Apologies for resurrecting this thread, but I have to reply to phat one more time.
I hope you at least read this. You will learn a thing or two about physics.
I never said the paper is handwaving, I said your arguments are. And did you actually read the paper and its graphs? You are quoting qualitative statements and completely ignoring the quantitative analysis. You have absolutely no idea what "increased ride stiffness" means in terms of body movement and are just assuming it's a big impact.
The paper does not contradict everything I said, and in fact supports it. I will use this paper you linked to show you how wrong you are about the impact of unsprung mass.
In this graph you can see how 1.5x the unsprung mass changes the local minimum in the phase angle from 7Hz to 8Hz.
Very low sensitivity to unsprung mass, just as I said earlier, and this is just a few degrees of phase angle. For any visually perceptible metric, unsprung mass has even less of an effect.
Okay, so you see a large frame to frame displacement with wheel contact. A half cycle per frame corresponds to a frequency of 30Hz.
"Adhesion is the minimum percentage of remnant vertical tire contact force between the tire and the road surface during vertical oscillation of the wheel. This percentage is calculated by taking the ratio of the minimum remnant vertical load to the static weight (vertical tire contact force) on the suspension tester."
So at 25Hz, there is still 75% adhesion. For you to see a gap between the tire and the road in the replay, you'd need 0% adhesion on the graph. Not only are you way off on your assertion, but the unsprung mass has little effect (and it's in the opposite direction anyway) on adhesion at this frequency.
Only at the lower frequencies do you see a difference, but it's a horizontal squeezing. The heavier unsprung mass has slightly less adhesion at 9Hz, but slightly more at 13Hz. The only way unsprung mass will make the wheels come off the track is if the dampers are completely shot, as I
mentioned before and is illustrated in
this graph.
So whether it is the analysis of the paper in your link or the math that I tried to explain to you, unsprung mass has almost no visually perceptible effect on wheel or body motion.
I know first hand it sucks to be wrong. Even Chalnoth, who is a physics major learning some pretty advanced stuff, messed up some basic Newtonian mechanics in a thread about cars and torque. However, try to learn something here. Subjective/intuitive physics (e.g. zero unsprung mass = perfect contact, non-zero mass = visual separation) are never guaranteed regardless of how correct and obvious it seems. Only when you do the math or analyze a simulation will you truly understand what's going on.
