d k

iTrader: (4)

Thats good enough.

Adding the bit about rear bar makes it more understandable for me

thank you

Sentic

iTrader: (1)

Thanks for all the info, I'll end up a lot stiffer than I thought, but with good sources.

ThePass

iTrader: (3)

The 1.6:1 thing is just an extrapolation of the widely recommended spring rate combos within the range of the majority of spring rates for this car (300-800 front). Whether you've thought about it in that context or not, that's the ballpark ratio that is usually being recommended with the most common sway bar combos. Nobody should get too hung up on it, it's not intended to be strictly accurate or reliable for every situation (i.e. a rule of thumb). There are many scenarios in which I'd recommend deviating from that. And as noted previously, that goes out the window after a threshold of about 800# based on several factors (and sometimes it goes out the window far below that threshold).

bbundy

Ive learned to not take those front roll couple numbers too seriosly. through testing different rates I ended up at 1000/500# thought I would need less front bar but ended up with the same bar settings I used with less front rate.

Sentic

iTrader: (1)

How much added body stiffness do you recommend with the stiffer rates. It seems like a full cage is good to have, but in my case I don't plan to use one. Seam welding and door bars is good and doable. I'm currently running frame rails and roll bar.

Anyone running 1000/500 or more without detrimental chassis twisting?

Savington

iTrader: (31)

The premise of the question is flawed. If you need increased front roll stiffness to prevent excessive pitching, as you seem to need, then the stiffness of the chassis doesn't have anything to do with it. Obviously a stiffer chassis is better, so if you can add frame rails or door bars without incurring the wrath of your particular ruleset, then those are good things to add, but they don't change the answer of "what spring rates do I need".

Sentic

iTrader: (1)

Thanks, my bad, the question would probably be: are all my grip and aero mods unnecessary since my chassis will twist like a wet macaroni and negate the gains since I don't have a full cage?
And I interpret your answer as "no, a full cage is better, but you will go faster with all that stuff and stiff rates regardless".

Savington

iTrader: (31)

You got it

Mobius

iTrader: (2)

Good info in this thread. Mt.net has matured somewhat, it seems; I'm surprised no one has done anything with this gem:

bbundy

I run my car in two configurations. Track and Autocross. in track form it has bolt in Roll bar, door bars, bolt in triangulated front strut bar that goes to the real firewall, bolt on rear sub frame brace that is triangulated forward into the floor pan. in Atocross form all the bracing is removed along with the rear sway bar. other than removal of the rear sway bar the only suspension setup difference is I run more toe out in the front for autocross. the car works well for both disciplines. lots more aero for autocross though. full 6" front splitter and full width double element APR GT250 wing. So yes for Autocross I run 1000/500 on a 1990 chassis with no stiffening add ons and it works. On the track Id say you would want at least door bars added to your roll bar as they are certainly an improvement.

I took the frame rails off some time ago. If you have good door bars you can't even notice the frame rails doing anything. Door bars are many times more effective. Door bars and frame rails are both not Autocross SSM legal mods though.

Bob