Torsion bars
I think the 1.03" bars would be
perfect for street use.
Too stiff? I have 1.12" torsion bars on my Duster. That's a 300 lb/in wheel rate. Using Fox shocks with them I wouldn't even say that the ride on my Duster is "too stiff" for the street. It's very similar to a modern performance car. Obviously not everything is comparable, but the ride quality of the 1.12" bars in my Duster is very similar to my g/f's 2013 Mustang with the suspension upgrade. And I run 18" rims and 35 series tires.
I'm with abodyjoe, although I personally wouldn't go below a 1" bar. I had 1" Just Suspension bars on my Duster before I upgraded to the 1.12's. They were a big improvement over stock, but they were still too soft for the performance I wanted. So they came out. And my Duster is not a heavy car, its a 340 4 speed with no A/C, manual steering, manual brakes, and lots of aluminum parts (iron heads though).
The Mopar performance chart, while handy for the spring rates it provides, is outdated on its description of the bars' performance. Tire and shock technology has improved significantly since that chart came out, and that means higher spring rates.
Something else about torsion bars that crossed my mind recently... I don't know how much longer a B-body torsion bar is or if their hex ends are the same size as a-body but.. When fitting the A500 or A518 trans in a A-body, What if the entire torsion bar cross member could be moved rearward to achieve clearance ?
That's actually a REALLY good idea. B/E body torsion bars are 41" long, A body bars are 35.8". The hex ends are the same size, so if you moved the A body crossmember back 5.2" you could use the B/E body torsion bars. The spring rate would be slightly different than advertised because it takes into account the length of the LCA, which is shorter on an A-body, but you could calculate that knowing the length of both LCA's to get the spring constant for the bars. If 5.2" would get you enough clearance, it might work really well.
