GY6 transmission noise/final shaft play.
 

Based on ckau's comment about the whine he heard in the video, i opened up the transmission end of it today. The gear oil was showing its age with a decidedly dark brown tint along with very, very fine grey particles. I'm not too concerned with the "grey matter" as there were no chunks, flakes etc, looked like a pretty normal amount for gear oil that has had probably a lot of run time on it.

The gears themselves look fine, no unusual patterns on the teeth no nicks, cuts, grooves etc. The carrier bearings in the outer case halve gave no evidence of play, On the inner half of the case, the lower "dual gear" has a tiny bit.

The output shaft on the other hand seems to have a lot of play, can't tell if it's the shaft or bearing or both.

For those who've worked on these, with it fully assembled and the reverse gear on, should there be any visible rocking/off center movement of the output shaft? I'm thinking it's starting to work on an angle against the next gear during higher rpm/loading

When i posted my engine test videos, i showed a few seconds of the drive sprocket's wobble.

I'm thinking i should leave the transmission gears and bearing be and just pop for a new output shaft, bearing and seal.

Thoughts?
TIA

the gear whine is clearly audible at the higher speeds in the second "run" in the vid ....

http://www.youtube.com/watch?v=IQ5OE6h6aW0

at 50-55 seconds, you can see the sprocket and entire reverse unit moving around. the gear whine is a bit harder to hear in this video.

http://www.youtube.com/watch?v=KcccZ0LHoLs

Normal ? Thoughts??
TIA

Talked about it with Tom/SYC yesterday, and after inspecting the gears and bearings several times, i've come to the conclusion that a new final shaft and bearing for it should suffice. That's the one thing about buying a used engine, you have no idea how much run time, what condition the parts are in or how the PO treated it. As ckau noted, if i'd run this much, the final shaft bearing probably would have kept degrading until the shaft hit enough of an angle to lock up the gears and the whole tranny section go kablammo like his did.