Jeez Dave,

I've got a ton of respect for your experience but what you wrote makes me go hmmmmmmmm......

With an engineering background and working for a company that makes/designs/tests transmissions I struggle to understand how there would be enough thermal expansion with the limited motion a gear sees in a servo under typical use. This would especially apply to jets where the actual servo movements in normal flight are so small and there's no vibration to generate load the same way you would see with a gas powered model. Also, while I realize that most jets servos are mounted inside the wing out of the airflow, the air velocity should provide some cooling to the gear train. Is there that much heat generated by the motor and electronics that would make its way into the gear train?

What I did find with not just JR but other brands of servos was the gear slop present did not come from backlash in the gears as much as the bushings for the gear posts were "egg shaped " allowing the post/pin to rock from side to side as the loads on the servo reversed. Why the servos have such small diameter posts/pins to support the gears is beyond me. Yes, I know that some servos have metal bushings to support the pins but even these will oval out over time.

I do agree that I have never seen flutter caused by slop in the gear train of a JR servo and there are so many other areas on an airframe that could flex and cause problems with the most common problem being just plain poor installation techniques.

PaulD