Floor pan welding

[jb8376]

I am about to replace my front floor pans. I cant decide if i should butt weld or lap joint them. I wanted to get some of your opinions first. I am leaning towards butt welding them so you wont see them lapped from underneath and give a place for moisture to get in but i have read lapping them will be stronger.

Also, does anybody know how to remove the pan from the rocker. Is it put together with seam sealer or spot welded there? I only have a small place to patch on the rocker and dont want to bend it up while removing the pan. Any help is greatly appreciated.

 

[IOPort51]

Have you already gotten the replacement pans? are you going to make your own? I thought you removed the original pan by cutting spot welds and ended up removing the entire thing. then you spot weld back to the same place the originals welded to. Am I mistaken?? Do look for spot welds on the rocker. A spot weld cutter is like a drill that just cuts the outside of the hole so it leaves the weld itself, you can find one at Eastwood or a cheep one at horrible freight.

I am about to replace my front floor pans. I cant decide if i should butt weld or lap joint them. I wanted to get some of your opinions first. I am leaning towards butt welding them so you wont see them lapped from underneath and give a place for moisture to get in but i have read lapping them will be stronger.

Also, does anybody know how to remove the pan from the rocker. Is it put together with seam sealer or spot welded there? I only have a small place to patch on the rocker and dont want to bend it up while removing the pan. Any help is greatly appreciated.

 

[jb8376]

Yes I have the pans already. They are the key parts pans from quadratec that are stamped just like the original. I can not see any spot welds where it is attached to the rocker. It is smooth. I will sand on it some and see if a spot weld shows up.

 

[IOPort51]

If you can, look for them on the outside, they should be fair easy to see on that smooth panel with the right light. then you have a clue where to look on the inside.

Yes I have the pans already. They are the key parts pans from quadratec that are stamped just like the original. I can not see any spot welds where it is attached to the rocker. It is smooth. I will sand on it some and see if a spot weld shows up.

 

[jb8376]

Ok ill give it a shot thanks

 

[PaRenegade]

Everything is spot welded and sometimes they used seam sealer and other places they didn't. Do you not have any good metal left in the floor or is the seam itself bad? A lot of guys use the floor pans and cut them up some for patching rather than an entire replacement. Pics would help of your situation and I can give you some of mine to reference. I just spent the past year repairing my rusted out tub and I just spent the weekend seam sealing the whole bottom.
The body repair starts about here and goes for several pages.
30th Aniversary build- 82 CJ-7 Renegade frame off - Page 7 - JeepForum.com

As far as which joints to use. You may need some of each. A lap weld is always stronger and easier, but when fitting a piece in you may need a flush butt joint, which you could just weld that or put a scrap piece behind it for a backer. You'll find the old tubs metal, even when cut back to expose good metal, tends to blow thru fairly easy. Which ever way you choose I still recommend seam sealer on the outside and then some good primer and paint.
And, I don't know how much experience you have welding sheetmetal so in case you don't here's some advice. It's a game of connect the dots while avoiding the heat. Theres NO "laying" a bead like you'd do on thicker metal or clean metal. Once you get the dots fairly close (within a 1/2" or so) they will start to act as heat sinks and will allow you to do some short stitch welds. Your not going for pretty looking welds. A .025 wire with an argon mix works well.

 

[jb8376]

I have your build thread saved in my favorites and have been following it. You do some incredibly awesome work . My pan is rusted too the rocker. Not all the way through butt its pitted pretty good so I wanted to replace it. Ill end up using most of the pan except about the front 10 jnches or so from the firewall. I can post some pics when I get back home in the morning. I started cutting it out yesterday. I was thinking I would spot weld the rocker side and butt weld the other 3 sides. I just like the idea of it being a smooth seem.
Thanks for the reply.

 

[jb8376]

Here is some pics of before and after i cut it out. Sorry it took a while to get to it.

 

[PaRenegade]

I would plug / spot weld the side to the rocker. Drill your holes in the flange, then clamp it into place and mark the holes, then grind them clean. I'm a big fan of painting metal before welding things up, as you've probably seen. Even weld thru primer is better than nothing.
The only problems with flush butt welds is theres no adjustment once you cut them. So start with the rocker side since it's a fixed connection. Fit that side and clamp it tight in it's final position. Then, assuming the orig. body metal is cut back to good metal, mark the other sides and cut them to fit. If you do make a mistake or Murphy did something to mess things up, you can always use a sheetmetal backer if the joint gets too wide. And if no sheetmetal backer is needed for the joint, use a copper backer under it so you don't blow thru the metal so much. The weld won't stick to it.

 

[jb8376]

How do you hold the copper backer under the pan while your welding? Do you find a sheet of copper to use? Not sure where to buy copper like that. Thanks for your help

 

[PaRenegade]

You can buy short pieces of 3/4" copper pipe at hardware type stores. Get one and smash it flat. Then use magnets to hold it in place. You can buy ones already made from places like Eastwood but they're cheaper to make. I have a couple different pieces of copper, some with curves for odd shapes.

 

[jb8376]

That's exactly what I'm going to do. I really appreciate your help.

 

[jb8376]

What about painting behind a panel you won't be able to access after you weld it in place.
Do you use weld thru primer, por 15, ospho. Just want some opions before I weld it. I would hate to do all this work just to have it rust again.

 

[PaRenegade]

I started using weld thru primer but then figured a better solution would be Eastwood's Internal Frame paint, which I used a lot from then on. You just have to grind it away from any spot you'll be welding on. You can use POR but it's a hassle for small stuff and it much more toxic, but either one you should keep a fan going to blow the fumes away. Not directly at the weld because it will also blow away your shielding gas, but circulate the air around your head and hold yer breath while welding.

 

[jb8376]

I did see that frame paint on another forun and it looked like a good solution. I can't find any around here. I guess I will have to order some. I almost bought some weld thru primeruntil I read some reviews that it was not enough protection and some of the primers were not meant for mig welding. I found online copper weld thru that's supposed to be best for mig.