New Floor Pan

I ordered the Dynacorn 3648D 1969-70 Mustang complete floor pan. When they say complete, they mean complete. I ordered a few parts not thinking they would be included in the box. I was mistaken.

I expected just the floor pan. I was surprised to find the seat platforms, all of the floor plugs, the mounting brackets and the rear torque box upper covers. I sent the other parts I had bought back.

In a twisted way to look at things, I found that it was a good thing that I replaced the cowl. Because the cowl came out, the windshield did also and because the windshield was out, it made it that much easier to get the floor pan into the car.

It’s odd to see the floor all one color, although technically black isn’t a color, whatever you want to call it, the floor is all of that. I like it.

Drop the pan into place and…WTF???

The floor is too narrow. People on the forums have encountered this and some of the folks say that the pan will taco a bit in transit and all you need to do it stretch it into place. Nope.

Stretched the pan by clamping the sides to the rocker panels. It was a fight. I thought that was it but certain things were not lining up. Most pronounced is were the trans tunnel of the floor mates up with the firewall. There’s a gap on either side of the tunnel down near the floor.

Remove the clamps and the floor conforms to all of the little grooves and angles. Dammit, this floor is too narrow. Even in the back where there are these little winglets that fill the spot behind the torque boxes do not touch the sides.

I think the floors were short by 3/8 of an inch. I don’t know how other people would handle this. For me, I kept thinking about what freight would cost to send this back and then wait to get another one that’ll probably have the same issue, if the forums are any indication.

I decide to section this thing

I cut the side rails off by 1/2 inch. The hard part was making 3/8 inch strips without a stomper type metal shear.

The idea is to clean up all edges, tack the 3/8 inch strips to the 1/2 inch strip I cut off of the sides and then tack the entire strip back onto the floor pan. Do this to both side and this should bring the floor width to where it should be.

I thought it would be faster if I could Tig weld the floor back together again. Never mind that I’d never used a GTAW before. How hard can it be?

As it turns out, a real bitch.

I did my homework searching the net, looking up info about the electrode, the filler rod, gas flow, amps.

I set up the welder and even had the floor pan at waist level so I wasn’t slouching. The first bead was nice. I got the metals to pool, added the filler and got it to flow. Did a short bead so as not to overheat the metal and stopped. Moved to the other side of the floor, hit the pedal and was met with a super bright arc and metal nearly vaporized. WTH? Tried it again and the metal wouldn’t pool. It’s gotta be me doing something wrong. Regrind the tungsten, check the amps, turn up the gas flow a little, visit the toilet, come back after washing my hands and try it again. Perfect bead. Hmm, it was me.

Move to the other side and vaporize the metal again. This continues for the rest of the day. I cannot get the handle on this thing. I finally give up and go back to my trusty Lincoln Mig welder.

The beads are bigger than I like but at least I’m making progress.

It takes me a couple of days to fit, weld and grind on the floor pan but when it’s put into the car, the gaps along the sides and the rocker panels were gone.

Take another day or so to widen the little winglets in the back and after a little self-patting on the back I start chopping up the transmission tunnels in preparation for the Tremec.

In preparation for putting any substantial weight on the front of this car, I get some square tubing and weld the pieces to the floor supports and the front of the frame under the radiator support. I don’t need the car falling off the jacks and making even more work for me…or a bonfire when I lose it and just set the whole car on fire

I dig out the Fe block, bolt on the bellhousing and then the Tremec and then the whole thing goes into the car to see where it’s hitting the floor.

I try taking as little as I can from the tunnels. In hindsight I should have just rebuilt the entire tunnel, just to be certain.

I end up cutting the top off of the tunnel almost the entire length of the transmission. I have to guess on the exact height of the tunnel to the transmission as the floor is not bolted down. I have to stay aware of float.

When I think I have the necessary clearance, I now have to build a new top for the tunnels.

For the firewall side, I recycle part of the tunnel from the old firewall. I don’t need a whole lot. Once that’s looking like it might work, I turn to the floor pan.

I grab some construction paper and make a rough template of what I think will work. Next step is to use the template as a pattern to cut a piece of 18 gauge steel and then it’s a matter of beating the steel into submission until it forms itself into the shape I’m thinking of.

I think it will work.

Test fits never take just one or two tries. I lose count of how many times I’ll fit something before I’m satisfied that it will be good enough.

I’m finally satisfied how the tunnel hump fits so I can finally tack it into place and then test fit the whole floor.

I run into a small problem. The transmission tunnel support. the arch that goes between the two floor supports. It won’t fit over the transmission. At first I’m thinking that this is real bad because the support is also the anchor point for the transmission cross member but that’s not as bad as it sounds as the transmission mount is now a lot farther back on the transmission so the support mount doesn’t matter.

I’ll move the tranny tunnel support farther back so it lines up with the trans mount. Nope. The top of the loop is right where the shifter is. Dyancorn makes a support that is big enough to clear the Tremec but why bother? I’ll find out if the decision is sound or not once the car is on the road. For now I’m not putting the support back in. I’ll have to fabricate a transmission mount.

Weld the trans tunnel humps to their respective locations, clean up the welds, use a little All-Metal to fill the low spots, which there are many, and once that’s smoothed out, the whole thing gets a coat of grey primer. I think it’s primer. It’s grey anyway. It’ll sit for a couple days. I need a break.