Monday, July 22, 2019

Sill to B-Post Rework | Roundtail Restoration

Sorry, folks. I've made several videos since I last updated my blog, but only two of them are really work in progress videos. However, I did do a series on redoing the seats, which I'll provide below:



Definitely a topic that lends itself much more to video than it does words. The link is a dedicated playlist for all three videos.

I also am in the midst of a 4-part series on threaded fasteners using the lessons and directions that we used in the Navy. It's a lot of me talking, but it's full of information. Here's those:



I tried to make these videos shorter, but I talk to damn much. I should get the last one out soon.

As for the work that I did in direct support of the restoration in progress, most of it has centered on some re-work. I never liked the area where my passenger's side sill met the B-post. While contemplating the extent of that rework, I had a sort of epiphany as I stared at it; I'm probably not going to have the car on the road this season, so I may as well just get it fixed right. Otherwise, it would stare at me every time I walked up on the car.


Construction-wise, the sill sits on top of a flange in the B-post. I don't think it was ever spot-welded (from the factory) in this area, but it was brazed.

When I was struggling with my gaps, a very kind gentleman from England who works in the industry was kind enough to send me some pictures of the last Triumph Spitfire, in Inca Yellow, that rolled out of the factory in Canley. It rolled right into the British Motor Museum and is the top car in a 3-car rack (along with a TR6 and MG Midget). It's only got about 10 miles on it, so this was the standard coming off the line in August of 1980. One thing I will mention is the gentleman told me that the tooling, jigs, and fixtures they were using by that time were over 20 years old, well past their "sell by" date (which is about 7 years).

The sill-to-B-post transition. Notice the brazing spot.

As an FYI, this is the front sill cap. Guess that little edge that I left on mine should have been ground down.

On the stop shelf. You can just see the top of the Midget below it.

Now I knew the look that I needed to recreate. The metal had been damaged a bit when I was putting the sill in, causing the gap. Since there was no access behind it, I had to cut a window to make the repairs.

Tracing out my cut area. Sorry that I didn't take a "before" picture.

This was easily accomplished with a metal cutoff wheel.

The window to the repair.

The flange on the B-post needed some help. It had a few holes in it and just needed some love and straightening. I did the best I could.

After some work.

Once I got the flange as good as I was going to get it, it was time to fit the cut-off piece back up to check fit. Not so hot.

Huge gap! Time for some weld build-up.

I did a weld build-up right at the vertical-to-horizontal transition near the top. This corner should be relatively sharp but was rounded at some point during the sill replacement (or old sill removal).

The step of the flange in the B post was deep enough that the sill didn't rest on it (guess that's why they didn't spot-weld it). But, I needed something make up the gap, so I welded a flange on the cut-out piece and removed some of the damaged flange that was therefore no longer required. It was kind of a hybrid flange, I guess you could say, but it made it easier to get it fit up.

Damaged flange area cut out. The weld build-up in the corner of the B-post is also easier to see here.

With that figured out, it was time to weld it all back up. Getting it all sized and adjusted was not that easy since it was a blind weld, so to speak. I couldn't hold the cut-out piece in place with a magnet and see what gap I was going to get at the same time, so I used some tape. The video does a better job of showing this. Eventually, though, I got it lined up and welded in.

Piece replaced. That rounded corner at the union is much sharper now.

And with minimal gap.

With it all welded in, I got some fiberglass filler on it to provide some reinforcement (I should have epoxied it first...grrr). I was careful to keep the fiberglass out of the joint itself because I was afraid it would eventually crack since I'm sure this is a flexible joint.

Fiberglass filler applied and curing.

Sanded down good enough.

I sanded the fiberglass down to get the high spots off. I'll get it into epoxy primer on the next visit and then do "normal" filler work on it to get if flat.

What the gap and union look like after the repair.

Once all of the filler work is done and epoxy is down, I'll use seam sealer to seal the gap that remains. It should also give it a cleaner look as well.

Speaking of cleaner look, I also used some polyester filler, after scuffing the epoxy, to fill some of the areas on the upper A-post that needed it. I'm not too concerned with this area since it'll be covered by the bonnet a majority of the time, but there were definitely some spots that needed the attention. Namely the sill to A-post area had some decent gaps. The polyester filler, along with the epoxy that will go over it, should keep any moisture out of there.

Polyester filler applied and in the process of being sanded smooth.

Next post, I'll finish up with the sill repairs and move on to the bonnet, which also gave me some problems. Thanks for reading and watching!

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