Something Failed, let’s find it! Transmission Analysis.


Something like this would be the $hit. Takes all the load off the snap ring. It would take up more room so would have had to be in the original design.

 
I found this write up, while it’s for an old model H2 trans, the principles should be the same:

Motometal Manual

Just from handling the output shaft I know for sure there’s at least 2mm between the 3rd circlip and the gear when it’s all shoved over against the circlip for 4th. Way too much space.
 

Hell, it sounds like there is already room for the center snap ring, just need the groove cut now.
 
Well here’s an interesting development....

Part #35 in the trans fiche is a splined washer that’s supposed to ride between the splined bushes and the 3rd 4th circlips.

GUESS WHOS TRANSMISSION DOESNT HAVE ANY #35s in it!!

Wondering if they’re omitted intentionally when the billet forth goes on at Robinson now?
 
Good forensics Rob...i will check mine when I'm next inside...won't be for a couple of weeks
 
I'm pretty sure I can't help here, but I've been encountering missing parts during my camshaft project, and just sadly is consistent with all bikes on which I've worked where a dealer tech touched it beforehand. Almost as universal as the bear $hits in the woods and the Pope is Catholic, if a dealer tech presumes that a part will be out of sight when the bike is buttoned up, parts *will* be left out.
 

They made some changes early on. Early gearboxes had a bushing and splined washers, later had splined bushings.

Early

Late