Hiya, just swapping my 31/9 to a 37/11 final drive (complete unit). Inspection and seals replacement, plus pinion bearing that had the (outer) inner race on a shelf for years that is rusty. Gears and all other bearings are in good condition.
Since buying the bike 3 years ago, I've done quite a bit of replacement and Youtube has been very handy. The shouty guy who swears a lot, another chap in Finland I think and the very personable Boxer2Valve. I just watched his vid on rebuilding a final drive as I am doing that now. His process, method and measurement for bearing change in a final drive assembly is quite satisfactory. Likewise what he's done with Bing rebuilds, front wheel bearings etc.
The internet is obviously open to abuse and alternative or just misinformed advice and information. I don't believe that is the case here.
I think if assembling a new (or new to this box) gear set in a particular box would need more setup to be correct (blueing the gears and checking the mesh etc) but for a worn set in the box it came in and was originally set up for - that seems to be going a bit far. Gears with 30,000, 60,000, 100,000? miles on them are not going to set-up in the same way as a new set and by definition are not going to last as long. A good approximation IS going to be good enough.
What exactly is he doing incorrectly? (before I nail the FD cover back on
)
[Apologies, this is a diferent (and technically much easier) question to the OP, but on the same theme. I'm using all the same internals apart from the input ball bearing and have a conventional (full axle, dual shock) all-steel crownwheel assembly].