Welding floor pan gaps

[Fughuert]

I personally would not ever overlap panels but it’s fine if you don’t care how it looks and are gonna seam seal it.

You absolutely can weld these panels with flux core, it’s messier than a gas process and you shouldn’t overlap your tacks until you clean each prior one, I mean wire wheel each tack before welding over one.

Take your time, cool it down with a damp rag or compressed air if you’re getting impatient, don’t let it get too hot it will become a nightmare.

From all the boogers it looks like you’re too cold and trying to run a bead? Turn up a bit and sit in one spot make a nice tack, really let a puddle form then stop, jump a few inches down and repeat. Wire wheel em all at once then jump back and put another tack over the series of ones you just laid, repeat til solid.

I welded a patch in my rear taillight panel with stick, you can do this with flux core, keep watching YouTube videos. Other people have done it you can too.

Before & after

 

[Mikeythemikster]

Lol step away from the welder but seriously watch some youtube vids and learn how to setup the welder and learn the techniques then practice on some scrap pieces till it looks good and you have proper penetration

 

[someguysjeep]

I personally would not ever overlap panels but it’s fine if you don’t care how it looks and are gonna seam seal it.

You absolutely can weld these panels with flux core, it’s messier than a gas process and you shouldn’t overlap your tacks until you clean each prior one, I mean wire wheel each tack before welding over one.

Take your time, cool it down with a damp rag or compressed air if you’re getting impatient, don’t let it get too hot it will become a nightmare.

From all the boogers it looks like you’re too cold and trying to run a bead? Turn up a bit and sit in one spot make a nice tack, really let a puddle form then stop, jump a few inches down and repeat. Wire wheel em all at once then jump back and put another tack over the series of ones you just laid, repeat til solid.

I welded a patch in my rear taillight panel with stick, you can do this with flux core, keep watching YouTube videos. Other people have done it you can too.

Before & after
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.........you welded right to a huge overlap.

 

[TDI Sahara]

When welding a complex shape such as a floor pan why wouldn't you overlap seams? If you seam seal the edges no moisture can exist and therefore no rust can form. Cosmetically I doubt anybody would pickup on a detail like that especially if you took your time and did a good job.

 

[Fughuert]

.........you welded right to a huge overlap.

Where?

It was entirely a butt joint. The only spot that was a little easier was the body mount box acted as a backer plate for a small section, but I don't think I ever fused to it.

 

[someguysjeep]

that box carries all the way out and ends a couple inches past the body mount that's all a steel sandwich.
the steel box acted as a backing plate for you.

 

[Fughuert]

The box you're referring to isn't that big and isn't solid. Like I said there was maybe 3 of 7 inches on one side of the vertical butt joint I created, and like I said the panel doesn't get welded directly to it anyways. The entire top horizontal and most of the verticals were just a normal open back butt just like op is attempting.

 

[mrblaine]

I personally would not ever overlap panels but it’s fine if you don’t care how it looks and are gonna seam seal it.

Body work is going to be done on both, you did body work on yours, I did on mine. Why is overlapping incorrect if a flanger is used? The two surfaces that are seen are flush with each other without a height change between them.

 

[Fughuert]

Body work is going to be done on both, you did body work on yours, I did on mine. Why is overlapping incorrect if a flanger is used? The two surfaces that are seen are flush with each other without a height change between them.

It isn’t incorrect I just prefer to butt things up as it’s a little cleaner appearance wise. If a flanger is being used then you’re gonna get just as nice of a aesthetic from the top and it is easier to work with.

I prefer to avoid lap joints just due to working with old willys and how every panel is put together with flanges and spot welds and they all rust, even if the panel is clean the space between the flanges is rusting, of course modern seam sealers pretty much eliminate this issue but why introduce the problem just cause there’s a solution.

The main point of my post was just to help op along his learning process and ensure him he can do this task even though it’s turning out to be a big learning experience.

 

[mrblaine]

It isn’t incorrect I just prefer to butt things up as it’s a little cleaner appearance wise. If a flanger is being used then you’re gonna get just as nice of a aesthetic from the top and it is easier to work with.

I prefer to avoid lap joints just due to working with old willys and how every panel is put together with flanges and spot welds and they all rust, even if the panel is clean the space between the flanges is rusting, of course modern seam sealers pretty much eliminate this issue but why introduce the problem just cause there’s a solution.

The main point of my post was just to help op along his learning process and ensure him he can do this task even though it’s turning out to be a big learning experience.

Your TJ is put together the exact same way, spot welds and flanged joints. Where they rust isn't where the spot welds and flanges are. On the blue one, the rust started from the leaky right side where they all do but the rubber floor plug wears the paint away and since there is an edge, it just starts and grows across the floor. If you look, it crawled up the side and by all things water, it should have stayed in the bottom of the pan.

It isn't cleaner appearance wise. It is exactly the same if you want to full weld the edge and since it is not edge to edge with another piece of metal, much easier to weld.

 

[Stinkbug]

It isn't cleaner appearance wise. It is exactly the same if you want to full weld the edge and since it is not edge to edge with another piece of metal, much easier to weld.

This is 100% true. However, since it is hard to see in your original pictures, some might confuse a flange joint with a lap joint then it becomes the opposite of true.

On a side note: A good flanging tool saves a ton of frustration. I had a cheap hand tool that I tried before throwing it down the alley. I tried the harbor freight pneumatic one and I almost got it as far down the alley. I then discovered the Astro Pneumatic flang and hole punch tool. I would highly Astro 608PT for anyone considering a sizable project.

