I get that. The car is pretty neutral right now with some slight understeer. I'm fine with that. I am looking to build a similar car within a year or so and was thinking of having it a step or two softer. Again, it is easy enough to do with torsion bars and sway bars due to the diameters/lever arms but....
I used Direct Connection's "neutral handling" methodology to find my Swinger's needed rear leaf spring rate and its a decent starting point. You can do the same using your
current car as a starting point since its "
pretty neutral" handling is what you want to emulate only "
softer".
1) Calculate your current cars Front roll couple. That value will represent 75%-80% the cars total roll stiffness. Thus the 20%-25% remaining will be the range of your CURRENT car's rear roll couple. I'm guessing if you back calculate the leaf spring rate, your MP XHD may be in the range of 110-140 lb/in
2) Now substitute in "softer" TB redo the calcs and see what the rear leafs you'd need. Just error on the side of too soft because a rear bar can bridge the gap and bump up the rear roll couple.
