6spdmalibu said:eibach springs f/r, 660lbs/in front, rear ??
GW negative roll system with Del a lum bushings top and bottom.
B body spindle with 1LE rotors
1 1/16 front sway bar with poly mounts and links.
Edlebrock IAS shocks f/r.
GW lower rear contol arms del a lum axle side, spherical frame side,
stock upper arms with stock rubber to limit bind.
stock g body rear sway bar for now, have a camaro style bar setup waiting to install.
i run the car on the street with out the rear sway bar in,
it under steers without it but handles better over rough pavement (less skipping = G's)
but when i push the car, it tends to snap over steer over rougher pavement,
hence why the torque arm set up. as it will allow me to set up the rear control arms to provide roll under steer while providing good anti squat characteristics.
torque arm setup will allow for a better performing suspension then the factory setup.
that is why i am trying to figure out proper setup for the g body.
If they're progressive rate rear springs, that may be your entire problem. The rate increases drastically when the spring compresses to the point where it reaches the stiffer rate coils & it really upsets the chassis. In any event, not knowing your rear spring rate doesn't help for tuning.
If they are single rate springs, I'm thinking they're a little too stiff, along wth a slightly undersized front bar. If the car understeers without any rear bar but has snap over steer on rough pavement, adding a rear bar won't fix it, especially going to a bigger one than stock like the Camaro bar you're intending. It'll oversteer sooner. I'd try an 1 1/8" front bar & no rear bar, that's what GW recommends with your suspension. Then to get rid of the rough pavement rear axle chatter I'd try softer rear springs, better shocks or both. You didn't mention what shocks you had, so it may just be a matter of adjusting the ones you have.
Tommy