Good morning everyone!

I'm still plugging along with the '78 crew cab project as seen in the thread that gets updated from time to time. I have a request to help with that (and maybe to help future people who stumble across this).

The truck needs both front floor pans and cab mounts to be fully replaced. The passenger side wasn't completely horrible (well, it was), but the driver's side was almost totally gone. That being said, I didn't have much original sheet metal to work with when it comes to a comparison and I'm trying to figure out how it all goes back together. As it stands now, the passenger side floor pan is completely cut out to roughly match my new panel. The cab mount hole in the frame has been repaired and the whole passenger side frame rail is rust-proofed and ready to accept the new parts.

Should I hang the cab mount off of the firewall first? Or put the floor pan in first? Or should I measure stuff and clamp it and weld the two together and put the entire assembly in? Also, what should a new floor pan look like when installed? When I fit mine in it seems to lean pretty hard to the outboard side... is this the way it should be or should it go in "flat?"

Any answers are appreciated, and also if anyone has pictures of the entire process of floor pan replacement (on either side) it would help a lot too, to show the steps of the process. Body work is my weakest skill and so this is going to be the aspect of the restoration that slows me down the most.

EDIT: I forgot to note, I'm referring to the common front floor pans... mercifully, the rear floor of the crew cab is pretty good and will only need minimal flat-sheet-metal patch work in a couple small spots.

 

I have a regular cab, but in reguards to floor slope, they are the same. Yes, they have a pretty good slope from the transmission tunnel > towards the door sill / opening. They are not "flat". I have not needed to replace mine, but I patched them long ago, then top coated them with bed liner and industrial carpet that has a rubber base. I made my patches by cutting from sheet and forming bends, but a picture might give an idea. Floor mats will tend to slide towards the door too. They aren't even just tilted, they have an "arc" like the earth's surface, they are closest to flat nearest the tunnel .... but sockets will take off and roll right out the door, and coffee cups will fall over near the sill. I did these maybe 20-30 years ago, I cut and formed mine with an overlapping seam where replacements are a single stamping. I only had a few holes in the closest to flat area, the majority was good sound metal. I top coated with bed liner and then industrial carpet with bonded rubber, no moisture absorbing jute, etc. Under the floor on the bottom is a sheet of aluminum to block road splash. They may not be show winners, but they'll be there long after I'm gone.

Where the yellow X is is where I found that I had some minor rust, likely started by damp carpet jute backing under rubber mats not drying out. Once a hole rust through, more moisture can get in from road splash kicked up when driving in rain, etc. I removed all the OEM carpet and padding that day. after finding it damp still. The rust holes were minor enough that at first, I just had a few layers of rubber floor mats over it until I "fixed" it more.


For a fair number of years, I just had rubber floor mats that slid around over the bed liner, then maybe 10 years ago I added the carpet stuff.

I have fixed, replaced my sills since, and have stainless steel sill plates over them too now.
Then a very few years ago, I added a hump cover I made.


I'm pleased.

 

Thank you! I'm glad to hear that they are supposed to be sloped out towards the door, I was worried that they were supposed to be flat and that something was very bent.

My floor is gone pretty much up to the crease in the lower part of the firewall. The passenger side wasn't too bad but I may have cut out more than necessary. The driver's side is all but totally gone so it will need to be fully excised. Anyone have experience with that?

 

Did mine a few months ago, well mostly. Never finish welding the drivers side in completely, it's a solid 85% welded.







I did finish the passenger side though.


These are Tabco floor pans. I both recommend & don't recommend them. They fit great & are of thicker material that others (18ga) & used a fancier coating as well. But it was a several month wait to get them.

I also went with a butt joint for welding them in rather than a lap joint. Bigger pain to do, but also nowhere for moisture to hide.

 

I replaced the driver's and passenger floor pans and fixed the passenger side cab mount in my '79.

I have a number of pictures and detail in my build thread, post #18 covers the floor replacement process - https://www.ford-trucks.com/forums/1...l#post21342219

 

If you over lap, I punched holes around the out side to plug weld the patches in.
I then used 2 coats of seal sealer. First with a tube / caulk gun to force the sealer in between the panels top and bottom.
The 2nd coat was a brush on and again top & bottom.
Then I did 2 coats of roll on bed liner top & bottom.
If anything gets between the layers I should be long gone
Both sides were done the same way: floors, rockers, cab corners, rear door post to rocker tie in.






As you can see I did a cab off frame rebuild of the truck, 81 F100 4x2 flare side, over 4 years.
I built it to drive, been on the road 5 years now and over 28k on it. Was out in the pouring rain yesterday for 40 miles most of that at 65 - 70 MPH.
Dave ----