Bob
The car is an 1800 lb 100 inch wheel base street roadster. The engine is set back 10 inches. The weight is distributed 43% front 57% rear. The tube front axle is located by 30 inch long wishbones and a 24 inch long 5 leaf transverse spring with 2 inch shackles. The wishbones are parallel to the ground and the 30 inch long drag link. There are provisions for a pannard rod but pulling side ways on the chassis shows little movement from the shackles. I know that the combination of tube axles and wishbones binds on one wheel bump but the suspension travel is one inch. The good side to this is that it increases the roll resistance at the front. The CG at the front is approximately 17 inches off the ground at the rear it is about 20 inches. The tires are 24.5 inches OD front and 28.5 inches rear. The track widths are 55 inches front and 56 inches rear.
I would like to keep the roll to less than an inch so the tires can be close to the fenders. I can put a spring scale on the roll hoop and see how much force it takes to roll it. Given the manufactures chart of stiffness for a given bar and arm length I should be able to do the geometry and math to calculate the desired moment.
Dave's comment about the antiquity of the design is of course correct. I know that the front roll stiffness should be greater than the rear to avoid over steer. That being said, for a vehicle designed to go in a straight line on a relatively smooth surface, the anti squat, anti dive, toe change on bump and all the other sundry adjustments required for getting the right amount of under steer for a driver to produce the quickest lap times are moot. I will again look at the possibility of putting the bar on the front however there is extremely limited space available and I don't want any of it to hang out in the air turbulence.
Thanks for your time,
Jim