YingYuYang, I’ve got the same issue.
I once saw a cross section of the simucube posted somewhere and I’ve not been able to find the picture since, but the picture I saw showed the copper coils of wire just sort of layered at an angle going around the wheelbase - In most motor designs the copper coils are wound tightly around something, but these appeared to be loose, open air coils. My suspicion is that strong sudden changes in force cause these coils to move a little bit and they hit the coil next to them, and this happens in a circular way, so what I think we’re hearing is a bunch of those coils hitting in succession, rather than all at once. To me it sounds a bit like that childrens toy we call a “Slinky” here in the US.
The things I’ve found so far that help with the noise:
Set the slew rate to 0.1 <- this seems to work in conjunction with any other setting.
Set the smoothing filter to 10 <- I just tried this recently and it made the unit quieter, but I did not try all combinations with other settings.
There’s one thing I’ve not tried yet that might also prove my hypotheses - turning the Torque WAY Down - I’ve been running in the 12nm range, and if my understanding is correct, it takes both a sudden change in direction PLUS a decent amount of force - so setting the unit lower might also help - I’ll try that the next time I use the wheel.
As a side note, you can hear this sound anytime you want - you don’t even need to be in a game - just open true drive and have a hard stop set then rotate the wheel until you hit the stop - you’ll notice that if you hit the stop with enough force, you’ll hear the same sound you hear in game and it will be quite easy to recreate the sound to demonstrate it.