What I was talking about is the leverage of the suspension of one end over the other (Front vs Rear). The
chassis moves about the roll center. If the roll center is at ground level, at one end and is at 12" at the other end,
can you tell us how roll couple works?
The topic of vehicle dynamics was studied at GM during the 1920's by Maurice Olley and later by Bill Milliken who authored an excellent textbook on the subject.
And who had forgotten much more than we have ever learned.
The front and rear suspensions each have their roll centers. Typically, the front roll center is below ground and
the rear about axle height. A longitudinal centerline is drawn connecting the roll centers forming a roll axis.
The distance from the sprung weight gravity center height (at the longitudinal center of gravity) from the roll axis, determines a moment arm. This moment distance times lateral G force will determine the lateral body weight
transfer acting on the springs.
The resistance of the springs (and sway bar) will determine the amount of body roll. Roll couple distribution is determined by combining the front axle spring rates (including bar) with the rear axle spring rates (including
bar) and dividing the front rate by the total rate. i.e. 1400 front, 600 rear = 2000 total. 1400 / 2000 = .70.
Since 70% of the roll resisting spring force is at the front, we say the roll couple distribution is 70%.
But weight transfer is another matter and does not involve roll centers.
Using a vehicle with front corner weights of 900lbs and rear corner weight of 600lbs, a 100in wheelbase, a 20in CGH,
and an accelerating force of 0.60g, the front corners weights will be 720lbs and the rear corner weights will be 780lb.
Which means that a total of 1560lbs of force can be transferred to the road surface. Try for more and the tires will spin.
That is for a vehicle with laterally balanced weight distribution. But in the real world, weights often are not balanced side to side. If LF=1100, RF =750, LR=650, and RR= 500, then with 0.60g, our corner weights become: LF=920, RF=570, LR=830, and RR=680. The left rear tire has gained traction but the right rear tire has lost grip and will spin earlier.
Using data collection, we have often observed a drag vehicle assume an angled attitude as it goes down the track.
Crabbing costs power, affects aero (drag and downforce), and can make the vehicle harder to drive. Be careful when
you lift off the throttle.