floorpans on 75 911

[kz1911]

i have cut out the original pans and have purchased the new ones, rust proofed with por 15 and ready to put in, i cut about 1 inch on the periphery to get rid of the accumulated rust and was curious what i can do to make the new pans sit flush as they should just like the originals.
maybe use a strip around the periphery to add to the lost 1" of metal?? was thinking of tacking it first by putting metal strips around every 6" then putting sheet metal between the pan and the frame

any advice would help

[Porboynz]

Well you can butt weld the strips in and with a lot of filing/grinding get it real smooth again but is it worth it? If you do overlap the metal by 2-3mm then you can MIG both sides if you are keen enough. You will need to move from section to section to allow for cooling off to avoid pulling and distortion. This way you can still grind flat and have the strength of an overlapped join. Try each method with scrap sheet steel and see what gives you a finish you are happy with, and best of luck, your MIG welding skills will be tops by the time you are finished.

[kz1911]

thanks I will try it today, my buddy is a welder, he works at a welding co. and we are going to use a stick welder, im not a pro at this so i will have him do the welding while i prep the spots, i was thinking the same...spot weld every few inches with periods of breaks so it cools off or just hop around the periphery, i want to leave the little gap because i cut off about 1" of material all way around and dont want floor to be pushed up by an inch, trying to keep it as original as possible

[mcaterino]

So to be clear, you cut off the entire 90 degree flange all the way around the new pans, plus a little bit of the flat part? If that is so, I'm not sure simply filling in the gaps is the way to go. Can you post some pictures of your floors and of the undersides of your rockers? The flanges of the floors are supposed to butt up against vertical flanges of the rocker panels, and the two are spot or plug welded together. I believe that this two layer vertical joint imparts a fair bit of structural rigidity to the chassis that would be lost if you simply welded the floor flat to the rockers.

What kind of shape are your rockers in? It sounds to me like there's more work that may need to be done there. And then I'm not sure that it wouldn't be worth getting complete floors and doing it right. But more than anything we should see what you're actually dealing with.

Mike

[kz1911]

yes the rockers are in good condition, the reason for the project was b/c the floor centers and flat part were badly rusted with holes in them, very brittle, i noticed that the rockers and the pans do meet at a certain point but i might cut out a small portion of rocker to fit it right, refer to pics for guidance, i also plan on afterwards putting thin steel bars across and flush with the floor to strngthen the chassis as well, where i am pointing in the pic there has been about 1" cut off, my concern was to not have the floor pans too high up if you know what i mean....i lost an inch of space there

[kz1911]

MC, sorry that last message didnt clear it up, heres a pic of my new pans which were unmolested, i simply rust proofed only,

[mcaterino]

Got ya! I see what you're talking about. You just had to trim off the bottom edge of the tunnel. Not so bad. It's still going to be a tough job. That edge should end in a horizontal flange that sits on the surface of the pan, also spot welded to the floor. That's probably not so essential there, as long as they meet. There is a 'step' near the middle where the front half of the pan sits higher than the rear. That may be difficult to replicate. You can see what it should look like in the picture below.



Here I hadn't yet trimmed the pans across the middle where the reproductions overlap too much. I was just getting everything aligned. That's what your next step will have to be, to clamp the pans along the sides, press them up gently in the middle to get them near where they should be without buckling them upward too much where you're missing metal, and then measure the width of strips it will take to fill the gap. Actually, you might try making long 'L'-shaped strips that can sit on the pan, like 1cm along the floor edge, 2-3cm vertical, then tack it to the side of the tunnel once the pan is pushed up and aligned. Then you can pull the pan off, weld the flange strip to the tunnel, and the alignment should be right on.

Big job. I kind of miss that work, though. Good luck!

Mike

[kz1911]

i was doing the stick welding on it and noticed it is not good, they kept break on me, what is the best way to get these pans welded on there? mig, tig or stick? i had purchased a little 70amp stick welder and tried it out but im not happy with it after a few tacks broke off, am i doing something wrong??

