Rear roll center question

[dontlifttoshift]

You are confusing the geometric roll center with a physical pivot point.



In the case above, the roll center is in the middle of the bar at that height, the distance from that up to the CG determines the leverage and how much weight will transfer from the inside to the outside. Regardless of suspension type, roll center is roll center and for a static comparison, the math stays the same.



Dynamically, in this picture with the PHB chassis mounted on the passenger side, in a left turn the roll center gets lower as that side of the PHB travels downward. In a right turn the RC gets higher. The fast kids can tell the difference on track.

Your floating and fixed terms muddy the waters significantly.

[Peter Mc Mahon]

Donny. Thanks for the reply and yes I am having issues wrapping my head around a difference between physical and geometric. In the illustration that you gave, where would the roll center be if the Panhard Bar was only 1/2 it’s length? Same mount on passenger side but mounted on the center of the differential? And, I have looked but can’t find a picture that demonstrates reference lines drawn to show why it is the roll center, any chance you can point me in the right direction? Thanks

[dontlifttoshift]

Donny. Thanks for the reply and yes I am having issues wrapping my head around a difference between physical and geometric. In the illustration that you gave, where would the roll center be if the Panhard Bar was only 1/2 it’s length? Same mount on passenger side but mounted on the center of the differential? And, I have looked but can’t find a picture that demonstrates reference lines drawn to show why it is the roll center, any chance you can point me in the right direction? Thanks

Roll center is still in the same place, with the PHB at half length. When I wrote above about it being in the middle of the bar, that was just coincidence and poorly worded on my part, it's in the middle of the car in that picture.

[Peter Mc Mahon]

Roll center is still in the same place, with the PHB at half length. When I wrote above about it being in the middle of the bar, that was just coincidence and poorly worded on my part, it's in the middle of the car in that picture.

I think Donny is saying the roll center is always in the middle of the car in this statement, and I think Rob is saying it is always in the center of the 2 pivot points of a panhard? That is what I meant by saying Rob and Donny are saying different things. Donny, Rob? Am I misinterpreting? Thanks again guys