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TR2/3/3A Screw Post Coils

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CJD

CJD

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Yesterday I did the annual tune up on the TR3A. Even after R&R'ing the entire car, I learned something new. When I took the high tension coil wire off the coil, it had a simple press-in connector in the end of the wire, with a rubber sealing cap around it. Just like when I bought the car, and just like when I finished the restoration.

I went to spread the press-in connector for a tight fit in the coil, and realized something was not right. Well, having worked on the TR2, I now know what a screw in coil looks like...and it turns out the TR3A has one! All that has been holding the coil wire in for at least 3 decades is the friction of the little rubber cap.

Guess the old girl was jealous that all the parts were going to the TR2. This will be the first part I'll have to find for the TR3 in over 3 years!
 
I am regularly showing my ignorance.
but I fall back on " no such thing as a dumb question"

so what does a screw in coil look like?

thx CJD.

Guy
 
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Where the high tension wire goes into the coil there are threads on the inside and the HT wire goes through a screw top piece that then screws down into the coil, thus holding the HT wire in place.

Sorry the picture imported sideways, tilt your head to the left, LOL
 

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I'll take a pic looking inside the coil post when I get home. In the mean time, the coil looks pretty identical to a later coil at a glance, but the hole is larger, so a normal coil wire will never "click" when you push it in. With a closer look you realize that the sides of the hole are not metal, but plastic, and there are threads.
 
One more comment about the screw top coils.

First, I got a screw top coil that was painted black from one of the big three suppliers, I believe it was Moss.

When my restoration was nearly complete I found an original looking screw top coil in nature aluminum finish in England.

Each came with a the screw top part, and when I when to install the aluminum finish coil I had to change the screw top also since the length of the part that screwed into the coil was a different length. As I recall the aluminum finished coil required the longer screw top.

The Moss catalogue also shows the split brass washer required to hold the HT wire in place.
 
My '59 still has its original screw-top coil, dated 8/59, which matches the month it was built.
Don't know if that is especially noteworthy or not...
Went to check if the split washer Vila mentioned was still there, yep!
 
I guess if you had a carbon wire, you should lose more than a metal wire with one of those round copper slotted washers, but either way you would lose something because the connection would be a little lose, but again that tight rubber boot might hold the wirer in place, and if I remember my auto shop of the sixties, it takes 20K volts to jump through one inch of air and a coil should do that. In Washington State something like that would contribute to poor starting because of cool dampness. I guess Texas where you live is dry dry. You probably saw that you get one of those screw down deals. The correct ones with the older flared look are getting harder to find and so are the old coils. I bought a couple over the years, but really have not put them to a road test. I figured I would get to it someday, but again not fun to break down in traffic.
 
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