Having followed the ball vs roller main bearing debate with interest, I'd like to ask those in the know about 7 vs 8 balls imperial size ones. I tend to hang on to used bearings for some reason, two of the ball main bearings in my treasure trove sports 8 balls. The bearings supplied by my dealer always have 7. They seem to wear well enough, but do the 8 ball variety have a higher load rating? Are they available today?
Had a quick look in my bearings drawer and the 7 ball variety are Skefko, Hoffman, SKF, Fafnir, NSK and FBC. 8 ball bearings are RHP, R&M and FAG. All came out of Triumph engines. Most are marked with 3 dots, some not marked at all. I presume unmarked are CN?
8 balls will have more contact points at any given time, thus an increased load rating. The balls are smaller too, which means less difference between inner and outer track diameter, and therefore less skidding motion between balls and tracks. As I understand it this should give less wear at higher rpm, and therefore a higher rpm rating. Is this correct?
I'll make sure to specify RHP mains next time I order. Sometimes more IS better.