[MaciekA]

There's definitely gear whine in your setup, but you don't get to hear much of it at 11.1V. It's possible that at some point you overtaxed your motor somehow, and now it's irreversibly pooched as Kos-Mos suggests. Perhaps your shimming is closer to a good state now than it was when you damaged your motor.

I recommend a couple things:

- listening to your shimming on a weak 7.4V so you can actually get a chance to hear what's happening. I use a 650mAh 2S from hobbyking just for this exact use.

- listen and adjust your shimming without the spring/piston/etc installed -- i.e. just with the gears in place (also take out the ARL so you aren't distracted by the noise that it makes). That way you can super fine-tune your bevel-pinion mesh to perfection. I always start with just the bevel during the audio test, weakest battery I have, and add gears from there.

I'm tempted to get a 3.7V LiPo just for testing shimming acoustics.