Having recently got hold off a C***rh*m 90 deg gearbox for my speedo drive, Would anyone be able to tell me the thread of the output form the following info,

26TPI with a 18.5-19mm Dia.

Bet this bugger stumps you lot.

ATB Dan.

Well, you asked for an answer, but you'll think I'm crazy!

I can only think it must be 3/4"by 26 tpi, (to state the obvious for a start!) and the only thread that has this dimension is, wait for it................................3/4" BSC (British Standard Cycle thread!)

Bloody hell.your Zeus book must be even older than mine!

I've lost mine!!!

I guessed 3/4" UNF, then realised that was far too coarse, but was the finest "normal" thread I knew of, then I remembered the trusty BSC threads, which use 26tpi across loads of diameters, so I did a quick net search and hey presto!

You may be able to find something to adapt in a bicycle shop as this thread is still used on pushies .
best wishes
Iain