I'm looking for some solid ride height recommendations. Right now I've got my coilovers set to just over a 2" drop all around. (23.9" from ground to base of fender lip on all four corners). For reference, this is about 6.5" from rear rocker panel to ground, and 5.5" from front rocker to ground.

I like the way it looks at this height, but am unsure if this is optimum for suspension performance.

This is a weekend street car, but I'm also looking to do occasional autox and curvy road driving. Nothing too serious, but I'd like to find a compromise.

What ride height settings is everyone running?

Does more or less rake actually cause significant performance enhancements/reductions?

Thanks.

 

 

Haha. I guess you're saying that a > 1" drop isn't hurting your car's handling?

I also assume you STX guys run smaller wheels for an even lower COG, with out screwing up the roll center?

I'm running 17's for now at least

 

What angle is your front lower control arm sitting at?
Have you determined your roll center height based on upper and lower control arms imaginary lines intersecting at the centerline of the vehicle?

What about your spring preload and corner balance numbers?
Just because you lowered the car, doesn't mean the weight from front to back and left to right are equal.

There is no "exact" answer, as there's PLENTY of variables, but if you want to go by the 'book of suspension design' for example FSAE or F1, you may want to read up on some technical vocabulary and take some home measurements.

- Erik

 

Thanks for the reality check

Honestly, at this point I'm not really concerned enough to make it perfect. I've got about zero preload on the springs, and don't plan to corner balance until later down the road when I've got a sway bar and some adjustable end links.

Right now I'm just looking for some reasonable guidelines to go with before I get it aligned. Just don't want to change my mind in a week, and have to get it aligned again.

I really need to break down and read a book on suspension dynamics, as I always get confused when it comes to roll center, stiffness, COG, etc.

 

Sure thing!

Since you're not check for weight distribution via a set a scales, place it where you personally want it.
Then I would say set it to a "level" that you feel comfortable driving deep into a corner with and try it out.
Take a look at some of the common lowering spring heights and adjust for your needs / situation accordingly.
You'll know what height you want within just a few days of driving.

- Erik

 

Sounds like I should just leave it as is, and feel it out.

 

Yessir, that's what I have learned. This car was set up by Turner Motorsports (who know a thing or two) so it reflects their experience as opposed to my amateur calculations. It will pull > 1.1g on street tires, and has been complimented by some National Champion drivers who have beaten me in it.

It suffers from the usual side effects of a competition setup, including a tendency to rub the chin spoiler on anything taller than 1.75".

In theory the roll centers are f*cked, but in practice it changes directions like a squirrel on steroids.

I'd go autocross what you have, and bear in mind that the driver is 90% of the outcome, and the tires another 20%... ;-)

If you get hooked and do want to tweak the chassis then I'd suggest getting your setup corner weighted. That's the surest path to a car that will behave the same way turning in either direction...

Enjoy, and may the force be with you!

Cheers,

Charlie