Bed Seam question (more of a welding question)

[stang1986gt]

The previous owner of my 69 really screwed up the bed sides of my truck. He replaced the front and back halves on each side, but instead of welding them to the upper panel from the back/underneath, he put several crappy spot welds in the seam to hold them on and the bondoed 80% of the bed (no joke). I've already removed all of the bondo from the body (he even cut the front and back of the new panels off and layed them over the original sheet metal (no, he didn't even flange them so they'd fit flush) so he wouldn't have to remove the bed) and I'm ready to weld it right. Tell me your thoughts on my plan:

I'm not going to smooth the body line because it's only going to be a daily driver and I kind of like the factory look. Should I put some metal screws through the new panels underneath to the bed cap to pull the panel flush, and then remove the screws one by one and plug weld from the top (I'm thinking this because I'm not sure if I can weld upside down...meaning, I don't know if I can get under the bed to spot weld the new panels to the bottom of the bed cap panel and do it correctly. Can this be done, or should I do the screw method? I'm not wild about doing that, but as I don't have the room or the help to remove the bed and position it so I can spot weld from underneath, I'm not sure how else to do it unless someone can tell me whether I can weld it from underneath...make sense?

[fordman]

welding upside down isn't that hard to do. you just have to watch what your doing. if you are not that sure about doing it. then do some practice welding on some scrap pieces upside down.

[stang1986gt]

I would imagine you'd have to just go a little slower. Let me ask this also...do I need to increase or decrease the heat? What about wire speed...increase or decrease?

[fordman]

i'm not very experienced with wire welding. i can stick weld. the only wire welding body panels i've done burned through the panels and i filled them with more welding. it was just for the experience that i did it. i have yet to grind it off to see how good i can get it to look yet. but its only a pickup bed trailer so it doesn't matter.

[FORDification]

Welding thin body panels with a MIG is tricky....I've only tried it a few times, and have had problems burning through the metal. However, I've got a 175-amp Hobart, which is probably a little bigger than what you'd want to use. However, the last time I was messing with it I found that I could achieve decent results by turning the wire speed and amp settings down as far as they'd go. Even then, I still have to keep it the gun moving at a fairly brisk pace.

I'm getting ready to do almost the exact same thing you're facing. I have to replace both lower bedsides (below the seams), but the interesting part is the only decent donor truck I have with good bedsides is a LWB, so I'm going to have to cut them down to fit. However, I am going to fill the body seam, since it'll be a lot easier to attach the bedsides to the upper section by simply filling in that seam.

It's kind of hard to visualize what you're having to deal with. Can you post a couple pictures to show us the damage?

[hutch1973]

I learned to weld in a commerical hvac shop, where everything you do is light gauges. I have gone as light as 24 gauge and gotten it halfway decent. The only thing that works, as above mentioned, is lowest voltage and wire settings, and keep the thing moving.

If you get really good at it and want to make a buck, I just had a guy up the street ask if I'd weld up his truck bed for him. He has a short box that he rolled last year offroading. He found a donor body LWB and cut the front foot or whatever off the bed so it would fit. Now he's looking for someone to weld the front back into it. He has been running it for months with a heavy gauge wire holding the sides together.

[stang1986gt]

Welding thin body panels with a MIG is tricky....I've only tried it a few times, and have had problems burning through the metal. However, I've got a 175-amp Hobart, which is probably a little bigger than what you'd want to use. However, the last time I was messing with it I found that I could achieve decent results by turning the wire speed and amp settings down as far as they'd go. Even then, I still have to keep it the gun moving at a fairly brisk pace.

I'm getting ready to do almost the exact same thing you're facing. I have to replace both lower bedsides (below the seams), but the interesting part is the only decent donor truck I have with good bedsides is a LWB, so I'm going to have to cut them down to fit. However, I am going to fill the body seam, since it'll be a lot easier to attach the bedsides to the upper section by simply filling in that seam.

It's kind of hard to visualize what you're having to deal with. Can you post a couple pictures to show us the damage?

Yes, I'll get some pics as soon as I can. In fact, I may document what I'm doing and how it turns out (good or bad) so that others can learn from my mistakes and perhaps give some advice on what can be done different, if that's ok. My bed is covered in surface rust, so I'll remove that before I take pics.

Also, I found a REALLY good message board yesterday about MIG welding and inverted welding. The link is at work, but I'll post it when I get back there on Monday. I learned a lot about inverted welding, and MIG welding in general. However, with welding as with many things, you can read until your eyes fall out but you can only learn and get better by getting in there and simply doing it.

Thanks for everyone's advice! I'll post pics and the link soon. (Gotta get ready for my boy's birthday party...he's 2 today! WOO HOO!)

[fordman]

i had my heat as low as it would go but i had the wire speed too slow so i was sitting in one place too long waiting on wire.