Tail Shakes,side to side

[Ron S]

I changed out the belt in my heli last night. It was flying well,but after replacing the old belt with a new one,it now shakes really bad when spooling up. The tail rotor will start out turning smooth,then at around 1/4 throttle it will start shaking side to side. Then after advancing the throttle more it will quit? Then as you give it more throttle (around 3/4 ) it will start again. I can't figure this out. All I changed out was the belt,now the heli is doing really bad. Any ideas? Thanks Ron

[rockjock3]

Why did you replace it (crash, break, missing teeth, etc)?

Chances are you didn't get the tension right on the new belt (if you merely replaced it to replace it). If you replaced it for other reasons then there might be additional causes.

[Ron S]

My idler pully was stuck,and not turning. By the time I noticed it,my belt was about shot! I found the problem,with a little help from Finnless Bob:thumbup:. He said to turn the gain down,so I tried it and it worked. I'm still not sure why you would have to change the gain after installing a new belt,but I did,and it was the cure:)! Ron