^ this.

Torsion is carried by the OD of a tubular member, hence aftermarket bars that are stiffer are a larger OD. Tubular vs Solid really comes down to weight. In a torsion application, a hollow bar will do the same job OD for OD as a solid bar and be lighter.

Think of it this way, driveshafts are hollow. And they carry a lot of torque (torsion). A 6" OD d/s is going to be able to hold more torque than a 4" OD, same material. And since steel is stronger than aluminum, a smaller OD steel d/s is just as good in torsion as a larger OD aluminum d/s.

But not to confuse things, since there are no aluminum sway bars

 

yeah but your torsion bars are solid. if it didn't matter wouldn't they be hollow too. could you imagine the weight of a solid drive shaft. hahahha it wouldn't be able to be turned.

 

good read, http://temp.corvetteforum.net/c4/vad...bardesign.html

 

I'm saying solid vs tubular comes down to cost, in more ways than one. GM can probably make a cheaper bar out of solid steel, since, as stated before, they can buy the very expensive tooling once and make thousands of them. A smaller aftermarket place would be better off to invest in a better steel, buy tubes and bend them to spec.

Put it this way, if I could afford it, I'd run a large OD hollow sway bar.

edit: that's a REALLY good page on sway bars, nice find!

 

i like the hellwig's the best so far. they are made of 4140 chromoly and 1 3/8"(front) solid. and 1.25 adjustable for the rear. so you can shorten the lever arm and make the rear even stiffer.