I’m assuming you are using FOC since you have vesc 6? screen dump after you run R/L/ flux linkage calibration. What is motor kV supposed to be? We could take a look at flux linkage measurement and compare it to your motor kV. If this value is wrong it could cause estimator to track poorly.
A screen recording of the realtime data screens while this phenomenon happens could also help. FOC tab might be most useful to see how FOC currents are tracking.
I might also suggest tuning the current controller time constant of your motor controller. I think by default it is 1000 us, try something like 2000-3000 us for less aggressive current controller gains.
Try BLDC also… if same phenomenon happens in FOC and BLDC, it is probably a mechanical issue with the motor.
Does this happen in a single motor configuration with each motor? How about without the gears attached, just bare motor?
Also what others said, about trying it in BLDC mode, but try without sensors (is it sensored?). The idea is to see if the vibration happens with these different methods to rule out ESC issue.
Although it seems highly improbable that both motors have the same mechanical issue.
That let me to the conclusion that it must be an mechanical balancing fault.
I tried balancing with different object just to try if it made any difference at all - No diffenrence
Back to VESC6 Settings - Autodetect settings ends up like this:
RPM Video of the problem (Motor goes up to certain RPM level and then vibrates even harder if i turn up the trottle, until it “breaks through” and gets above the vibration RPM zone: https://youtu.be/6_BeUVZet9A
I know I also thought that was the problem, so i took all magnets out today and 3d printet a guide for the other end (they are only guide at one side originally) and re-fixed all magnets totally aligned… And tada!!! No changes at all
Both motors are doing this at the exact same rpm range, with different vesc?
It seems highly unlikely that 2 motors would have the same exact mechanical defect and that both vesc would have same issue. So at this point perhaps they are incompatible
I would say if bldc and foc both produce this resonance, it is probably a poorly designed motor? At some speeds motors can have mechanical resonance but ultimatley should be designed with resonance peaks far from the operating range.
I also thought that was the problem, so i took all magnets out today and 3d printet a guide for the other end (they are only guide at one side originally) and re-fixed all magnets totally aligned… And tada!!! No changes at all 
