- Wed Dec 30, 2015 11:53 am
#53684
Just to confuse matters, the grease nipples on my NOS half width rear hub were M6 - or, at least, M6 fitted perfectly.
...and we thought it was all getting clearer!
What you **might** have there Count Johnny, if your half width hub is a Redditch original, is a 0BA thread (as found on original Smiths Chronometric speedo case mounting studs), the 6mm thread is a very close match, but if your hub is one of Indian origin, it could well just be 6mm! How old is new old stock in this case?
A.
You could have M6 from the 60s or it could be 0BA which is also 'metric' made to nearest preferred inch-size. 0BA is approx 6mm O.D. with approx 1mm pitch so you may well get a 'Class B' fit of M6 to 0BA. The BA-series were originally for modelling at mm-to-inch ratios; I don't mean toys, it was quite often necessary to build scaled-down models of items before full scale, a job often handed over to apprentices. So BA taps and dies would have been very common in an engineering works. Did RE fitters and machinists own their own tools like they did at GEC? The thread size could depend on what the chap had in his tool box.
. happy new year