long post, broken into three sections. car is a 70 duster, 17x8 wheels with 255 rubber at all 4 corners, aluminum headed 360, 5 speed, efi, currently with .89 torsion bars, 340 leafs, subframe connectors, biggest addco swaybars, KyB shocks, firm feel stage 3 box, etc. problems are body roll at autocross, undersprung (bottoming), and odd ride from the KYB shocks. primary use is street car (occasional multistate trips with the family) and monthly autocross.

1. what sixze and brand torsion bars do I want? im thinking 1.03, but have heard all sorts of things positive and negative about PST and other brands. im on a slim budget, so cost is an object. what size, and why?

2. the leaf springs I want for my duster are either not available, or way to expensive. so ive been looking into modifying my spring pack.

is there a way to figure out rates? like measuring individual leaves and doing some math?

what does clamping do to the rate?

some leafs have an additional half leaf on TOP of the main leaf. they state that this is to reduce brake hop. does this leaf add into the additional rate? does it actually work?

rubber or poly spring eye bushings and why?

sliders on a street car: yes/no and why?

3. i have a line on a full brand new set of spax adjustable shocks for 250 shipped.

im thinking that an adjustable will aloow me to go with softer valving for ride quality, and stiffer for autocross. other than the konis on my ACR (which I never got the opportunity to adjust) ive never had higher end or adjustable shocks. the KYBs suck. I know bilsteins and like them, but never ridden in or driven a set on a vintage mopar.

what says the hive? Spax what I want, as far as a cheaper koni type shock?



thanks guys. feel free to get into hardcore tech here. I know im not looking at bolt ons or the more normal type of things. im also considering additional unibody stiffening at this time, such as torque boxes and a lower radiator brace, but with it being a fully painted and detailed car, im not sure I can bring myself to do it. paint and body is expensive.