Hi, looking to order some new bearings to replace the rears, I can’t make out if the old ones at C3 or not, does anyone know?
SKF recommend non C3 for motorcycle wheel bearings so unless manufacturer specified I wouldn't use them. They will be looser and wear quicker. Cam Tensioner SKF bearings are C3, the clutch bearing is not as it rotates at half the speed and runs cooler so my first thoughts were non C3 but a google uncovered the above info.
Dunno - but they use SKF, looking at the specs they should be non C3 which are tighter tolerance...……….. ...just had a look at some hub bearings still in the Ducati Blister and they are non C3
Stu, I was always told not to fit tighter clearance bearings than the OEM fitment if the bearing will warm up due to speed or extended running, or if the bearing gets pressed into an interference fit hub for example. In use the clearance disappears as the bearing gets to its operating temp, tighter tolerances means less room for a little expansion effectively generating a preload which can lead to premature failure. In other words tighter clearances is not necessarily a good thing. That was nearly 40 years ago however. I think the OEM spec is C3 as suggested above
Lets see what Nelly says - my hub bearings still in the shrink wrap aren't C3. I have come across Ducati using different spec bearings before which is why I knew about the Clutch Bearing being wrong as C3. And as above, info suggests SKF do not recommend C3 for motorcycle wheel bearings (found this on a Kawasaki forum re ZX10R's I think it was).
From Simply Bearings Web Site: Question "What are C2, C3, C4 and C5 bearings?" Answer C3, C4 and C5 bearings are bearings that have an additional internal radial clearance to cope with high speed environments where excess heat is generated. They are not suited to environments where critical alignment is required from the onset e.g. Where blades and cutters are set up to each other. Applications like motorcycle wheels or bicycle wheels do not require C3 rated bearings. Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing, C3 Bearings are loose to the feel from new and often people complain at the quality of the bearing being poor and having more movement than the one they are replacing. C4 and C5 are even looser still than C3 clearance bearings. This is the characteristic of these higher than normal clearance bearings marked C3, C4 and C5. C2 marked bearings have less clearance internally than standard bearings and should only be used in applications that specify C2 clearance.
OK, but here is the packaging for the part number that supersedes 751622566 which are the front wheel bearings for my 748 (that I bought yesterday)
I think the part number change may correspond with a supplier change, the old part number appears to be non C3 so it could be a supplier spec difference
So, after a good scrub (the bearings not me) I can just make out a C3 so order changed to C3 bearings
