Alright, this ones kinda long --
With the chain slack and the finger indicator on the sleeve gear (as pictured below) I tensioned the chain (with the bike on it’s wheels) just until dial movement -- then I tightened down the rear wheel and zeroed the indicator.
Sitting on the bike (at 160 pounds) I got a reading of .014.
Bouncing a little (though, not nearly producing the typical swingarm movement/ oscillation of riding) my girlfriend saw the needle hit, at it’s highest, around .026.
So this is an effect the final drive chain has on the sleeve gear -- and to put this aftward motion in perspective, the wall of the bushing replacements are .044, so that sleeve gear wants to move more than half the wall thickness.
My main shaft is fine. I put a dial indicator on it. And the sleeve gear and its bearing are fine (meaning, solidly located/ no discernible play) -- which is to say, this deflection is through a normal tensioning.
But draw your own conclusions as to what kind of effect this may have.
What I know is that my transmission case was FULL of bearing remnants that absolutely weren’t there when I just replaced the kick start shaft and the first gear layshaft bearing (…what minimal amount of “gold” I did find, I cleaned out).
This time, there was piles of it in every recess/ bearing -- even filling up the bottom of the gearshift detent bolt. “Dust” and shards. Everywhere.
My feeling is that the situation I described above is what largely contributed to the failure.
Before I put on the softer shocks I'd tensioned the final drive chain, and it was tight. "Too tight", but I left it. The chain is on the way out, and I’d been chasing the slack for a little while -- and that’s why I left it (as motorcycle chains, past a tipping point, just get exponentially looser). Yes: stupid-ish -- but I’ve clearly done stuff like this before and gotten away with it. I think, however, the real problem developed when I went to softer shocks and left the chain on the tight side… not thinking about it, actually. And I think I just rapidly wore through/ crushed the bushes.
This is my running theory, anyway.
