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TR2/3/3A TR3 Shift knob lock nuts?

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PeterK

PeterK

Yoda
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I have looked everywhere and cannot find a lock nut to keep my TR3 shift knob straight. Any ideas or does anyone have a spare?

Thread is 7/16"-32 .

I did find panel nuts in this size but have to buy a quantity of surplus volume and really don't need 20,000 of these.


Also looking for cheese head screws to replace the Lucas screws on the back of dash switches and voltage regulator. Anyone know the thread sizes?
 
I lost mine back about 1962 or so. I've been looking for a long time for one. Luckily the new one I installed in 1990 gets tight at the bottom of the threads at the right place so the raised shift pattern is oriented correctly.

Why don't you guess how much the pattern is off. Say for example, it's off 180 degrees. That's half a turn. Half a turn with 32 TPI threads (0.031" per thread) would mean that if you shimmed the bottom of the hole in the knob with a piece of shim measuring 0.015" thick and tightened the knob onto the shaft, it might stop at the right orientation you want to have.

At least until you find the right nut. If you do, buy a few and I'll be the first to buy one from you.
 
I'm in for one too!

I haven't tried this yet (I'm at least 6 - 8 months from being ready to screw the shift knob back on) but I remember someone once referring to that as a "bicycle thread." Try asking at a bicycle shop?
 
I don't know what the shift knob looks like on a TR3, but I can tell you what I did on my TR6.

I couldn't find a thin nut to use as a locknut, so I took a standard thickness nut and ground it to half its thickness on a bench grinder. I don't remember how I held it, but I was sucessful and kept the tips of all my fingers.

It works perfectly and looks correct as well.

Just my 2 cents ... Good luck.

Matt
 
Are you sure the threads are 7/16-32 and not 15/32-32 ?

Olander has a box of 100 7/16-32 in either plated steel or SS (but no prices or minimum order shown on the website).

McMaster-Carr has the 15/32-32 in several materials. Nickel-plated brass is $2.20 for a bag of 10 (and they have no minimum order).
 
Yep. I used a thread gauge and bolt sizer. The 7/16" hole fits over the shifter and the threads are 32tpi.

I found a place where I can buy surplus lots of "panel nuts" 7/16"x32 but I think I have to buy 1000.

I'll keep looking or maybe make some up.

Can't even find a regular hex nut let alone a jam nut.
 
Aloha Peter,

A bicycle axle lock nut might work. I have used them on my MG to lock the windscreen into the vertical or folded position. I'll check tonight after work.
 
The links from TR3driver prodded my weak brain. The nuts on these sites were referred to as "panel nuts." They are for affixing switches, jacks, etc. to electrical panels.

My day job is guitar repair and I have a drawer full of orphaned panel nuts. 7/16" is NOT a commonly used size in my industry, but not unheard-of. I found only one. But I know they are out there. I am going to one of my electrical suppliers later today. Watch this space. If I find any, I'll snag a dozen and offer them here for postage.

For the intrepid: Go to your local electronics supply store (not Radio Shack -- go find a REAL electronics supply) and find a switch that fits a 7/16" panel hole. Buy the switch (probably $2 - $3 -- a small price to pay for an unobtanium TR part) throw the switch away and jam the nut under your shift knob. Beware of Asian switches with metric threads.
 
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