 

[Smtwnwygrl]

Ok so this is an update after I made the post and was waiting for responses. I tried to see if I could connect the big gaps and they kinda did . I grind them down a little to see if they burned through.

I looks as though It did. I also changed a little settings, like spoken in the threads.

I went to look for copper spoons and no one has them.

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concrete floor grinder
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A friend of mine has an old banger. Need the floor pand welding. Not the whole lot. For MOT purposes. Can I just lap weld on top from inside the car or must I lap join and weld from underneath. Just wondered if it mattered. - As long as its a weld all the way round I see no difference at all. I will waxoll the bottoms anyway. And take to a different garage. Your advice appreciated.

 

[PCO6]

A friend of mine has an old banger. Need the floor pand welding. Not the whole lot. For MOT purposes. Can I just lap weld on top from inside the car or must I lap join and weld from underneath. Just wondered if it mattered. - As long as its a weld all the way round I see no difference at all. I will waxoll the bottoms anyway. And take to a different garage. Your advice appreciated.

You can overlap the panels and weld the edge of each from the top and bottom sides BUT as I think you're finding out welding from underneath isn't always easy. You can weld the seam from the topside only and seam seal both the top and undersides but, the bigger the overlap the bigger the problem.

My suggestion would be to ...
- Cut and shape your new panel to fit.
- Assuming you're installing it from the top, lay it down and trace the outline with a sharpie
- Cut out the rusted area to allow for an overlap of about 3/4".
- Drill or punch holes of about 3/16" dia. in the new panel. When you lay it down on the old floor, you want to see the the original floor through the holes. These holes should be about 1" apart.
- With the new panel on top of the old, use rosette or "plug" welds to attach the 2 panels. A rosette weld is similar to a spot weld. With a MIG welder, you want to fill the hole with welding wire to attach the top panel to the bottom panel. Aim the MIG wire at the centre of the hole, tap your trigger and fill the hole with weld. Each weld should only take about 1 second.
- Make your first rosette weld, skip 3 or 4 holes and make the next weld. Keep going around the panel and eventually fill in the holes between the 3 or 4 rosettes.
- You're probably going to have to hammer the 2 sheets of metal in various areas to bring them together for the welds.
- Apply seam sealer to the top and bottom sides when done.

I've done many floors like this and for the most part it avoids welding from the bottom side or from anywhere where you don't have access to weld from the back side.

You can drill the holes but a pneumatic flange & punch tool will save you a lot of time. Here is the one I use. Punching holes is quick, accurate and saves a lot of drill time. Flanging the metal isn't necessary for what I described above but I've used it for attaching other panels. It works great and adds strength to the panels.

Good luck!

 

[PCO6]

If you really want to speed things up ... find yourself one of these! This welder will lay down 2 spot welds with one trigger pull. It's meant for sheet metal but I've actually welded 18g sheet metal to 1/8" steel tube with it ... and it's quick!

 

[Moglocker]

Body work is going to be done on both, you did body work on yours, I did on mine. Why is overlapping incorrect if a flanger is used? The two surfaces that are seen are flush with each other without a height change between them.

Yep,we go over ours with all metal,at our shop.

 

[AirborneTexasRanger]

If you really want to speed things up ... find yourself one of these! This welder will lay down 2 spot welds with one trigger pull. It's meant for sheet metal but I've actually welded 18g sheet metal to 1/8" steel tube with it ... and it's quick!

View attachment 385871

View attachment 385872

Is that a spot welder?

 

[PCO6]

Is that a spot welder?

Yes, it's a Porta-Spot that's about 50 yrs. old. They were popular in body shops for overlaying patch panels on fenders, rocker panels, etc. I've used it for all kinds of fabrication jobs though.

You basically put the 2 copper prods against the top sheet of metal about 1 to 3 inches apart and push the button on one of the prods. It results on 2 spot welds at a time.

 

[Hazegray]

Quality Flux core wire is your best friend here. If you are using the flux core wire, i.e. Lincoln, from the big box stores it has a bad reputation for excessive spatter. Do a search and you will see.

Also, every time you stop welding with flux core, run out the wire about 1-2" and break it off. This will ensure you have fresh flux every time you start welding again.

 

[PCO6]

Quality Flux core wire is your best friend here. If you are using the flux core wire, i.e. Lincoln, from the big box stores it has a bad reputation for excessive spatter. Do a search and you will see.

Also, every time you stop welding with flux core, run out the wire about 1-2" and break it off. This will ensure you have fresh flux every time you start welding again.

Flux core YES ... coat hangers ... NO.

A loonng time ago my Dad was teaching me the basics of O/A welding. We did a small floor board patch job on a customer's car as a bit of a favour. He was out of steel welding rod so he grabbed a coat hanger. His first words of advice were ... "don't ever do this and if you do don't tell anyone". They're apparently made of low grade metal and coated to keep rust down. I don't honestly know because I took his advice and that was the last time I used one.

 

[Mike_H]

Flux core YES ... coat hangers ... NO.

A loonng time ago my Dad was teaching me the basics of O/A welding. We did a small floor board patch job on a customer's car as a bit of a favour. He was out of steel welding rod so he grabbed a coat hanger. His first words of advice were ... "don't ever do this and if you do don't tell anyone". They're apparently made of low grade metal and coated to keep rust down. I don't honestly know because I took his advice and that was the last time I used one.

LOL. I had a buddy in college that showed me how to Gas weld. We used coat hangers and scrap steel to practice with. Coat hangers have a special place in the garage with duct tape and WD-40. I use them ALL the time for various utilitarian purposes. Paint hooks, caliper hangers, tape a magnet to the end and you can reach that bolt or wrench you dropped...