Tuned suspension project

[Edmundo]

I have a 2004 Pontiac GTO. I would like to improve upon the factory suspension and turn my car into a real sports sedan with easy, controllable and sure-footed cornering capabilities. I know many of you are more into chasis mods, however I would like to work with the original setup and use available, american aftermarket products. Intended use is street.

The info about the OEM package I have been able to gather is the following: 1. Wheels 8J x 17". 2. Tires: 245/45 ZR-17. 3. Spring rate: F: 175 lbs R: 320-400 progressive. 4. Sway bars: F: 1 1/8 R: 5/8. 5. Total weight 3,725 lbs. 6. Weight distribution: F: 55% R: 45%. 7. Shock absorbers: Monroe.

I would like to lower it as much as technically convenient. I have seen at least 2 coilover kits and 3 lowering spring sets. Edelbrock, qA1 and Hotchkis have nothing for this car yet. Will be looking into some alignment numbers after lowering.

Thank you very much for your help and advice.

[MrQuick]

welcome Ed, 2004 hummm, well you can increase spring #'s, lighten the car abit, fiber hood race seats or lighter brakes?, widen tire & rim size abit say 275-265 on 10x18's, lower 1 -1 1/2"s, stick with current sway bars, maybe set it up with coil overs or hell just better shocks and struts. Don't forget a caster camber kit... oh I forgot to start this by how far do you want to take it? try here GTO perf (http://www.lmperformance.com/h/43.html) or Rhys Millen motorsports (http://www.rmrproducts.com/index2.html)

[Edmundo]

welcome Ed, 2004 hummm, well you can increase spring #'s, lighten the car abit, fiber hood race seats or lighter brakes?, widen tire & rim size abit say 275-265 on 10x18's, lower 1 -1 1/2"s, stick with current sway bars, maybe set it up with coil overs or hell just better shocks and struts. Don't forget a caster camber kit... oh I forgot to start this by how far do you want to take it? try here GTO perf (http://www.lmperformance.com/h/43.html) or Rhys Millen motorsports (http://www.rmrproducts.com/index2.html)
Thank you. One of the things I worry about is Spring rate. The available coilovers (Whiteline and Norris Motorsports -reseller for JHP Au?) come with springs >300 lb front and >425 lb rear. Springs from Sprint and H & R are advertised as 25-30% over factory rate??? Only Eibach Pro-kit is close to factory rate, but only 1" lowering front and a miserly .8" rear. I remember once in a 92 Camaro, I ordered some Suspension Technique springs. They were extremely stiff! I combined a set of Koni Sport shocks and the shocks could not control the springs at any setting!

I will check the websites and follow with you.