Welding Question

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rklein383

rklein383

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I am installing US Car Tools sub-frame connectors in my 71 Barracuda project.

I have prepped the floors with Rust Mort which has left the black oxide layer like it is supposed to.

Do I need to prep the weld area to be shiny bright metal before welding or is it okay to weld as is?

Thanks,
Rod
 
Weld area should be as clean as possible, especially if you're running small gauge wire with gas. Flux core will burn through some rust, but still, it's best of the area is clean.
 
The area is clean and the rust has been converted to a black oxide layer, I just don't know if I need to spend alot of time to make the area bright and shiny.
 
There is a welding primer out there that works great that you can weld on.
 
i you want nice neat welds clean it to shiney metal . wire feed welders dont like dirt it causes pin holes and other great things .
 
You want clean shiny metal for the reasons stated above. I also switched the polarity of my welder to weld upside down, which helped keep my puddle from sagging. I also used a stich welding technique that started the puddle on the frame connector and then continued it up onto the floor pan in a "C" pattern. If you have a brass block, it can be helpful to prevent the wire from blowing through the floor pan. I was lucky my car has no rust and the floor pan was still at it's full thickness. I did have to slot my torque boxes, and weld the connector to the frame inside them.

Another technique I used was to push the frame connector up against the floor with a floor jack, spot weld it on good at the corners and in the middle, and then I used a rubber mallet to pound the floor down a few millimeters here-and-there, where there were gaps and it needed to be closed to the frame connector.

This was how I did two sets of them, and it makes things a lot easier for me. I sealed the seams with 50 year paintable roof flashing caulking to protect the welds and seal any pin holes.
 
halifaxhops said:
There is a welding primer out there that works great that you can weld on.
Click to expand...

rament gave you the correct answer, weld through primer and oxide and you'll get a weld filled with porosity that won't be worth anything.
 
I would clean to bare metal the area about 1'' around where you are going to weld.
Not only will the welds be a lot better, it also eliminates the chance of you breathing in the fumes from the weld which would be nasty!
 
my advice is with mig welding is clean metal as stated above. I use the small .023 for things like thin floor pans, but you need .030 for the average frame connectors. I have cleaned surface rust with Ospho, which is phosphoric acid soluntion. the mig seems to weld there with no problem. the .030 is easy to bur
n thru a floor so you have to angle the weld more toward the frame connector if trying to weld the two. quick welds where burn thru is possible. I like the wire brush the welds, with a small wire wheel on a drill or whatever. then epoxy prime it all, then apply a good paint to seal it all.
I have used weld thru primer where I am welding patch panels. seems to work o k. time would tell???
I guess the main thing I have found with mig welding is it likes clean metal, NO rust or oil, any contaminant. adjusting heat, wire speed, proper size wire, good technique all important.
 
barbee6043 said:
my advice is with mig welding is clean metal as stated above. I use the small .023 for things like thin floor pans, but you need .030 for the average frame connectors. I have cleaned surface rust with Ospho, which is phosphoric acid soluntion. the mig seems to weld there with no problem. the .030 is easy to bur
n thru a floor so you have to angle the weld more toward the frame connector if trying to weld the two. quick welds where burn thru is possible. I like the wire brush the welds, with a small wire wheel on a drill or whatever. then epoxy prime it all, then apply a good paint to seal it all.
I have used weld thru primer where I am welding patch panels. seems to work o k. time would tell???
I guess the main thing I have found with mig welding is it likes clean metal, NO rust or oil, any contaminant. adjusting heat, wire speed, proper size wire, good technique all important.
Click to expand...


You answered my question in the middle - I can weld after getting rid of the surface rust with Oshpo (I am using Rust Mort).

Rod
 
Shiny metal, but to protect areas that will be hidden after welding, spray "weld-thru" primer. I used "high-zinc" spray paint from Home Depot or Ace, since I read it is basically the same as the specialty stuff.
 
I was leary of trying to mig weld where I had applied the Ospho. I 'm sure I cleaned the pitted metal first with a big wire cup on the right angle grinder, but was amazed how well it welded with that treated metal. if the metal had been fairly clean, not pitted I would have just cleaned the metal and welded, and then come bacl with epoxy primer and paint over the cleaned welds.
 
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