Sunday, December 18, 2016

Triumph Spitfire Chassis Restoration #17

Darn snow! Meant to get over to the garage all day on Saturday, but the snow forecast busted a bit so instead of 1-3" with it changing over to rain early in the morning, we ended up with about 5" and it not changing over until mid-morning. By the time I was confident the roads were good enough to drive on, it was essentially too late to make it worth it. I did get some work done on my weeknight, though. Everything is still focused on getting the chassis back together. I learned some new things, figured out some new problems, and otherwise had a great time!

First, you may remember that I was concerned with my thread protrusion for the rear damper upper attachment points. I had purchased new nyloc nuts and they were rather tall. This resulted in insufficient thread protrusion (I'm looking for at least one whole thread, preferably 2-4) with the threads just barely engaging the nylon at the specified torque.

As you can imagine, the Navy is pretty concerned with fasteners and their proper use. Turns out a warship has got to be built pretty solid and, just as important, maintained that way. In a submarine this is even more important since we sink her on purpose. A program that came out of the loss of the USS Thresher (SSN 593), and reinforced by the Challenger disaster, is the SUBSAFE program. SUBSAFE is a quality assurance program that provides objective quality evidence (OQE) to maintenance and repair work on systems designated as SUBSAFE. SUBSAFE systems include seawater systems, emergency main ballast tank blow systems, escape hatches, etc. Essentially, if it is a system that could allow seawater into the ship (intentionally or not) or could impact ship recoverability (like the rudder and planes), it is SUBSAFE.

Certain aspects of fastener installation are important to be observed. A common specification that we are used to in dealing with in our cars is torque. Something that is not so common is thread protrusion. The designers deal with this and, as long as you re-use the nuts and bolts, you don't normally need to worry about it. But, if you are replacing hardware that may not be exactly as original, it becomes a concern.

To ensure proper engagement, a threaded fastener should extend beyond its nut a certain distance. In the Navy, we have manuals called Naval Ships Technical Manuals, or NSTMs. Most, if not all, of these are publicly available. The one that deals with fasteners is NSTM 075 (this link opens a pdf of the NSTM). There's all sorts of good stuff in here. For our discussion, the pertinent section is 075-7.5, Length of Thread Protrusion, which specifies at least one thread protrusion. In my case, I didn't have that.

Threads just barely flush with nut end. Improper thread protrusion means the fastener may not be at full strength.

There's a bunch of good stuff in that NSTM. Use of washers, when to replace a nyloc nut...lots of stuff. The table of contents is pretty good, too, so if you have a specific question, you should be able to find it.

Anyway, my solution was to find a shorter nut, which I was able to do. I didn't take a picture of the nut that I pulled off (I assume it was original), but if fell somewhere in height between the tall one and the short one.

Tall nut on right, short on left.

I don't believe that the shorter nut will degrade the fastener as much as the taller one would due to the insufficient thread protrusion.

New thread protrusion. About 4 threads there...perfect!

Since I hadn't done it and didn't want to forget, I greased the rear bearings also.

Good enough!

Sticking with the rear suspension, I also assembled the rear drum brakes. This went pretty well, with the aid of the workshop manual for assembly. And they are not very complicated, so there's that! The PO had purchased all new rear brake stuff from SpitBits as part of their kit so it was just a matter of putting it all back together. There were a few things that were not included in the kit, but the workshop manual saved me.

First was installation of the wheel cylinder and operating level for the emergency brake. The wheel cylinder is essentially the hydraulic guts of the whole drum brake. It's fastened with a two-piece horseshoe-shaped spring clip assembly.

First spring slid on (emergency brake operating lever not shown here).

And the second. They "lock together to hold it it. Tight, but not immovable.

Emergency brake operating lever.

The emergency brake operating level comes in from the back of the wheel assembly and the two nubs on it fit into recesses in the housing of the wheel cylinder. Definitely something better seen than explained.

Lever and wheel cylinder mating. The wheel cylinder is not clipped in in this picture.

I then bolted in the adjuster, which is the bottom pivot point for the shoes. I then installed the springs onto the brake pads and got them installed. This takes a bit of doing as you have to expand the springs, obviously. Most importantly is the proper orientation of the springs and their attachment to the shoes.

Springs installed.

How the upper spring is oriented through the shoe.

And how the lower spring is oriented.

And there it is!

I had mentioned that not everything was included in the kit. Specifically (and only, actually) was the cotter pins that capture the emergency brake operating lever through the leading brake shoe. I didn't have these handy, so another trip to True Value is in my future!

Close-up of where the cotter pin should go through the emergency brake operating lever.

Internals all done (except that cotter pin, of course).

Next up was connecting the emergency brake. Ran into a problem with "new" parts here in that the pin that holds the cable to the operating lever wasn't tall enough. The operating level and fork end are original, so I can only blame the pin. This was a new part from SpitBits.

Close, but not quite tall enough. There is a washer that goes in the bottom which completely covers that hole.

I was able to find one of my old ones (and only one, unfortunately, given that I should have four of them from the two cars!) and the difference was readily apparent.

Sorry for the blurriness. But, you can see that the hole is short but just about as much as it needs to be!

I'm going to add the pin to my True Value list, but I'm not confident that I'll find one. We'll see how that goes.

After that, I started in on the brake line kit. Pretty nice stuff. Automec is a British manufacturer that makes kits for all sorts of British cars.

The kit.

The lines come pre-cut to length with all of the proper fittings, but they are not bent. Each line is labeled, by number, with it's particular location and this is referenced to a generic list that comes with the kit. So, it is a simple thing to match the brake line number with the location and go from there.

A portion of the list. Again, this is a generic list and I only had a few numbers on my pipes...simple kit, obviously!

The hard part, of course, is bending the pipes! I got a simple pipe bender and between that any my hands, I got pretty close.

This is the driver's front brake line from the splitter to the wheel. Top is what came out, bottom is new. Ready, go!

One thing I learned is that there is such a thing as a "generic" brake line flare, which the Automec kit uses exclusively on both ends of the brake lines. I was concerned at first, but a quick inquiry on my favorite forum alleviated my concern.

The Automec kit on top (universal flare), the original on bottom (bubble flare). 

There is still some bending to do, but I got pretty close!

As close as I got that night.

That was about it. I also figured out that I had the brake line holder for the caliper in backwards. This lead me to discover that I also used the wrong length bolt for the upper wishbone mounting. This is going to truly be a pain in the rear, but better it right than not. I'll fully explain in the next installment!



Unfortunately, that black hanger piece is not installed properly. What a can of worms that opens!

2 comments:

  1. It's coming together! Soon you'll have a roller that will also stop!

    Something I've always wondered about is brake lines. They come all coiled up, but some of theM (e.g., the ones to the rear brakes) are mostly straight. Do they straighten easily? I can imagine myself just never getting them to be the right shape....

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    Replies
    1. David I just finish up all the lines tonight. Took me about 2.5 hours start to finish. They do straighten easily because of the copper that's in them. Post will be up in a day or two!

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