Saturday, May 7, 2016

Triumph Spitfire Battery Box Installation #3

Sometimes you just can't see the forest for the trees. The preceding week was one of those times. I've been working to get the new battery box in and spending time trying to fabricate replacement sheet metal to repair what time and rust has taken away. After I put the little corner piece on last weekend, it finally dawned on me that the metal I was using, purchased from my local True Value, was 22 ga while the metal on the car was 20 ga. None of the usual suspects around me sell 20 ga steel.

So, I fought with myself about whether 22 ga was good enough; would it be too hard to weld properly; should I just wait and source 20 ga from...somewhere...further delaying my project. I even went so far as to ask on my favorite forum. Being the awesome bunch that they are, some recommended using old body parts from any other car, an old oven or refrigerator or anything else that was thin steel.

Then it dawned on me. You kept that trunk lid for just this purpose. I have the black tub out back, of course, but I've been trying to only use pieces from that for direct installation on the red tub. Most of the reason for this is so that when I'm done with the black tub and want to give it away, the person getting it will have a cleanly sectioned body vice something which a bunch of random holes cut out of it. So, in the back of my mind, it was off limits.

But, the trunk lid from Dot...well, that's exactly what I kept it for. So, up to the attic to get the new abundance of sheet metal of the right gauge. I prepped a square of adequate size and hacked it out with a cut off wheel on my HF 4.5" angle grinder. Auto-cannibalism? Look that one up yourself.

Area selected for removal.

That just ain't right.
With 50-year old, 20 ga sheet metal in hand, it was time to start the form and fabrication process for the new piece. I purposefully cut it quite a bit bigger than was required and slowly snipped, ground or otherwise removed metal a bit at a time to get the best fit that I could.

The pattern.
One of the more tricky areas was the overhang of the top bulkhead (which was part of what I was replacing) over the passenger's front bulkhead. Instead of making this complicated, I just cut several notches in the sheet metal and bent it over with a pair of needle-nose pliers.

The overhang, looking up from underneath. Hopefully this gives you the idea of the notches and bends...and the bad welds from the little corner piece.
I will go back and fill the notches with weld metal. The other part that I still have yet to figure out is the curved area where I had previously found the brass brazed in. As you can see in the picture above, my new part didn't quite solve the problem of the gap. I think I'm going to have to get creative here, but I'm not ready to commit to any solution yet.

The brazed area. Picture obviously well before damage removal. Gives you a good idea, though.

Initial fit up. Still lots of trimming to do.
So, more trimming, fitting, trimming and fitting. My Dremel rotary tool, with an aluminum-oxide grinding stone, was of great help here especially in matching the uneven edges where the two pieces butt up against one another. I finally arrived at something like this:

Bottom shot of the new piece, freshly primed with weld-thru primer. Holes drilled for where I will do plug welds.
I clamped the part in and tried the plug welds. They were not pretty. I was very concerned about blowing through so I had the welder set pretty cold.

Oh my...those are bad. Well, the one on the far left is okay, though without full penetration.
I ground the welds down mostly flush, turned the welder up to "2" and tried again. Thankfully, that try came out much better. I'm sure, as time goes on, I'll become more confident in how long I can pull the trigger without causing more harm than good.

Bottom one still a bit iffy, but much better overall, I think.
After the plug welds were done, I put in a few tack welds as the rest of the part will be butt-welded in. I blew through in a corner that, while not surprising, was not catastrophic. Corners and large gaps between the two pieces of metal make it easier to blow through since there is less metal there to absorb the same amount of heat. What's left takes the brunt of it and turns to plasma.

Some stitching done. The bottom, left-most weld is the corner that I blew through.
With the tack welds I tacked one spot, then moved a good distance away and tacked another and so on. The intent is to spread the heat out to minimize the warping of the metal while still allowing you to get some welding done. Once a minimal amount of tacks were done, I took a hammer and dolly and tried to get it as set as I could get it. That bend the top bulkhead takes as it goes horizontal was a bit of a pain to get right, but it seems to have come in okay.

The weld from underneath. I also tacked in the wire bundle "strap" from the old piece. Far right is that corner one I blew through. Yuck.
That was about as far as I got today. Tomorrow, it being Mother's Day and all, I'm not sure if I will try to get any work done. I'm cooking a pretty involved dinner, too, so we'll see. However, I am very happy with how the day went and my confidence continues to grow. Still a lot of work to do, of course, but I'm making genuine progress.

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