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Monday, June 26, 2017

Triumph Spitfire Body Repair #3 - LH Floor Pan Installation

With the bottom rear of the "B" post tacked in from my last post, it was now a matter of making it more permanent.  My welding skills are still not that great, but it's definitely better than it was. I purposefully made the piece longer towards the back than I needed to allow me to tie in the bottom front of the rear wing from the other side. A bit confusing if you don't have a picture so you'll have to trust me for now.

Not too pretty. The gap at the bottom-ish right will be filled when the sill is replaced.

Mostly ground flush, but no one will see it. Still have the wire harness hole to cut in, but that will be later.

With that done, I could weld in the repair for the heelboard that I had previously prepared in my last post. This metal was a bit thicker than the bottom of the "B" post so it's a bit more forgiving for blow through with the welder, but I also needed to ensure good penetration. I dialed in the welder and went at it.

Fitted up and ready to weld. Forgot to prime it before welding <whoops>

View from the bottom. I welded it from the back to the bottom of the "B" post.

Welded in and primed. Again, not pretty, but better than it was.

Once those repairs were done, I could get to work fitting the floor pan. Essentially, this boiled down to fitting and marking several times to ensure I could repeat my fit up. I used a small flathead screwdriver to etch where the panels met to give a guideline. The cut out of the old floor wasn't the cleanest of cuts so this added a challenge to make the new floor pan match as much as possible.

New floor pan set in, under the old prop shaft tunnel metal. You can see the crooked cut.

It was a lot of trial and error. The biggest challenge I faced was at the front bulkhead. As I mentioned in my last post, the bulkhead had sprung a bit and the inner portion (near the prop shaft tunnel) was set back towards the rear of the car about 1/2" to 3/4". Because I had the front mounted to the 2x4 sawhorse, it was tricky pulling that forward and keeping it still without clamping it to the new floor pan so I could move said new floor pan.

You can see the twist as it should all be parallel to the 2x4 sawhorse.

I was able to get it all sized up, however, and make some adjustments and cuts. Once I thought I had it all good, I set in the rear radius arm bracket from the black car and it fit just how the old one did.

Looks pretty good.

With that, and several other cross-reference points, I was confident that I had the right fit. I used my flange tool to flange the new floor pan. I did not flange the car (and probably shouldn't have when I repaired the front bulkhead). Then, I used my 4 1/2" grinder with an abrasive wheel (used for stripping off paint, not metal; they're great) to remove the paint from both the car and the new floor pan in the area of welding. I wiped the edges down with some acetone to remove any grease/oil and then applied two coats of Duplicolor Weld Through Primer to the welding areas.

New floor pan drying in the sun.

A question that I asked on my favorite forum was the relief in the back of the new floor pan where the radius arm bracket attached. The new floor pan had two, while the old one (and the heelboard) had only one. As is typical with multiple applications, the new floor pans are made to fit all years of the Spitfire and the GT6 and the difference in suspension designs moved the relief. I banged the unneeded relief flush with the rest of the pan.

The other relief was about 2" to the right of the one I needed. You can see the wavy metal where I flattened it...mostly.

Weld-through primer on prop shaft tunnel.

More weld through primer on bottom where the new and old will overlap for the weld joints.

Like I mentioned, because the bulkhead was twisted, it essentially made the car a bit shorter. This caused the floor pan to stick out past the heelboard by about 1/2". Of the measurements that I did, the new floor pan was spot on with the dimensions of the car, so I figured everything should flush up pretty close.

The overhang of the new floor pan beyond the heelboard.

To keep the bulkhead in place and allow me to do the final fit up of the floor, I wedged a piece of 2x4 between the front of the prop shaft tunnel and the inside of the bulkhead to push it forward. I was able to adjust it just enough to get the bulkhead square. With that, I used a mallet to push the new floor pan forward and flushed it up with the bulkhead until it impacted the body mounting bracket. I don't have a great picture, but the floor pan, in the area of the bracket, is sandwiched between the lip of the bulkhead and a flange that is welded to the bottom of the mounting bracket. It will be tricky to squeeze that all together for welding.

Bracket. Behind the screw, the top metal is the bulkhead, the middle is the floor pan, and the bottom is the bracket flange.

Bulkhead and floor pan clamped together.

With the front of the floor pan fit, the rear still overhung but only by about 1/16", so I ground that flush and clamped it down. I also clamped it at the prop shaft tunnel and checked final fit up.

Clamp at prop shaft tunnel.

As I had feared, I did indeed cut too much from the new floor in a few places. I suspected this on my last fit up. This will require a backing piece to weld properly.


I did a final check to make sure the everything appear square and checked the two radio support tower holes and the several gearbox cover holes in the new floor against the old one and it all looked good. I set up the welder, crossed my fingers and let her rip. I spot (or plug, I guess) welded the rear first.

The heelboard welds. I was happy with these considering I was on my back.

Then moved to the front. I used about three vise grips for each weld to keep the metal tight. As I would complete a weld, I'd walk the vise crips down the seam.

Some of the bulkhead welds. Meh.

For the prop tunnel, I tacked it in in several places, then went back and stitch welded as best I could, pressing on the new floor pan as necessary for a tight metal-to-metal fit. This is why I put the new floor on the interior side of the prop tunnel. It would have been miserable to weld on the other side...from the bottom...on my back. I actually got a bead going in a few spots.

Some of stitch welds. Some better than others.

I'm slowly getting better with hearing the weld to know when it's good. I can tell when I blow through and when I'm getting good penetration (or not). So, the experience is starting to pay off. I'm still putting down too much weld wire I think (bigger the blob, the better the job - a reference from my Navy soldering days) but it just means I'll be grinding a bit more.

More stitch welds at the prop shaft tunnel.

I didn't get the floor completely in as I still had the backing pieces to make. With my time winding down, I didn't feel like doing that so I moved on to drilling out the spot welds on the "A" post to sill filler piece. I wasn't entirely sure how this went together so I ended up mangling it pretty good. I should be able to save it, though.

The transition piece removed.

Looks like that hurt! Poor thing.

Finally, I fit up the radius arm bracket, marked the hole for the bolt that comes through the bottom of the floor pan and drilled a hole for it using my step bit, stopping at 3/8". On a side note, I've used this thing quite a bit, including drilling out holes in an old bed frame and it's still pretty sharp!

Bottom hole drilled.

Ready to weld in on my next visit.

I go on vacation back to Maine for our yearly trip on Wednesday, so there'll be no work for a bit over a week. Until next time...


  1. Great progress! I'm encouraged by your enthusiasm. "The Beast" (my GT6) will require both new floorpans, probably both new sills and tons of other welding. I'm also glad to see you're making use of tools from my favorite store (Harbor Freight)!

    1. Thanks, David. Enthusiasm is definitely required and keeps you from crying. Be prepared to find more welding than you think. Wait for a sale at Rimmers to get the panels. It's ends up being about 45% off domestic prices, even with shipping and the exchange rate.

    2. Hehe. I hear ya about not crying. Rimmer Bros has excellent prices for all that metal (and luckily I got a "new" passenger floor and sill from the PO), even without a sale.
      I'm a couple months away from that. Next on my agenda is trying to get the engine to fire - working on the carbs now.