Hi, as an oval racer and FSAE alum I have been curious as to why a lot of racing teams (professional, amateur, and FSAE) are switching to torsion bar style suspensions. I noticed at FSAE-M this year that Graz is running torsion bar suspensions and schools like Western Australia have been doing it for a few years now. Of course many LeMans and F1 teams have been doing it for a while now as well.
In the short track oval racing world I have always heard of people running transverse torsion bars on sprint cars, midgets, supermodifieds and the like because it lengthens the "spring base" and is supposed to slow the reaction of the suspension. Through all the research I have done in Miliken, Tune to Win, and a few other sources that the term "spring base" has never come up. I get the feeling it is somewhat like the oval term "bite" which means nothing to most in the vehicle dynamics world.
I'm going to guess that this slowed reaction of a torsion bar compared to a coil spring has something to do with the inertia of the torsion bar and arm package. With a greater inertia about the rotating axis of the torsion bar it might react slower than a coil spring of the same rate? Will this allow you to get slower, more predictable motions without having to use stupidly stiff rebound settings on the dampers?
With our FSAE car this past year we stuck with the coil springs without giving much thought to torsion mostly because a coil spring is so much easier to package. It's also much easier to change out when you want to make spring rate changes while testing.
Any other thoughts on this matter?
-Pete