@jracer
Hey,
The rear geometry is emulating a 0-degree sweep angle pure trailing arm. That's why the lower arms are quite long. There's 0 camber and 0 toe change on deflection, and the roll center is basically at ground level like IRL.
I think the biggest inaccuracy is that IRL in roll and in 2 wheel bump, the roll center should not move at all.
I never graphed it out for this one specifically but I'm not surprised if the roll center moves a little on deflection. I can't see it at all in the car handling so it's probably not significant. My semi-trailing arms however *did* have pretty reasonable RC migration in 2 wheel bump and roll when a friend of mine graphed them out, not enough to cause error, so maybe this one is good as well. It is all about the acceptable level of accuracy after all; we don't *really* have trailing arms in AC so you must settle for some compromise.
In un-symmetric wheel movement, like a roll where one wheel moves more than the other, I believe the error is somewhat higher. That is because in DWB suspensions the roll center is determined differently than in a trailing arm suspension. The DWB suspension cars about the angle of the arms, while the trailing arm suspension cares about the angle of the *links* on the car body. So no matter what the wheels are doing, it will still only reference it from the car body angle, not the arms' angle. That's my understanding at least.
That probably means there is some error in a dynamic roll situation, like when the outside hits the packers but the inside does not, and there is unequal roll. Does it matter? I don't know, the car handles very well to me and the wheels and body is controlled as I would expect.
I had some fears that there would be significant error in one-wheel-bump from having the arms cross over so far, which means that the left side now should interact more with the right side and vice versa, because when the opposite wheel moves the opposite chassis, it affects the link of the wheel that is not moving.
I did some testing between normal arm lengths and the very long ones and I at least could not find anything of note. The jacking of the body is exactly the same between them and the wheels stay controlled, so either due to my lack of understanding I am missing something, or it is not so significant at all.
You can decide if it is undrivable, inaccurate and broken or not.
