|
Roll centre is a well discussed subject and surrounded by a lot opinions.
Accordingly I hav an opinion of my own here. The weight transfer is (w*g*cgh)/Tw no matter the height of the Rc. If the cgh is 400 mm and the Rc is 200 mm the car could be said to have 50% antiroll. 50 % of the moment over the 400 mm arm is going throught the springs of the car and 50% is geometrically going directley to the ground.
This antiroll force is very brute to the tire grip and destoys grip, as it makes the car partley "sidway unsprung". If rising the Rc at one end of the car this will have a similar effect as mounting a stiffer rolbar at that end. The difference is that the part of the Wt that goes over antiroll is totally ded weight transfer. (Eexept for the tires). It is better to use an heavier roll bar that also make use of the shock absorbers to dampen the moments of roll, making the weight transfer more controllable.
So, I suggest using close to ground Rc at both ends of the car, and A-arm geometry tha keeps the Rc at the same level during wheel travel.
If Rc alters even the over-underster of the car will alter during wheeltravel in a corner. What we have to lok for is where the forceline intercept with the middle vertical line under Cgh of the car, or should we say the angle of the forceline should be keep constant during wheel travel. Where the left and right forceline intercept dosen matter at all, the car is having its real "hinger" Rc in the midlle of the car anyway. Also, it is the outer loaded side forceline that carry the moost of the weight anyway.
Goran Malmberg
|