Allan, sorry, I misunderstood you. My problem is about the thread for the rotor nut, not the sludge trap plug..
Rgrds,
Lars
I am trying to fix a bad thread on my two spare crankshafts. One is the older one with 2 plugs for the sludge trap and one is the newer with only one plug. Threads on both crankshafts are 5/8" 20 tpi but which type of thread, CEI, UNF(S) or..?
Thanks!
Rgrds,
Lars
Appologies Lars, theres several threads on the BSA crank, though I guess theres only one at 5/8", even still though the same logic applies. I have yet to see one which is different. The part number (29-2023) remained the same part number from 1962 until the bitter end. There isnt a UN size thread anywhere on a pre 69 bike (unless a previous owner put it there).
There are however plenty of nuts on the market which have not been machined properly. Same with clutch mainshaft nuts. Before I owned a comprehensive set of taps and dies I would end up buying a bag of 6 of each to find only 1 which fitted.