Rear Main Bearings

[Bob Culver]

At least to the mid 50s with the oils of the time Sevens used for short runs developed significant corrosive wear of the roling bearings and the engines became rough and harsh. (Len Sothward of museum fame and one time Seven specialist told my father around 1940 that cars often presented with the flywheels rubbing! My father was somewhat fussy and used to replace the rear or all bearings every two years or so; the frequency of modern oil changes! At one period when he was very occupied with our new house and the engine deteriorated to the stage where the engine developed a sort of cyclic roughness. But I would not expect noticeable change in a few months on modern oils.  Is the race a firm fit on shaft?

I understand that rollers are selected to give correct clearance and that all within a bearing are and should be the same within incredible tolerance for acceptable life. If loose rollers had been extensively used mixed up rollers would have been inevitable in many circumstances. But from schoolboy bicycle days crowded races cf cages do appeal!

Am curious as to unfitted clearances of currently supplied bearings.