[kz1911]

MC that is exactly like my situation except my tunnel and periphery doesnt have that flush look as i had to cut out about an inch off, so i have to basically use the little L steel pieces to tack it on

[mcaterino]

i was doing the stick welding on it and noticed it is not good, they kept break on me, what is the best way to get these pans welded on there? mig, tig or stick? i had purchased a little 70amp stick welder and tried it out but im not happy with it after a few tacks broke off, am i doing something wrong??

Can't help you too much there except to say that I learned welding with a MIG, on this project, and it did the job for me. Lots of folks seem to prefer TIG. Maybe some will weigh in.

Mike

[Jagshund]

Run a 6' level across the bottom of the longitudinals and add the missing metal back to the tunnel. Not sure what you mean by cutting rockers to allow fit?

Might want to consider grinding the POR15 off the areas near/under flanges prior to final fit or you'll end up with contaminated welds.

[afterburn 549]

Please do not use stick welding........too much heat........if you can do it

[kz1911]

afterburn, cayman and MC you guys are right, I came to conclusion that stick weld is not meant for this job, my buddy who works as welder and does mostly aluminum welds and mig said same thing, the welds were not holding on and at high amps risked burning holes in pans. i will get a mig welder online and have it done soon, the job itself isnt as bad
Cayman...I am going to use little "L" shaped steel pieces/brackets to hold the pans in place every 3-4" perhaps, i wanted to see what other peeople would do in this situation and that's good to know, all your advice has been great, thank you guys

[Porboynz]

Make sure you get a MIG with Argoshield gas. Gasless MIG welding with coated wire is one step up from arc welding IMO, not good enough. A good MIG with Argoshield gas is almost impossible to stuff up when welding on the flat and can also be used to make fairly good spot weld look alikes with practice. Make sure the metal is shiny clean, you can not weld rust or POR15.

[Porboynz]

Looking at the photos I would get a sheet metal shop to fold up some lengths of 1mm sheet steel with about a 10mm L section at the bottom of the L to spot weld to your new pan. You can then straighten up the cuts you have made and tack the new folded steel to what remains of the tunnel etc. Its mainly straight except near the front. I would not bother with a butt weld, a few mm overlap will make a stronger join. I suspect this is not intended to be a concours show poney so you can rebuild her stronger with an overlap.

[kz1911]

Yes you're correct, I bought some L shaped steel which is fairly thick and strong which i will use, it is the same materials they make shelves for and has holes along it, it is perfect because i can weld through the holes as well, i mean this stuff is strong, as a final touch i will use sheet metal to seal/close the gaps and yes i have been removing the POR 15 in the weld spots, I will be heading out monday and check for a MIG welder but am not sure if gas one is as affordable or reasonable, will this be a problem if i use gasless MIG?

[safe]

Buy a used mig WITH gas of a well known brand and good quality. They are usually easier to weld with and easier to sell on if your done with it.

[kz1911]

Ok I think i'll look around for a mig with gas but my concern is....is it a big difference in quality of welds when using MIG gas vs gasless??? am I going to have a harder time if i use gasless or will the welds inferior if i use gasless? I just dont need all this equipment after I do the job that's all.

[Porboynz]

Its the old story, good tools can help an amateur produce good results, bad tools will not stop a craftsman producing a great result. Get the gas version, its just so much easier to produce a great result. I once had a qualified welder come around and use my old stick arc welder to repair a trailor chassis. He welded this beautiful bead both upwards and overhead, the flux just peeled off like a scorpions tail. It was beautiful to watch. He told me welder was a bit tricky to use as it only had two heat settings but he still did a great job, way better than I ever laid a weld using it. When I got my gas MIG I was able to lay great welds with very little practice, its just worth the extra.

[kz1911]

that sounds good, i'll check out what they have and how much they go for, i dont want to dish out $300 or more on something i wont be needing afterwards, stick welds are very tricky if you dont know how long to hold it in a position and it will burn a hole in the metal