I am to the point of repairing my cab corners and have been trying to get the courage to cut and weld on the cab. I have been researching and studying for a while now but.... I have the cab off the frame and stripped of everything including doors. Thought that would be easier with better access but now I think I should mount the cab on the frame and install the doors to check fit before I cut weld the new corners. It is making me nervous not being able to be sure of proper fit and finish and I am really afraid of warping what is otherwise a very straight cab. I also need to replace some sheetmetal on the front part of the rocker from the front doorjam to just past the lapped seam. I have not quite figured out the reason for the sheet coming from behind the front lower cowl lapping the rocker. Is this part of the triangular brace in the kickpanel area? How have you repaired this? Sorry for the long post...just trying to get a little motivation and experienced advise from someone who has been there, done that. Thanks in advance....Kevin

 

Yes, having the nearby panels installed is never a bad idea. In this case, the doors in place will give you peace of mind the gaps will be correct when the corners are installed.

 

It can't hurt to have the doors mounted, but if the door frames aren't sturdy enough to hold their shape while the corner is cut out, I think you've got more to do than corners! The rockers should keep everything tied together.

 

Kevin, I did quite a bit of reasearch before cutting the corners of my 51 cab. I just had some small areas of rust one about the size of a dollar bill. I didn't cut the whole corner section out just did spot repairs. Some of the guys said to just cut beyond the rusted metal just enough to get to the good metal. That's what I did, probably a good thing, as I have a lot of experience with a Heliarc, but the Mig on that thin sheet metal was a whole new experience. I need more experience and a better Mig unit before I tackle that door seam. One guy posed the question how long do I want the truck to last. I have never kept any vehicle over 8 years. So I feel that those repairs will last as long as I own it. My 7 year old grandson announced he wants the truck when I'm gone. So he will probably get the corner installing experience.

Rod

 

Rod

That brings up a good point. I always patch rather than install a patch panel if I can. It's a rare day when a patch panel fits near as well as stock. Provided you have sound metal to deal with of coarse.

 

Bondo the whole thing! Just kidding. Remember during the tacking in any patch panels or any thin metal just take your time and go slow. Allowing enough time for the metal to cool on its own during short welds should prevent any warpage.

 

Warpage wasn't my problem it was burn through. I tried the tacking and I'm getting better. I finally put pieces of sheet behind the gap and that helped control the burn through.

 

Try a wet towel behind the sheet metal where you are welding. It worked well on some 24 gage that I was trying to weld. Unfortunately, other problems like my inability to see properly caused weld beads nowhere near the metal seam.

 

Dewayne,

How to you generally shape the patch panels you make? I have had some luck using a ball-peen hammer (both the flat and round ends) and the cut-off round bottom of an old gas cylinder (OK, laughing is allowed now ).

As is Kevin, I'm headed into cab repair in a big way soon. Should I be looking at some body hammers and dolleys? Lead shot in a canvas bag? A good book on how to do body work? A class in body work at the local vocational school? A degree in cosmetic surgery? A patience training class? A good psychiatrist? All of the above?

I think I have the patience to work the patch panels so they fit just right. If that is the secret before welding them in, I think I will be OK.

One other thing. My cab may not have the rigidity to hold it's shape as well as I'd like when I cut out the corners. I don't know if Kevin has to cut out as much as I do. Should we be considering interior bracing (like 1x1 square tubing) installed with the doors in place? I'd like to remove the doors during the actual cab body work so I can put the cab on some sort of rotisserie. That would allow me to get at the front and back corners as well as the floor.

 

"I think I have the patience to work the patch panels so they fit just right. If that is the secret before welding them in, I think I will be OK.

George

That is absolutely the secret. I like near zero gap seams. A small gap is textbook, but the MIG will weld all the way through on metal this GA without leaving any gap. Patience and a variety of cutting and trimming tools are what you need. You don't have to spend a fortune, but a pair of tin snips and a 7" grinder don't get it. I use my cheapo air cutoff wheel constantly. And don't try to weld to tinfoil thin metal. You have to keep cutting until you hit good steel, or you are spinning your wheels.

