Has anyone been successful modeling rolling contact in NX/Motion without significant numerical chatter? Are there examples anywhere? The attached pdf shows a very simple model of a "car" with 4 wheels. Changes to contact settings, friction, etc does not seem to settle the noise down. Force in the x-direction in the plot shown should be zero (constant).
At first glimpse, I would suggest to change the sphere geometry into cylinder instead, because the cylinder geometry has more geometry to possibly in-contact with the flat ground, thus help to reduce noise.
Furthermore, I think you can try to play around with the damping values in the 3D contact definition, which might help in your case.