Ed,

I believe you are correct about the source of the squealing sound. I can reproduce the sound and effect by hand spinning the clutch bell on the engine, with the engine removed from the heli. It is defiantly the clutch bell vibrating.

I do not think that greasing the shaft is a long term solution. I found that either grease or oil would get rid of the squeal, but only for a few tanks of fuel. After a few tanks, the dripping goop pretty much washed out all of my grease and oil.

I also do not think this is a problem due to your worn parts. I was able to get the vibration to happen with all brand new parts, all old parts, and a mixture of new and old parts. This includes new/old clutch bells, new/old clutch shafts, new/old washers, new/old clutch shoes.

I do not know if vertical play in the clutch bell has an effect on the squealing or not. I attempt to set the bell up with as little vertical play as possible while still being able to freely turn. As such I can not practically experiment with less vertical play, and using more vertical play seems to make getting the mesh with the (always wobbly) main spur gear even more difficult.

In short I have no solution for this. I also suspected my fuel, but reproduced the effect using several different fuels. Keep me posted if you find a solution that works.

For what it is worth,
Spiro

ps: for all those who might be interested:
http://www.rcuniverse.com/showthread...96&forumid=192]