T80 Crown Wheel early problems

hi Guys

Just an interesting comment which was made to me after I finished the 140mile Eskdale Run on Sunday 2nd September.
A gent announce himself as once being a mechanic in a Yamaha dealership when my model came out in the early 80's and that very early models suffered from a batch of faulty crown wheels which resulted in a recall and a change in lubrication  specification etc.
Interestingly when I bought my 1985 bike last year with only 12k miles on it I found the crown wheel extremely worn with the teeth barely 1/16 th of an inch thick at the periphery when they should be twice that thickness at least.
makes you think that the odd one may be still around?
such is life  

I overhauled my final drive last year. The bike is a 1985 model with about 6k miles on the clock. The grease in the final drive casing was incredibly thick but the gears themselves looked OK once I cleaned them up. I thoroughly de-greased and replaced with the recommended amount of Spherol. So far seems OK.

hi andrwp  

Why the crown wheel on my bike happened to be that worn is one of lifes mysteries ? Obviously the PO must have known about the problem, filled it up to the gunnels with red grease and sold it on the internet?
My friend who never rode it, bought it, never did use it, and put it in storage. I stumbled across it by chance.
The noise from it on the overrun caused me to investigate after my first test run since purchase.
The bike is in such good original order deepens the mystery, but it goes fine now.
Even the original pinion was not in good shape, so just changing the crown wheel was not a sensible option.
it's a funny old world?