Clutch hub bearing

Madnorton said:

I'll assume that the majority of all current owners do exactly that.

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Well, then, I guess I'd better scrutinize the parts more.

There are a few possible causes for clutch wobble.
When rebuilding a gear box, I first assemble the relevant parts on a lathe: main shaft, then add clutch centre, basket, and finally complete clutch. On each step checking for running true.

ludwig said:

There are a few possible causes for clutch wobble.
When rebuilding a gear box, I first assemble the relevant parts on a lathe: main shaft, then add clutch centre, basket, and finally complete clutch. On each step checking for running true.

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True.
Hub fit on splined mainshaft, bearing I.D. onto hub, bearing O.D. into basket, mainshaft runout relative to sleeve gear bushes, sleeve gear runout, and also the clutch hub bearing.
Years ago, Dude Wheeler sold me a bearing for the hub, and he said it was a "special bearing". I respected his vast experience. That caused me to research in-depth WHY he had mentioned that. Coupled with my general knowledge of precision machinery, it was crystal clear why it is a "special bearing".

To minimize runout. All the aforementioned clearances stack up, so, it was decided to not "give away" any by using a loose fit bearing.

Just because the loose fit bearing assembles, and the bike can ride down the road, does not confirm it's fit for purpose.

ILLF8ED said:

C2 is closer or tighter tolerance. With 6007 the clutch basket wobbles. From experience.

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Yes it does.

L.A.B. said:

The factory manual.

"One dot bearing" = C2.

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Dot markings are still used on precision bearings.

Taking into consideration both shaft and hub machining tolerances, I would think that the bearing clearance needed would be unique in each configuration. We are talking about difficult-to-measure microns here.Why not trial fit each bearing designation (C?) to find which one is suitable? Maybe with a big rotating cantilevered lump it doesn't really matter that much as long as the races stay put.

I would not be shocked to find that the manufacturers in the 70s tried to make all bearing identical. Then tested and assigned the clearance.

For instance, Intel and Zilog freely admitted that about the 8080 and Z80 computer processors back then. If an early Z80 passed testing at 4mhz, it was marked as 4mhz. If not it was tested at 2.5mhz. If it passed it was marked if it failed it was thrown away. Later as technology got better the testing started at 8mHz (if I remember right) and stepped down from there.