Proper tap size for the 1 1/8" top nuts, damper rod

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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martinbuilt AJS
Posts: 26
Joined: Thu Dec 31, 2020 3:52 am
Location: Pennsylvania USA

Proper tap size for the 1 1/8" top nuts, damper rod

Post by martinbuilt AJS »

The description makes sense, i hope.
I need to buy a tap for the hole that grabs the damper rod. I can't tell if chasing the threads will do it, but it's pricey to keep ordering new parts from the UK.
If anyone can recommend a set of quality cycle-thread taps, that would be helpful.
I ordered a set on ebay, and i'm not convinced they are correct. Either the pitch, or the thread profile is off, as they don't mesh well with the original fasteners.
Thanks
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dave16mct
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Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: Proper tap size for the 1 1/8" top nuts, damper rod

Post by dave16mct »

I think it's 5/16" BSCY Cycle thread. 5/16" x 26TPI. I'll check after dinner! All cycle threads from 1/4 to 1/2" are 26 TPI. From 1/2" upwards they can be 20TPI.
Dave
Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Proper tap size for the 1 1/8" top nuts, damper rod

Post by Mick D »

Hi

Tracy Tools will supply boxed sets:

https://www.tracytools.com/taps-and-die ... wooden-box

Or you can save money and only buy what you need.

The thread at the top of the damper rod is 5/16" x 26TPI BSCY

Regards Mick
martinbuilt AJS
Posts: 26
Joined: Thu Dec 31, 2020 3:52 am
Location: Pennsylvania USA

Re: Proper tap size for the 1 1/8" top nuts, damper rod

Post by martinbuilt AJS »

Thanks for the quick replies. I'm going to get shopping!
56G80S
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Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: Proper tap size for the 1 1/8" top nuts, damper rod

Post by 56G80S »

+1 for Tracy Tools

Johnny B
martinbuilt AJS
Posts: 26
Joined: Thu Dec 31, 2020 3:52 am
Location: Pennsylvania USA

Re: Proper tap size for the 1 1/8" top nuts, damper rod

Post by martinbuilt AJS »

They have everything. Tons of obscure sizes/thread types.
Thanks again for that link
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