By John Niolon
After I drug my beauty home and rolled it off the trailer I started my
survey. At first glance the floorboards looked pretty sound. After I
removed the seats and scrapped off the rubber mats, it looked worse
than before but still not too bad. After I soda blasted the complete
cab I realized I had a sieve for floorboards. I was surprised I
hadn't stepped through them already.
thing rubber mats are good for is holding moisture and promoting
rust. Years of abuse and a half inch of crud in the floors
compounded the problem. No doubt they would have to be replaced.
floors are reasonably flat and neatly divided into three major
sections. #1 The sloped toe board section that starts at the bottom
of the firewall and extends down at an angle to the main flat
floorboard. #2 the front portion of the flat part that has the
transmission inspection/access hole in it and #3 the rear flat
portion where the seat is bolted on.
poking around with a sharp awl, we decided that sections one and two
had to go. The section beneath the seat was still nice and sound and
would make a good transition point for the added sections. The seat
has a raised rib across the width of the truck which strengthens it
and cuts down on the 'oil can' effect of a large expanse of flat
decided to use 14 gauge material (.0767) for the floor panels. It's
a little thicker than the original floors, but it will add a little
strength to the floor and mostly it was what was readily available.
plan was to use two separate pieces for the toe board and the
floorboard with a angled joint piece where the two came together.
The angled seam piece was approx. 3 inches high and as wide as the
cab and bent to the original angle (approx. 135°).
began by cutting out the toe board section first…( this isn't
my beautiful head… but the hairline is the same)
next step was to cut out the floor section, but we were concerned
with the cab spreading so before we did the cut we added a brace
between the cab sides to prevent it from spreading. Unfortunately
the one-hour processor ate my film with these pictures, so I didn't
get pictures of these steps. A sketch will have to do here…
torch cut the area shown in the picture below and left a 1" lip
around the perimeter for support and to give us a clean edge to weld
against. It's hard to see in this picture but the sloped panel and
the flat panel are joined at their joint with a angled seam piece.
It will be apparent in further pictures when we cut the transmission
decided to cut around the cab mount points… the metal there
was still in good shape and it would only make the job more
difficult. Your mileage may vary here.
the old metal was cut away, the new pieces were held in place and
marked for trimming, then tack welded in place. The final trimming
was done and the panels were stitch welded in place. We used roughly
a 3 on 3 weld (3" of weld every 3") the seams will be
filled with seam sealer (silicon, body seam seal…etc) for
water proofing and protection.
used the angled seam joint piece for convenience but it also adds
some structural strength to the floor panels. The double thickness
there stiffens up the floor and cuts down on that "Oil Can"
effect. It was first tack welded to the flat panel which was tacked
into the cab, then the sloped panel was set into the angled piece and
tacked in. It gave us a third hand to hold everything together.
the final fitting and grinding was done we cut out the brace inside
the cab and sprayed a coat of primer on both sides… here's
what the final product looked like.
course all of this has to be done with the engine/transmission out of
the vehicle, or at least it's easier that way. You could make your
cuts for the transmission hole before installing the panels but it's
much more difficult fitting, grinding, etc. Another option would be
to jack up the cab above the transmission and do the work…still
more work. My truck was being done frame up so the engine and
transmission were not in the way.
you will have to install them to make the cuts and I decided to
remove the front cab bolts and jack up the front of the cab. Then
the engine and transmission were installed and the transmission hole
cut was measured and transferred to the floor boards. We found the
widest part of the transmission, added an inch to each side and
drilled through the floorboard at that point. Then from the top..
using a framing square we squared up a hole and marked it on the
floorboard. The toe board cut was a little more complicated since it
wasn't square and had to be cut around the bell housing. With some
preliminary measurements I made a "first cut" mark, knowing
some trimming would have to be made.
drug out the plasma cutter and made the main cuts in the floor board
and the preliminary cuts in the toe board. After doing this and
dropping the cab..checking clearances… cutting again…checking
we came up with the final fit.
plan to use a metal transmission cover offered by Mid-50's F-100
instead of trying to roll/bend one of my own. Theirs is preformed
and looks very nice.. It also accidentally (and incidentally) fit my
about the whole thing. It's not a terribly complicated project. A
plasma cutter would have made the removal a little quicker and a wire
welder makes the welding easier than stick welding.. If you need
access for master cylinder filling for an under cab booster, then
other holes need to be cut in the floor and access panels made. If
the rear portion (under the seat) needs replacing I'd stress using
adequate bracing inside the cab so the bottom does not spread and
distort the shape of the cab and really make a mess of your cab
mounting points. You probably won't notice it until you have the
panels welded in and place the cab and then the repair would be more
than any of want to tackle. Good luck!