Hi

Can anyone inform of the thread type found at the top of the girder fork stem

It's very fine - I would like to run a die around mine as it has suffered lower down over the years

Hopefully with this, I can order a die from a supplier

Many thanks

Job

email (option): Jonnyob1@googlemail.com

It's a cycle thread but an unusual one..1 1/8" x 24tpi..

It's noteworthy that cycle thread is not always 26tpi.. 20, 24 and 26tpi variants are all commonly used...

There is quite a lot of the 20 tpi form on the M20...The 24tpi form, when used, is usually on things like hub locking rings and steering stems...

The Tap and Die Co. in London will probably have it but it won't be cheap!... Ian

email (option): ian@wright52.plus.com

Thanks Ian

Will call after I shift this flu thing I have

Job

email (option): Jonnyob1@googlemail.com

Hi John,

I bought a thread file a while ago and have used it quite a few time already. Works pretty good to clean up damaged threads.

Henk

email (option): ahum@quicknet.nl

John, if you have access to a lathe that can cut imperial thread pitches another option is to indicate the headstem very carefully, set the lathe up for 24 tpi , set the threading tool square to the headstem and manually 'synch' the lathe to the existing threads. This takes a bit of fiddling but can definitely be done.
My old clunker has change gears so relatively easy to 'slip' the gear train to get things in synch
Once you are certain you are in synch you can engage the cutting tool very lightly and manually turn the lathe to clean up the threads.

I tried it on a headstem of one of my dismantled projects today and a section of thread that was slightly flattened cleaned up nicely.

email (option): rays54@hotmail.com

And there is always the "poor mans dienut"
Get a nut of the correct pitch , dose not even need to be the exact same diameter.
Cut it in 1/2 lengthways then rub the ends on an oil stone till you have a nice flat surface and sharp edges.
Back in the 30's where this tip comes from they said to clamp it together over the thread with a machinist clamp or U bolt but now days a big Vice grip works a treat.
Back in the 30's the instruction was to coat liberally with lard then work the nut up & down the thread.

This actually works perfectly and I have done this many a time.
If it stops cutting then a few strokes on the fine oil stone refreshes the edge and you are back in business.

I think it also gets a mention in Radco's Vintage Motorcyclist Workshop, which if you don't have, get one now. It is kicking around on the web as a downloadable & printable file.
Not as good as the real book but print it out and read it cover to cover it will save you thousands.
You can do almost the same thing with a bolt and a fin cut off wheel to clean up an internal thread , but you need to be able to make a very clean cut and it can only go 1/3 full depth.
I have had some success cutting a V notch as well.
In fact I have just finished cleaning out the 11mm x 1,25 threads on my L 300 block.
Only place that kept the non standard size tap wanted $ 139 (Aus ) for it.

email (option): bsansw1@tpg.com.au

Thanks all

I'll try obtain the die first but if an astronomical price will look to the other suggestions you have kindly provided

Thanks again

Job

email (option): Jonnyob1@googlemail.com