Gearbox Strange Problem

[Blackseven]

I've reassembled the gearbox mainshaft / input shaft / drive shaft (depending what you want to call it) - the one the clutch fits to!

Everything is assembled exactly as per the factory manual with the standard 1.6mm thrust washer. The manual factory just says to check that 5th gear rotates freely and if not, use a thinner thrust washer.

Mine rotates freely - in fact there is about 1mm of movement of the 5th and 2nd gears left to right along the shaft. You can see this play in the attached photo by the gap between the needle bearing and the circlip on the end of the shaft. Nothing on the shaft looks worn - certainly nothing like enough to give 1mm pf play if there isn't meant to be any!

It is almost as if there is a missing shim but I don't think there was one on the shaft when I disassembled it and the factory manual doesn't show one (second photo).

What has got me thinking though is that the Haynes manual does show a shim (third photo) part number 3 on the diagram.

Can anyone shed any light on this? Better still, have you got a complete, assembled shaft you could check and see if there is a similar gap between the needle bearing and end circlip ?

Thanks very much!!!

Rob

[z1bman]

there are only two sizes of shim & you say yours has got the thicker one of the two . the movement/ gap you have between the needle roller & the cir clip looks normal to me

[zed1015]

Yours is as normal.
No shim on the circlip side.

[Blackseven]

Thank you z1bman and zed1015.

It just looked odd having that much play in the whole assembly when the largest thrust washer is fitted. I cant imagine why a thinner one would ever be required unless there are massive differences in machining tolerances of the components which sounds unlikely.

Anyway, thanks again.

Rob

[johny brando]

Wow, that is a strange one......having that massive clearance ! I just checked my Clymer Manual & that shows the same as yours Haynes manual i.e ...there is a shim at the end of the shaft " before " the final Cir-clip . Have you checked that the toothed washer further down the shaft...( # 9 in your Kawasaki manual )..... thats in place aye ???.... as if that's missing, you'd have more gear end float on that end of the shaft . I'm sure as z1bman & zed1050 have stated that it's likely correct..... but for me personally I'd be concerned too, as to have 1mm lateral gear float seems an awful lot & weird . If the primary drive gear to the clutch was NOT a straight cut gear, then I'd say perhaps it doesn't matter as much.... because the main shaft / primary gear rotation would be permanently loading the shaft in one direction but this isn't the case ...because there a straight cut set of gears.
Perhaps you should re-assemble the complete gearbox in the open crankcase half & measure and note & see if the corresponding meshing gears on the Lay shaft would line up better, if the shimming was tweaked /adjusted to suit . Also measure & note the exact end float clearances you have there & then try & draw comparisons with other paired gears within the box ...see if others have a similar end float, if so , well maybe it's OK ...but if they don't... maybe try and get a part number & spec-thickness on that missing end shim of yours....if you can't get it or find out it's thickness you could make your own one up and leave say a 5 thou running clearance & placing it where gives the best meshing alinement . I don't know what else to suggest .
Hope what I've written hasn't caused any confusion ...only trying to help !!!! Good luck.

[Blackseven]

Thanks Johny, by coincidence, late last night I did try dropping the assembled shaft into the upper crankcase and once located on the set ring and pin at each end the play disappears and the shaft feels as it should.

When the manual refers to checking if 5th gear rotates freely and adjusting the thrust washer thickness to suit, they are obviously referring to when the shaft is located in the crankcase and not sat on the bench!

Obvious when I think about it now but it had me confused (not hard to do!) for a while.

Cheers, Rob

[zed1015]

The Haynes manual has used the early 72 factory manual for refererence which does show a shim between the circlip and bearing.
However in all manuals after that the shim is not listed so was obviously unnecessary.
Some early engines may have had the shim but i have never come across one with it fitted.
I have 8 gearclusters here from untouched 900 and 1000 bottom ends and all are the same as yours without the shim.

[z1bman]

once the clutch assembly is secured the shaft cannot move as the shaft is secured by the big roller bearing which is secured by a retainer in the crankcases & the clutch & gearbox shaft is sandwiched between this bearing

[johny brando]

Thanks Johny, by coincidence, late last night I did try dropping the assembled shaft into the upper crankcase and once located on the set ring and pin at each end the play disappears and the shaft feels as it should.

When the manual refers to checking if 5th gear rotates freely and adjusting the thrust washer thickness to suit, they are obviously referring to when the shaft is located in the crankcase and not sat on the bench!

Obvious when I think about it now but it had me confused (not hard to do!) for a while.

Cheers, Rob

Aaah thats great..........glad it all came out in the wash & it's always better be sure when you have the cases apart ....as it's real annoying to have to rip out & apart 2 days down the track.