I was messing around with my A restoration the other day trying to determine how much wear/ovality might be present in the headstock, etc. (It's not that easy to do consistently/accurately with callipers). Anyway, by coincidence a colleague contacted me asking about the same bearings. He wanted to know what grinding work would have to be done, and what dimensions to work to, to convert postwar cups and cones for Series A use.
It seems from my discussions with 'A' enthusiasts, that the predominant 'A' system was originally "cup to cup"; ie 4 x F128 ground in a simple 'U' shape. I have a pair of worn ones on the desk in front of me. They are much reduced in height compared to a postwar pair with balls in place, moreover there are tiny differences in OD and greater ones in ID when compared to post-war ones.
Surely, there's someone out there who has grappled with this conversion and has some information that they can share? Here's hoping.
Peter B
It seems from my discussions with 'A' enthusiasts, that the predominant 'A' system was originally "cup to cup"; ie 4 x F128 ground in a simple 'U' shape. I have a pair of worn ones on the desk in front of me. They are much reduced in height compared to a postwar pair with balls in place, moreover there are tiny differences in OD and greater ones in ID when compared to post-war ones.
Surely, there's someone out there who has grappled with this conversion and has some information that they can share? Here's hoping.
Peter B