CB72 - How does oil get to the rollers on the Countershaft ?

[Phil-UK]

Hi

All numbers refer to the Transmission page in the parts book.

I've just been shimming up the gearbox on my CB72 and on the countershaft the dogs between 2nd ( #9 ) and Low gear ( #7 ) were not fully engaging so I have put a copper washer around the outer face of the 14mm bushing ( #1 ) so that it bears against the face of the 21T countershaft ( #6 ) at the end where the 5x6.25 rollers are. This has the effect of bring the dogs between #9 and #7 closer together when selected.

At first the washer was too thick and the shaft was binding so I ground down the face of it until the shaft would spin easily. The dogs now engage more fully and I can select the gears by rotating the selector drum by hand whilst spinning the mainshaft ... all well and good.

However, I am now wondering if the box requires some axial play in this area so oil can find its way inside the 21T shaft to lubricate the rollers; does anyone know how these are lubricated ? Is it just splash getting in there or have Honda designed in clearances which I have now closed up ?

I can split the cases ( only the bottom end together so far ) and take some more off the copper washer if necessary.

Any suggestions ?

thanks

Phil

[G-Man]

Phil

Do you really mean a copper washer? Bronze would be a better material for a bearing surface.

You could cut some rounded slots in the washer to let a little oil in/out. Thrust washers usually have some grooves in the face to distribute oil.

G

[Phil-UK]

Hi Graham

Yes it is copper as I couldn't get anything near enough size wise in steel or bronze and I think I've read of others using copper in a similar situation.
Good point about thrust washers having "slots"; I suppose the proper way to do it would be to make up a new longer bushing to take up some of the play or make a shim/washer in steel to take up all the play but with slots in to let oil throught - I'm afraid my skills sren't up to that.

Will see if anyone else has any thoughts and then decide what to do, if anything needs changing then I do have a spare bush to take measurements from.

thanks

Phil

[G-Man]

Phil

Copper is definitely not a good bearing material. Bronze or hardened steel would be better. If you could sketch what you need I may be able to help you.

G