I had a motor make an awful screaming noise at a very specific speed. Turned out to be a crooked magnet. The retaining ring wasn’t pressed in all the way from the factory. Took it apart, cleaned it up, realigned the magnet, seated the retaining ring, and epoxied them in. Super quiet now.
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Yeah mine do that, 6384, it’s fine it seems
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So negative
The motors are perfectly fine - basically the best out there for the price, but like Jackson said, they occasionally have a set that scream
I’m guessing it’s a bearing thing
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Could be a higher voltage thing.
My TB 63100 165kv motors screeched real bad with my 18s battery after like 30mph.
12s, no problem at all. And they were the same exact motors.
I think @Skyart had the same problem too with 18s.
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I know the FS’s are known to do it on 12S as well, so I’m not sure it’s that. But interesting to know that could be a possibility
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I’m going to reach out to Flipsky about it and see what they have to say. They’ll probably blame me 
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190kv @12s reaches an RPM that makes the scarry resonance noise. It’s the reason I went with 170kv on 12s. Doesnt make a terrifying noise even at full unloaded speed.
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The speed at which the motor scream is probably the cans resonant frequency
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Exactly what I’m doing with mine. Sounds fine with 10s on 190kv. Got 170kv for the 12s proto.
This makes sense. Now I’m wondering how I might alter the variables involved with resonance in this case.
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Only thing I can think of is adding wieghts somehow and spinning them. Compare sound levels, trial and error 
EDIT
I found this 420 tape lol, its leaded and could work to counter balance the can
https://www.3m.com/3M/en_US/p/d/b40067913/
oh god its so expensive
https://www.digikey.com/en/products/detail/3m/420-1%2F2%22X36YD/1818913
Cheaper version that probably isnt as good, I bought some, ill see if I can make a difference in how loud Rocinante is
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I have access to a tire balancing machine at my father in laws mechanic shop but I need a chuck small enough to grab our size hubs. It points spins it and when it stops, a ring of lights pops up with red yellow green showing where the imbalance is.
Dammit we need an esk8 version
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Could a motor can fit in there?
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No but if one was made for smaller hubs it ought to 
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Maybe try to adjust the switching frequency on the VESC?
The now discontinued ARC200 controller made a big deal in their advertisements that “23.4kHz switching frequency for zero audible PWM noise”
Also this discussion
On vesc 6+ i can hear it faintly at 25khz and only on low battery at 30khz. It almost sounds like a wheel is slowly losing air so it’s quite odd
25Khz is quite a good frequency for the typical skate outrunner.
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This sounds very interesting. The switching frequency is set at 25kHz. I wonder if I should try turning it up or down.
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Let us know how that works!
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Looks like that FSEC 7550 uses 3 phase shunts, so you should be able to increase it quite a bit. Give 20 & 30 a try to see what noise it makes. You can also turn on “Sample in V0 and V7” at 20, 25, and 30 to see if it makes a difference.
Also:
Phase shunts do offer a benefit of doubling the sampling frequency which makes it easier to move into the inaudible range but we need to do some tricks before it’s possible to run 45 khz pwm sampling v0 and v7 without maxing out CPU.
Interested in the results!
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Heya, switching frequency won’t do shit for motors resonating. Switching frequency at 30khz mutes what i can only describe now as a fridge running sound, kinda.
As for the actual issue. I had freerchobby motors that were resonating at 28 and 31mph each, really fucking annoying as all london roads are mostly all 30mph. Solution?
Changed from freerchobby 190kv (10/47 with 9 inchers) to flipshit 140kv (12/47 9 inchers) and that resonating frequency is well above my max speed now. They run way cooler as well. Roughly in tune with heatsink exposed vescs, where shitchobby ones were at 85°
I was wrong about the switching frequency setting. The Ubox is actually set at 40kHz! I turned it down to 25 kHz and set “Sample in V0 and V7” to true. It does seem to have reduced the problem. It’s more of a whine than a blood curdling scream, and it doesn’t last as long. Before it lasted clear from 25-30mph. Now it seems to be right at 26 mph. I’ll do some more science, but I may owe Flipsky an apology.
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