Going to have to replace some floor pans have a question

[spankybear]

My LMTV has more holes in the floorboards than I want to deal with. I am going to replace the rusty parts. So when you remove the rusty parts and you are going to install the replacement. How do you prep/seal the exciting structure/flanges. I am not to sure what it's called but the parts that the floor pans is spot welded. The braces, brackets, body ect. There are flanges that are spot welded. I don't want rust to start there. Since I am going to be welding I can't paint it. Is there a way to stop and or prevent these areas form rusting? I sure hope I am making sense. This is uncharted water for me. But not out the realm what I am willing to tackle.

 

[kblazer87]

https://www.3m.com/3M/en_US/company.../3M-Weld-Thru-II/?N=5002385+3293194153&rt=rud

Found this with google.

 

[spankybear]

https://www.3m.com/3M/en_US/company.../3M-Weld-Thru-II/?N=5002385+3293194153&rt=rud

Found this with google.

Have you used this before? How well does it work? Is there any issues you had using it?

 

[redmudjeep]

Weld-thru primer is what you want. Used it 20 years ago when I worked in a body shop. I am sure it is improved from then.

 

[nyoffroad]

Have you used this before? How well does it work? Is there any issues you had using it?

I've used it, works good but splatters a LOT, shake well then shake some more, when you think your done shaking shake for bit more because the tip clogs easily! Also works great on exhaust pipes to keep them rust free.

 

[CMPPhil]

Not all Weld Through primers are created equal

I've used it, works good but splatters a LOT, shake well then shake some more, when you think your done shaking shake for bit more because the tip clogs easily! Also works great on exhaust pipes to keep them rust free.

Hi Guys

Not all weld through primers are created equal. I have been working on a restoration project not MV that has required extensive welding of newly made body and structural parts. In doing this I have tried several, though not all, of the different rattle can weld through primers.

Couple of different issues:

What are you welding with, mig, tig, or pinch spot welding. Different ones seem to work better than others depending on the type of weld. Have not tried it with oxy/ace

Are you welding clean fresh steel to clean fresh steel, or new steel to existing metal with some surface rust.

NAPA- Zinc Weld Thru Primer 7221- Good rust protection after the weld, have a sample hanging out in the drip area from the shop roof, gets wet when it rains, several years painted area no rust. Spot welds nicely, but mig weld it is hard to get a smooth weld even on fresh steel to fresh steel, lots of splater.

SEM 40783 Copperweld is the best I have found, quite frankly after finding things I stopped looking. Spot welds very well, mig welds nearly as smooth as bare fresh steel.

Now as to what chemicals either of these are giving off when welding no idea. I always use a supply air welding helmet for welding anyway. Would recommended good ventilation.

Cheers Phil

 

[Warren Lovell]

Make sure you use a seam sealer on replacement metal joints if you are not circumference welding the patch. Seam sealer cannot be applied over an etching primer...fyi. So if you etch it, spray it with epoxy primer and then seam seal it...or buy the seam sealer that is direct to metal applied...then prime and paint.