gearbox shim

[monument7]

Curious to know what exactly the shim at the bottom of the Christmas tree does.
I am swapping the internals from an LI150 series 2 into a series 3 casing and found that there was no shim under the Christmas tree on the S2. First time I've done this so bear with me.
Looking at the set up the Christmas tree sits in the case in a roller bearing and is then bolted through the endplate which stops any in and out movement so what is the use of the bottom shim.
If it's too thick it will bind between shaft and bearing outer and if it's too thin it will rattle and as there is an undercut on the Christmas tree shaft between the bearing dia and the gear the shim would move laterally as well.
I can only assume it is there to stop momentary movement during gear changes.
Can I leave it out ?
Cheers
Dave
P.S float on this is 0.8mm when the endplate is fitted without clutch but tightens to 0 when clutch is fitted

[monument7]

Anyone ?

[Warkton Tornado No.1]

Hi.

This is a subject that I have discussed at race events.

Because it becomes an issue if you make your own c/r gearbox (if welded & the fillet is anywhere near the spigot undercut) I have had little option but to leave the shim out.

The reason Innocenti fitted them is to serve the purposes of locating the needle bearing where it should be by controlling axial displacement in addition to supplying a thrust face that is, ultimately, sacrificial, rather than wearing the cluster itself. If it were a plain bush bearing, there would be no issue, but, the needle roller bearing cage will have a differing RPM to the cluster itself.

I hope to have helped & not been too technical.

Kind Regards

[monument7]

Thanks for the reply and certainly not too technical ( I've been an engineer for 46yrs ) and it puts my mind at rest now that I've left it out and as the needle bearing is enclosed top and bottom in a cage I can't see there being an issue with it wearing the cluster but now I've just said that I suppose the needle bearing would rest on the spacer as long as the spacer is floating slightly. Now I'm back to doubting leaving it out ha ha.
I'll just kid myself I've welded the cluster and couldn't get the shim in and maybe it will go away.
Cheers

[Wack]

You don't fit one with the Cyclone 5 speed

[HxPaul]

I had an Indian remade Li 150 gearbox and when I fit the cluster with the shim it wouldn't move,I had to remove the shim to let it spin.

[rossclark]

I had an Indian remade Li 150 gearbox and when I fit the cluster with the shim it wouldn't move,I had to remove the shim to let it spin.

Had you fitted the clutch centre and torqued it up?

That can be enough to free up a stuck cluster.

[HxPaul]

I had an Indian remade Li 150 gearbox and when I fit the cluster with the shim it wouldn't move,I had to remove the shim to let it spin.

Had you fitted the clutch centre and torqued it up?

That can be enough to free up a stuck cluster.

Yes,clutch fitted and endplate fastened and torqued up.When I removed the shim and rebuilt the gearbox/endplate and clutch everything felt free and was easy to move.