The aftermarket parts are notorious for not fitting well. They are thinner also. If you can repair the original doors with patch panels you would be better off.

A guy I work with had a 94 f350 he bought used from a dealer. He had it for years, and was complaining to me the pull where it he shut the door had come loose. He took the door panel off and found the metal of the door was cracked. Complaining about it, I asked him what color the metal was. He said it was black. The original door would have been blue like the outside of the truck. I told him that door had been replaced with one from China, and that was probably the reason it cracked. They make them too thin.

 

I and others have found the Tabco patch panels to be pretty good and thicker than most others.
All mine were Tabco patches.
Dave. ----

 

Alright so after reading everyone's posts I switched the game plan up a bit. I'll do the floor first, then rocker/cab back corner/pillars, then finally the cab mount. I cleaned the area best I could, then laid the entire floor pan in the cab. I marked around the edge to get an idea of its coverage. Then, I cut a hole that was about 1" smaller than the mark.






There were some spot welds I had to drill out. The harbor freight spot weld cutter broke on me after removing two...



I was able to put the pan in and get under the truck to mark where the opening was. I then made another mark about 0.5" bigger than that so I could slowly move to making the pan smaller.



Here are some shots of the hole and the cab mount.







I trimmed the floor pan a little bit but need to do more so I can butt weld it together.


I bought a sheet metal tool for cutting because cutting and grinding using an angle grinder was taking forever. Next thing on the list is to continue making the floor pan a smaller size so I can clamp it and butt weld together.

 

Butt welding makes a nice job that is pretty much undetectable, but it can be very difficult and time consuming to do. I usually just leave that 1/2 inch and just punch holes in the patch panel and then spot weld it to the old floor. Then slap sealer over it top and bottom. That's all the factory ever did when they put the truck together.

If you want a trick on getting the panel butt welded, here's a link on how to do it.

 

X2 I was not doing a trailer queen truck so I over lapped the floor pans and also punched holes around the outside to plug weld through.
In fitting the floor before cutting I needed to bend it to fit better and before welding in had to use weights to push the pan down as I did not have a helped at the time.

Starting here 1980 Ford F100 I have pictures of how I did mine that might help.
Doing a good job keep it up
Dave ----

 

I used self drilling screws around the edge where I needed to, so the repair patch would be pulled tight against the truck floor to weld it. I then removed the screws and welded the holes shut. Nothing critical here, like I said that whole screw hole/weld area is sealed with body sealer.

 

I also sealed both sides of the over lap with body sealer 2 time to make sure it was sealed and did 2 coats of roll on bed liner.
Oh I also sprayed the welding lips with weld through primer before I started welding it looks like white paint.

Here it is with seam sealer

Bed liner

Dave ----

 

Alright so I got the floor pan cut to almost the right size and put some tack welds in. Some sides had good, small gaps where the weld was easy to get on. In some other places, the gap was over 1/4 inch. I needed to cut small pieces to help fill those...




So after a million tack welds I had a pretty complete weld line and it felt decently strong. Much better than before obviously.


Since I did such a hack job I had to grind a ton of metal off. But, I was able to get it somewhat smooth. There were still pinholes in some spots where the gaps were large. Just to be extra safe, I'm going to do some welding on the underside of the cab so I'm sure the weld is strong. I have to flip the cab over to do some repair of the braces down there anyways.




Admittedly, there were holes that would open up due to the heat of the MIG welder and I just couldn't close them up with my technique. So I did have to resort to this weird lap weld in an area or two. I'll need to live with it and cover everything well with seam sealer later.


So with that mostly done for now I moved on to the cab corner. First I put the door back. It was not latching properly when I took it off to begin with, so I messed with the adjuster bolts to line it up the best I could. Not perfect still but close enough for me.


With the door moderately lined up, I begin taking measurements and started cutting the cab corner off for replacement.




So the cab corner, rocker, and pillar all need to be replaced. I have these parts already, but the question is how do I move forward? Do I cut out the cab corner, pillar, and rocker and fabricate it all once? Or do I cut out cab corner and weld in the new one first, then move on to the others one by one?

 

Dave F - thanks for the video tips. I did use an angle grinder cut-off wheel to create the gap on one of the sides. The gap was still pretty big... I think next time I will take waaaay more time prepping and making sure that there is almost zero gap so that the weld is nice and clean.

Dave G - I've looked through all the pics you have posted... good motivation. I'll be trying to follow your procedure as best I can.

It's been fun learning how to butt weld, but I see why you both did lap welds. It takes so much time. I'm getting better though.

 

Do you have the full official rocker or just a rocker cover? If you have the full official rocker I think I would install that first.

 

Yea if you go back over my pictures you might be able to tell how I did it as I dont remember right now.
Looking over the pictures it looks like I fitted everything including the floor before I welded anything.
1980 Ford F100
If you click on the picture(s) they get larger so you can see more details.

Now I did not have the doors installed like you so if the opening was too small or large I would not know till the doors went back on, read too late.
If the doors were on I could have measured the opening and adjust it before clamping the rocker in place.
I was pretty lucky it was not off much.

You are doing a great job and you see why I did over lap welds
Dave ----

 

I'm pretty sure I have the actual rocker... it matches what I want to replace. So yeah, I took your advice and started to remove it. I figured I might as well remove the pillars while I'm at it, so I took out most everything that had major rust. There's still some on the main floor of the cab. I'll be cutting that out soon.






Sounds good. I'm basically doing the same thing as you... trying to replace every part that's available because everything was rusted. What should I do after I grind down the welds to be smooth? I read somewhere bondo, then sand, then a rust sealer, then seam sealer.

I took the door back off so I could make these cuts, just wanted to make sure it fit right and do some measurements. I think that I'll fit everything first before I weld like you did, put the door back on if I can, and if it works then start welding. Thanks, nothing went super wrong yet! Hopefully it holds up. Seems pretty sturdy.

Next thing after removing the rusted parts was I noticed the metal near the front pillar was warped and rusted. So I cut it out and welded a new one in. I needed a good piece so that the sill/rocker can be welded to it. Have to weld one more metal piece in that I cut off during the pillar removal, then I can move on to the back pillar area.

 

Alright here's another 20-30 hours of work on this cab repair. I fitted the pre-made sheet metal as best I could and held them in place with clamps. Some of the rusted metal on the driver side didn't have pre-made parts, like the metal under the cab corner and the outer edge of the cab. So I had to make the shapes with flat sheet metal and basically no metalworking tools... not perfect but they'll do the job I think.

I'm slowly getting better at welding. The first pieces I put in required a lot of rework, but the last piece I was able to get in without a ton of grinding. The hardest part is welding to weakened, rusted metal... hard not to get blow through with the welder. Luckily i've been able to replace basically all the rusted areas.

Everything seems solid and strong, and I only see a few extremely tiny pinholes when I shine light through the bottom. I plan to use a ton of epoxy primer, seam sealer, and maybe some metal filler to make sure the welds stay tight.

I've got to weld in the cab corner and then I'm moving on to the passenger side.

 

The area in the picture below is a very difficult area to repair. But it's important. That is the end of the main rear support channel for the rear of the cab and also the area where the seatbelt anchors. The rear cab mounts sit on this channel in the middle of the cab, and the area you repaired supports the cab corner.

 

You are doing a great job
I also had to make patches for areas I could not get parts for like that rear cross member were it meets the rocker & cab corner.
Dave ----