nothing to do with my mount, over kerbs,
any sudden bump in the track texture i get a rattley clack.
OK, I was unclear; the mount to which I referred is an adapter/hub between motor shaft and steering wheel. My AccuForce is DIY version (no motor housing),
with its motor shaft thru a hole in a solid wood plank to which it is bolted;
no vibration there..
DIY AccuForce does not include SimXperience's steering wheel hub,
and Ascher Racing's alternative adapter clamp became unavailable;
I temporarily employ a weak alternative.
An eBay steering wheel with neither paddle shifters nor button box
leaves basically nothing for the motor to rattle
except that weak hub clamp.
There are no rattles when that hub clamp is tight;
when a rattle develops, shimming and re-tightening the hub eliminates it.
If there is absolutely no slack in your wheel hub and quick release,
then rattles
may be sympathetic vibrations e.g. in shift paddles or button box.
For FFB amounts I can tolerate, no rattles from the motor itself are detected.