I am mini tubbing my 1967 Plymouth and have cut the old wheelhouses out and the additional 3 inches to the frame rail. I'm not super excited about cutting the flange on the frame rail. Looks to me that that is compromising the strength in that area. I attempted to weld the floor pan to the frame rail to possibly add some strength back into the area. Welding did not go well as the metal burns away very easily. Should I be welding those back together or am I over thinking it. Any suggestions/techniques or ideas would be greatly appreciated.
Welding tips or suggestions
- Thread starter Green72
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ckessel
Well-Known Member
I did that on my 65. On welding the floor to the rail, I set the unit for 16ga I think. 14 might be too hot. Concentrate the weld more on the rail edge and not the floor since the floor is thinner. Don't try to make one long weld. Make many short welds. Weld, stop till you lose the glow, repeat. Might help to give yourself an inch or so in between to help control some of the heat. Welding thin stuff on its edges can be a challenge. Take your time.
Is wire size a factor? I'm running .030 solid. any advantage to flux core?
Runcharger
Well-Known Member
If you cut the flange off, I would add one on the inner edge. Solid core is the way to go with gas, you should be able to make 30 work but a roll of .023 would work better. Practice on scrap if you can.
vance.dykes
Well-Known Member
read the mopar chassis book on super stock suspension just support the rear hafe so it dose not bend i used 4x4 to hold just before cut with plasma cut the frame rails
So you've cut off the flange and now you want to weld the edges together. That's a tough go even for a good welder - you probably have large gaps.
I would bend up some 90 degree flanges out of 18ga and plug weld those to the floor and frame rails and call it a day!
I would bend up some 90 degree flanges out of 18ga and plug weld those to the floor and frame rails and call it a day!
j-c-c-62
Well-Known Member
Yes, .023 is a better choice, slow down, drop your amperage as needed, welding thin is always taxing, make sure your MIG set-up is on correct polarity, keep weld area as clean/shiny as possible, your flange removal concern is valid, I distaste flux core, best is, again IMO 80/20 Argon CO2 mix, by the time you get to the other wheel you will have this figured out. 
Huh ??? I don't think his plan is to remove any of the frame rails. He's just lopping off the flange so the tub will fit flat against the rail.
vance.dykes
Well-Known Member
if you do not move the leaf spring inward what are you gaining ?
i am going inboard with springs. but that is not what i was asking about. but i will take a look at the mopar chassis book when the time comes
that is an option that i have considered. it will have an affect on how the tubs land against the frame rail
If a 67 rail is the same as a 64? No need to cut all the flange off. The rail flares out and is wider at the top than the bottom. So you only need to trim the top edge of the flange. My 64 has thin aftermarket full tubs. So they provide no strength like a stock wheelhouse. Even so, with the flanges trimmed the quarters are arrow straight after 12 years and 1100 passes. This car wheelies every pass and runs 1.2 60ft times. I say cut it. The rail does have a large radius near the floor. So leave a 1/8" or so of the rail radius sticking out. There will be one small triangle area that will need a filler piece. Easy to weld with .023". Just take your time. The plate with the tube is the upper shock mount.
Doug
Doug
j-c-c-62
Well-Known Member
The u-shaped rear pair of humped sheet metal frame rails have a small 3/4" outward flange on the top of each vertical leg turning outwards. The outer flange must be removed in order to gain all allowable width for the relocated wheel housing that is moving 3"?
sam dupont
Well-Known Member
be mindful that if you make a long weld, the metal warms up, effectively changing the heat setting.
Not worth worrying about !!
Keep in mind the inner wheelhouse just gets moved over to the rail - it fits to the rail as if the flange were still there - in other words it still hangs down about an inch all the way around so it covers those gaps. The attached shows where the tub should meet the rail (I didn't go all the way to the rail on mine) Those lines were made holding a square on the frame rail to the bottom lip of the tub before it was cut off.
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WS23U1
Well-Known Member
Don't practice welding on your car. Get some junk metal and keep at it till you got it. Sometimes local colleges or schools will have a class or two you can take. But if you are just not that good at it just tack it up and have someone come to your place to finish it up or haul it to a local welding shop and have them finish it for you. There's nothing like learning but welding does have some science behind it.
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When welding thin metal you can use a backer like a piece of copper or brass behind the weld to help with blow through. 1/2" thick or better. I'll even smear a little nozzle dip on the backer to help keep it clean.
ckessel
Well-Known Member
On my 65, along with the mini tubs, I moved the springs in. Used the USCT stuff for both. I cut/ground the rail flanges flush where needed for the tubs. The floor did pop up in some areas due to losing the spot welded to the rail areas. On the popped up areas, I pulled the floor down to the rails with C-Clamps, did some tack welds, move the clamps, repeat until I didn't need the clamps. From there, did many short welds to get the two portions attached to each other. Once the tubs got fitted and welded to the rails, I bent some 90* pieces to weld between the tub and trunk floor area, in the trunk area, to give some additional attachment from the floor to the tubs. Plug welded them too. My Mig is a Lincoln Power Mig 215. I used .030 solid wire with the 80/20 Argon/CO2 mix. As mentioned above, practice some on some scrap. The rail material, 14ga I think on mine, isn't bad to weld. The fun stuff is the floor. Its 20ga.
Thanks everyone for the great information!! Always learn from this site.
So what I ended up doing was cutting a section of floor to gain access to the inside of the frame rail. I then bent up some sheet metal to follow the top edge of the frame rail. Basically, I created a new flange on the inside of the rail. Then plug welded the frame rail and the floor to the new flange. I'm really happy with the results and think I have negated any loss of strength.
So basically, I'm saying I came here for advice then just did it my way anyway LOL
So what I ended up doing was cutting a section of floor to gain access to the inside of the frame rail. I then bent up some sheet metal to follow the top edge of the frame rail. Basically, I created a new flange on the inside of the rail. Then plug welded the frame rail and the floor to the new flange. I'm really happy with the results and think I have negated any loss of strength.
So basically, I'm saying I came here for advice then just did it my way anyway LOL
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