tsfarrell

Have shudder in main rotor of mSR. Checked all the linkages and used the alignment tool. Rotors are in perfect shape.How to balance? I can't see where the shudder originates from, but it clearly causes entire heli to vibrate and it is clear that the rotors arewhere this originates from.

Any sugugestions? I can trim to perfection, but this shudder just developed after a moderate crash.

ct420

Your main shaft might be bent. I would pull it out and check it. Also, check to make sure the flybar is not bent. I bent my flybar last night after a fairly mild crash...

tsfarrell

Thanks, those are great suggestions. A bent shaft would definitely cause imbalance. However, found and corrected a different source of the problem. I was preparing to disasemble, inspect and reassemble the entire rotor mechanism. First thing Idid was remove the servo rods, and it occured to me it would make sense at each step along the way to test as to whether the vibration was stil there. As it turned out, with no servo rods, the main rotor was again spinning properly with no vibration.

I'm not really sure what was up with the servo rods. Ihave had to lengthen and/or shorten them where it was otherwise impossible to trim using the remote. In some cases I have had to twist the plastic socket almost off the servo rod's screw threads. Also, at one point I inadvertently reinstalled one of these in front of rather than behind the perpendicular mounting rods just behind the 5-1 board. Upon examining the rods, I did find one slightly bent, so I bent it straight again. I guess I can see how, if one or both of the servo rods were binding it could pull the rotor axle to one side a bit and then create imbalance and vibration.

Anyway, upon reinstalling the servo rods, I verified that proper function without vibration had been restored to the main rotor and that flight was again steady without the shimmying Ihad observed before.

I'm glad this was not a difficult fix. I have already had to replace my rudder prop motor becauseI did not heed the warning people post on forums to use a thin piece of electrical tape to ensure the back o the motor does not pop off in a crash. $15!

Thanks again for your suggestions.