated the new parts, masking the edges and ran full beads.

- - - Updated - - -

How are you welding the parts together? I really only hearing this is good for spot welding. If you are mig welding the panels together I think the heat is alot higher and it will bubble.

We did full floors and rockers on the camaro, we actually powdercoated the new parts, masking the edges and ran full beads.

 

[Prowe]

I'm mig welding

 

[anotheridiot]

I'm mig welding

I would think its less important to have the primer then. If you are spot welding every 6", there is plenty of gap to want that protection. We did ours on a rotiseree we built, so it was easy to flip and weld from both sides so we ran full beads across, ran a 3" bead every 6 inches or so, then went back and filled the gaps between. any gaps left were just sealed with seam sealer to keep the elements out of the joint to protect it from rusting after the bottom was repainted.

Our beads were only bad where the powder was too close to the weld, but we run flux core so its a bit sloppier if there was any powder present.

I guess all I am saying is if you are running more weld than where spot welds were on the original car, I dont think its as important to have it on the parts.

- - - Updated - - -

I'm mig welding

I would think its less important to have the primer then. If you are spot welding every 6", there is plenty of gap to want that protection. We did ours on a rotiseree we built, so it was easy to flip and weld from both sides so we ran full beads across, ran a 3" bead every 6 inches or so, then went back and filled the gaps between. any gaps left were just sealed with seam sealer to keep the elements out of the joint to protect it from rusting after the bottom was repainted.

Our beads were only bad where the powder was too close to the weld, but we run flux core so its a bit sloppier if there was any powder present.

I guess all I am saying is if you are running more weld than where spot welds were on the original car, I dont think its as important to have it on the parts.