Sway Bar Help???

[Norm Peterson]

well they say not to run a front bar that is bigger than 1 1/8 and that the 1 1/4 bar is too big. thought that was kinda a stretch, because of that little bit 1/8. The other thing is they said, with thier springs a rear sway bar is not nessicary, do you believe that?

I did find that the 1.125" bar recommendation is made relative to the use of their springs and the negative roll system. If you only look at the front suspension, it does make some sense to limit how much roll stiffness you build in to it, since the higher RC is already drawing more of the LLTD forward.

But the front suspension does not work in a vacuum, and the avoidance of a rear bar sounds more like somebody's personal approach to tuning. It may be better in some cases to follow that path. For example, a low CG height car with stiff springs (think conventionally sprung Cup cars, not BBSS cars or the COT). But this is not a universal solution, and I don't think it's nearly as applicable to a relatively tall and at best moderately sprung street-legal car.

There is some merit in keeping the sta-bar stiffness from getting way out of hand relative to the spring stiffnesses and their contribution to roll stiffness. But that's only one consideration, and I highly doubt that the 52% increase in bar stiffness that comes when you swap out that 1.125" bar for a 1.25" bar crosses any make-or-break point. In fact, moving up from a 1.125" front bar to a 1.25" front bar and adding an 0.875" rear bar (LCA attached) leaves you with just about the same TLLTD balance and is essentially what GM did for the F41 Sport Suspension package on the '78 - '87 A/G bodies vs the base suspension. The payoff is about 20% less roll per lateral g and the associated benefits in reduced camber loss and roll steer.

It could be that the intent is to actively not control roll as tightly as possible. Roll itself is viewed by some as providing a subconscious warning to the driver. Whether that's necessary or even useful in a car that's being modified for the specific goal of improved cornering potential is a separate question.


Norm