The locking ring measures up at .165" thick with an outside diameter of 1.825"...
There are four equi spaced slots which are .145" wide by .125"deep...As described earlier the O.D has a very fine cross cut knurl applied....
Original finish nickel plate...All dimensions are as measured but nominal due to original production tolerances and light damage of the part in places....Ian
Thanks Darren...The locking ring is very light so may well be bicycle...The tap is available as it has a motorcycle application for the cush drive nut and perhaps other items on earlier machines.....Ian