I have the same “problem” with my two 6384 sensored 170kv.
They are relatively quiet until a certain RPM, then they get really loud and go silent afterwards again. I have to check at which RPM this whining occurs. I’m using ESCapes in FOC btw.
My Motors also get really hot during riding, i dont know if there is a connection between these two issues…
They are mounted on a Mountainboard with an E-Toxx Gear drive.
I dont know how loud exactly, i do not have the equipment to measure it.
But they get around 4-5 times louder at the mentioned RPM, sounds like a angry turbine.
If it sounds like a “guitar string” (use your imagination, like a twang-y ish sound) it’s a loose motor winding. Pull the can off, grab a toothpick and find the loose wires, hit 'em with a dab of epoxy and get schwifty
It’s a strange issue, because that’s not really the sound it makes. It’s a much harsher grinding sound, but disassembly reveals no scratches (and I looked everywhere). The manufacturer tells me it is normal and will not damage the motor.
I’m away so won’t be able to for at least a week, but I think the vibration is along the axis of the shaft, not side to side, based on the slow motion video I took (again, saved on my desktop, so can’t post for a week)
Sounds similar to my issue, it only seems to happen in a certain RPM range, outside of that range the motor sounds perfectly fine. I haven’t had any issues with the motors getting hot though so that may be a separate issue?
The videos in this post are fairly similar to the sound that I’m getting from one of my motors though