Originally Posted by
1967brutus
Maybe a silly question, but... have you checked whether the bearing was a C3 clearnce class bearing?
Typically, standard (C2, usually not even marked as such) bearings have a slighly looser fit on the outer race, and a tighter fit on the inner race. These bearings will usually come out with the shaft.
C3 bearings usually fit a bit tighter in their seat (outer race) and a bit looser on the inner race, and will stay put while the shaft is pulled out.
Not a rule set in stone, and I have seen wallowed out bearing seats, but most engines that I fix for people, if the bearing comes out with the shaft, it is because it is not a C3 bearing, and fitting one usually solves the whole issue.
Brgds, Bert
Hi Bert,
The bearings installed was exact the same type as installed from the factory. A Standard (C2) bearing was fitted, so the same was used on replacement. I have noted that a standard (C2) bearing is also installed in my OS 48Surpass. On the other hand I see C3 bearings used the most on 2 cycle engines. Might have something to do with RPM and heat build up.
I was always of the impression that the C2/C3/C4 designation had to do with the internal clearances in the bearing and not the fit on the outer/inner ring, but I might be wrong for all I know.