Join Date: Nov 2001
Location: state of confusion
Stabilizer bars directly reduce the independence of the right and left wheels. As long as the pavement is smooth, this isn't a big concern, but smooth pavement is frequently not the case.
Another issue concerns damping. You have one shock per corner that has to damp both pure vertical chassis "heave" motion and chassis roll motion. With a big bar and soft springs you might well end up being overdamped in heave (with likely ride quality consequences) AND underdamped in roll (think about overshooting in roll and a longer time for a "set" to take).
NASCAR "big bar/soft spring" thinking aside, big bars and soft springs do tend to provide a softer ride in OE production cars, since OE cars tend to be underdamped below the point of best grip anyway.
I *think* you want to first choose your springs based on ride frequencies and "flat ride" behavior over the range of speeds that you anticipate mostly driving in. There are some rough guidelines for the frequencies, to which I'd add that with smoother pavement you can go higher with spring rates and ride frequencies (softer and lower frequencies for rougher pavement). Then choose the bars based on some target amount of roll per lateral g and overall front:rear balance of lateral load transfer. Tune your damping - I'm assuming at least single adjustables here - based on observing transient behavior. There's a Koni shock tuning procedure floating around that basically has you starting out full soft and adjusting upward.
There is another input to your choice of springs, and that is the amounts of anti-squat and anti-dive geometry that are present. With greater amounts of these "anti's", you'll need less spring to keep from having excessive vertical motion under acceleration/braking (or possible bottoming in the extreme). But don't go overboard with increasing the anti's solely to allow running softer springs, as this has some downsides if taken to extremes (think rear axle "brake hop" for one, unusually harsh front ride quality when braking on rough surfaces or over bumps for another).
There are many compromises.
Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
Wife's: '10 Legacy 2.5GT (DD, six-speed manual)
Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
Various Loose Parts: '79 Malibu
Last edited by Norm Peterson; 01-05-2011 at 08:11 AM.