As far as making patches, I wing it using whatever looks like it would make a good dolly. Depends on the shape I want. I own a small sheet metal brake. But a couple pieces of flat stock, scrap lumber and clamps worked just fine before I had any tools. I've never had a panel beater bag, but they look handy.

You better brace if your cab is going to squirm, or you'll have a mess.
And I hear you on entirely missing the seam with the weld. It happens. And it's such a happy feeling until you lift your helmet because you know the weld isn't burning through.

 

When it's time to weld my cab corners, I'm going to practice with same gauge sheet metal until I've got it figured out.

I've heard that using copper to back up the weld works well. I've also heard that you've got to get the gap as small as you can; smaller than the size of with wire you're welding with. Stitch the panel into place. If you're using flux-core, it leaves lots of smoke on the steel so you'll have to sand the metal clean between weld sessions.

I'm going to convert my little welder to MIG before I start to weld the cab.

 

i have just been through it with a 56, someone had already hacked the originals off and welded in patches from another cab, so we could'nt just replace the original rusted bit, the repair sections r better than rust but not as good as henry made, the swage lines aren't sharp enough but the general shape is ok, once u cut out the bad section, square up your cuts then make your patch that size using a scribe and patience, tack it in then have a look, the door gap in this area on it's own should not be a problem because it is only a minor portion of that opening, i found that a #6 oxy tip fused it just right and left a weld u could work with, with the mig u have to grind too much, if your cut isn't perfect, a peice of copper held behind can help in two ways, it will let u fill the gap without much material building inside and also soak up some of the heat, but u must continually cool down the copper block.
now in hindsight, i spend a good thou more when buying a cab so repairs r kept to a minimun, it still costs about the same but with less stress.
cya..gary

 

I replaced all four corners on my 53 last spring. I used a mig gun. I found that every one of my corners required a bit of tweeking be for installing. I cut the old cab corners out with a grinder. cut the openings smaller than the
new panels then fit the new panels and CAREFULLY cut them to fit my cut outs. I then stiched them in using a mig gun. Take your time. fit carefully
weld small sections and allow time for cooling. I had never used a mig gun
before starting this project. I did take a course at a local trade school and practiced a good bit before starting. I think I ended up with a good job. the key word in all this is patience. Good Luck Don

 

You'll need some sort of resilient surface like a shot bag and a good sized nylon raising hammer (head like a fat teardrop) if you are going to be making compound curved patches. A pair of homemade or purchased fluting pliers will make edge shrinking a little easier. A real secret to making sheet metal shapes other than flat or single curved/bent panels is using aluminum killed sheet metal. A little more expensive and hard to find than cold or hot rolled mild steel but VERY easy to work with, like working aluminum, yet plently strong when shaped and easy to weld. Ron Covell sells the AK sheet on his website, you won't need a huge amount, and the ease of working will make it well worth it. 1/8" copper backing will make you welding life a lot more pleasant, just be sure it is tight against the back at the weld point. The weld wil not stick to the copper.
I would also suggest buying Ron C.'s video or DVD on metal forming if you don't know the difference between raising, boughing, shrinking, on-dolly and off-dolly work. Truely seeing it done by a master is SO much more informative than any book or written description. If you have a chance to take one of Ron C.'s or Ron Fournier's workshops run don't walk to sign up, it's the equivilent of years of on your own experimenting and practice.
Esab's "easy grind" MIG wire will also make finishing the welds a lot easier both for grinding down and stretching back out the inevitable shrinkage along the weld seam.

 

On my F600 I had to put the front cab corners in on both sides. This was my first attempt at body repair. I discussed this with the body shop that was going to end up painting the truck. They suggested I OVER LAP the new panel. Thats what I did. I fully welded in the panel, Plug welded in the jam area (drill holes in the new panel and mig the hole closed to the old panels) The body shop said that I did an excellent job and I too made sure fit was ok before welding.

Just a note I had no problem with burn thru and I think its because I overlapped the pannels. A little grinding and a little mud and it looked great!

Kevin Bigwin