Triumph Spitfire Chassis Restoration #8 / Repair #6

Sometimes you have, what we referred to in the Navy as, a "brain-fart". I'm sure we didn't coin the phrase, but it was often used. Well, I must admit that I had a big one. I got that rear differential all nice and pretty, refreshed and wonderful and it was great! So proud of it, I was, that I posted the result on my favorite forum. A quick reply from one of the regulars "Looks great! Did you put a drain plug in it while it was apart?" My heart sank. Of course not! But, I was smart enough to order a drain plug for just that purpose, but got too far ahead of myself and forgot. So, the stupid tax will be paid. It will come back apart and taken to a machine shop for the work (I don't trust myself to do it). I'll renew the gasket and re-do the paint, as required, of course. Just glad I didn't put oil in it!

Pretty, isn't it? I'll try again, I guess.

I also was able to get the locknuts off the studs that bolt into the top of the differential that hold the leaf spring down. Heat and PB blaster worked on most but for some I had to cut the bolt. I'll be replacing all of the studs, though, because upon further inspection they looked pretty well beaten up where they were exposed to the elements. Besides, at about $3 each, it's worth the proper thread engagement.

Whoops. What I get for using the cutoff wheel.

I was able to spin this one off. If you look closely, you can see the degradation to the threads above the bolt as opposed to below it.

Other than that and my trunnion troubles, things have been moving along. I thought I was wrapping up cleaning up the frame until I found some more cancer as I mentioned in my previous post. I took the advice of the guys on the forum and investigated, of course.

Based their sage advice, there was going to be metal replacement regardless of the extent of damage. My initial thought was that I may be able to just do some weld buildup and fill the pin holes that I found. What I learned, however, is that the pin holes don't develop from the side you see them on. The pin holes develop as extensive corrosion on the other side of the metal that finally manifests itself as pin holes on the visible side. Such was the case with this portion of the frame.

Best overall picture of the damage. The frame is flipped over here so this is the bottom of the passenger's side.

After removing some metal that was obviously damaged and also providing an inspection window, I found some rather extensive damage.

The first cut. If you look at the far right corner, you'll see some black "stuff" that fills the corner. That was a grease-grime-paste-? like something. Yuck!

Looking down the abyss. Not good.

I sprayed some Purple Power Citrus Cleaner in there and cleaned up as best I could and re-assessed. And, of course, found more damage.

This is the inside of the frame, mostly opposite the cut above. You can see the light shining through. I had not located these holes prior to this, but the interior corrosion was obvious.

I cut that out, too.

Top view of the extent of the cuts. Remember, again, the frame is upside down here.

View of cuts from the outboard portion of the frame.

View of the cut from the inboard portion of the frame.

If you look closely, in the above picture, there is one very small pin hole that I did not cut out. It's just to the left of the left vertical cut, just less than mid-way up between my Sharpie line and the cut itself  (a black dot surrounded by a grey-colored area). The internal damage extends just to this hole. But, with the perpendicular metal part that sticks out (this is where the steering rack bolts up) being attached at this point, I decided not to cut that far. My plan right now is to just preserve the inside really good (POR-15) and fill the pin hole incidentally welding the replacement metal in. Hopefully this works. My concern is that I will blow through the thinner, corroded metal too much and get stuck. We'll see, I guess.

As for the replacement metal, I fortunately still have the mostly-intact frame from the black car in the back yard for just this sort of issue. So, I took my trusty sawzall out there and hacked a very large portion of it up before I left to accomplish the work I've already explained.

A quick shot of the portion that I cut out. I cut more than this, but this was before I went at it.

Once I had bounded the problem on Dot's frame, it was over to the black car's frame to hack away at it. I over-cut, of course, to make sure I have enough extra material to grind/cut away for fitment. The only area of concern was cutting close to the suspension mounts and the interior reinforcements that the frame has for them. Some creative cutting with the cutoff wheel and sawzall, however, and I was good. I wanted to preserve the interior reinforcements just in case.

Obviously a nesting area. And recent, too, given the green acorn! Chipmunks, probably. Little bastards are all over my backyard!

I started fitment, grinding and cutting to fit up the replacement part. What I didn't have, however, was cardboard to make a template. When I started to get to the point where I was afraid I may cut away too much without making a template, I stopped for the evening. I put the donor piece in some vinegar to soak until Friday just to get the paint and surface rust off.

Side view of donor piece. Bottom is the outboard side.

Top view, with anti-roll bar mount cut off. 

All in all, not bad for about 3 hours of work, I guess. This weekend is committed to family events, so it will be another several days until I have a chance for more work. I want to get over there tomorrow (Friday) to get the replacement metal out of the vinegar. I'll neutralize it with water/baking soda then blow it dry in preparation for more fitment adjustments.

If you remember, I'm on a timeline with the rented garage. Therefore, I'd really like to have the frame done by the end of October. Since all of the other suspension bits are already ready to bolt up, it will be a quick re-assembly. Then, on to the engine through the end of November (given no surprises, of course) and then body work in all it's pain and glory over the winter. If I can be ready for paint (or at least landing it back on the frame) by April, I'm going to be happy!