Hello BD, There is a chart for gears in Albion 'boxes in Service Bulletin #1 (reprinted by Gene Shillingford and Sons of Philadelphia, Cooper Motors of L.A. in March 1963, and the REOC in a year end publication signed by Paul and Jane, if that helps identify an edition of The Gun for folks to get their own copies.) The closest match I can find is the "H" series of gears in the older gearboxes. These are finer toothed gears that were superseded by coarser "HG" gears around 1959 as engine power increased. The counts in the list are: mainshaft 18, 21/25, 30; and layshaft 30, 27, 23, 18. The simple, straight gears seem to lend themselves to varying the tooth counts. I acquired a collection of ex-dealer spares that includes many NOS gears with oddball counts. I have no information at hand on the gear counts in the unit construction 250 Crusader series, but expect you would find that on HMC's site.
Off your topic, I note your address and will be in Kirkcaldy from mid-August to early September. I am looking for RE and old bike connections, and hoping to find some trials events to watch.
Chris Overton, Rossland, BC, Canada [email protected]