Advise Needed for Ideal Ride Height

[DerekW]

Updated: setup

Hi guys,

I'm setting up my 06 Z for auto cross and track days. But before I install my parts, can anyone advise me on what the minimum ride height should be to allow sufficient piston travel?

I searched on the forum, but most discussions on ride height are only for "show" and not for "go". If I overlooked any threads, please point me to the right direction.

My setup includes the following:
Bilstein PSS revalved
Hypercoil springs 500lb/in, front and rear
Quaife LSD
Street tires
front/rear camber arms and rear mid-link to allow proper alignment

The planned alignment is -1.5 f/r camber, 0 f/r toe. My driving style is conservative, slow in, fast out and NO drifting. I welcome any advise on the alignment also

Ideally, I would setup my car with telemetry and free track time with engineering support. But the recession is rough on racing budgets LOL

Thanks again guys!
Derek

[PDX_Racer]

Which do you want to do more? Check the rules for what you want to do more, and then set up the car for that, and compromise on the other (not that it is that much of a compromise).

[guitarist]

Originally Posted by DerekW

Hi guys,

I'm setting up my 06 Z for auto cross and track days. But before I install my parts, can anyone advise me on what the minimum ride height should be to allow sufficient piston travel?

I searched on the forum, but most discussions on ride height are only for "show" and not for "go". If I overlooked any threads, please point me to the right direction.

My setup includes the following:
Bilstein PSS revalved
Hypercoil springs 500lb/in, front and rear
front/rear camber arms and rear mid-link to allow proper alignment

The planned alignment is -1.5 f/r camber, 0 f/r toe. My driving style is conservative, slow in, fast out and NO drifting. I welcome any advise on the alignment also

Ideally, I would setup my car with telemetry and free track time with engineering support. But the recession is rough on racing budgets LOL

Thanks again guys!
Derek

My experience lies mostly in autocross and not road courses, but I've done a good bit of work getting my car setup to a point where it's very fun and easy to drive.

If you're going to be using street tires (even the super sticky breeds) I'd recommend going with a touch of toe-in at the rear. It makes the car much more controllable on corner exit. The Z tends to add a little dynamic toe-out under acceleration, and it's noticeable if you have the rear set at 0 toe.

Also, I've found -3 degrees front is great, very even tire heating and wear. In the rear, -1.7 or -1.8 is probably about ideal. I've gone as far as -2.5, but that just induces more wheelspin, especially inside wheelspin at exit with the stock viscous diff, than it enhances lateral grip.

As for ride height, I stuck with stock for street clearance and as long as you're well-sprung, you won't get much body roll. The Z isn't exactly monster trucking as it is. If stock feels too tall for you, lower it down in increments from there, but if you go much beyond 1-1.5", you're probably going to need to get the shocks shortened to keep from bottoming out at max travel.

Also, 500/500 f/r spring rates are probably going to bias the car's handling toward fairly tail-happy. I'm running 650/500 f/r right now and it's really well-balanced for autocross--the rear rotates under trail braking and throttle-on, but is otherwise very tame. Breakaway is progressive and controllable.

Don't know if your Bilsteins are valved for that much spring, but if they are, I'd up the front rates a bit. You might also look at dropping the rear rates a tad. I think the Grand Am guys were running 500/425 f/r on 2900lb or so cars, just as a point of comparison.

All of the stuff I've mentioned that can contribute to a loose setup will probably be twice as important for the speeds you'll see on an average road course, especially under braking and quick elevation changes.

Anyway, that's all I've got for you. Hope it helps, even a little.

[terrasmak]

Originally Posted by guitarist

Also, I've found -3 degrees front is great, very even tire heating and wear. In the rear, -1.7 or -1.8 is probably about ideal. I've gone as far as -2.5, but that just induces more wheelspin, especially inside wheelspin at exit with the stock viscous diff, than it enhances lateral grip.

I run -1.8 front and have a 7 degree difference in temp from outside to inside. This is for the roadcourse on street tires. Autocross and R comps, will be different. The rear i run -2 and am backing off the camber to -1.8 to try get a little extra drive out of the corner.

[DerekW]

Thanks for all the great responses guys! Please keep it coming to help out the rookies This board is a great source of information.

Originally Posted by PDX_Racer

Which do you want to do more? Check the rules for what you want to do more, and then set up the car for that, and compromise on the other (not that it is that much of a compromise).

I'm setting up for 70% road course 30% auto cross. There is so much for me to learn!

Originally Posted by guitarist

My experience lies mostly in autocross and not road courses, but I've done a good bit of work getting my car setup to a point where it's very fun and easy to drive.

If you're going to be using street tires (even the super sticky breeds) I'd recommend going with a touch of toe-in at the rear. It makes the car much more controllable on corner exit. The Z tends to add a little dynamic toe-out under acceleration, and it's noticeable if you have the rear set at 0 toe.

Also, I've found -3 degrees front is great, very even tire heating and wear. In the rear, -1.7 or -1.8 is probably about ideal. I've gone as far as -2.5, but that just induces more wheelspin, especially inside wheelspin at exit with the stock viscous diff, than it enhances lateral grip.

As for ride height, I stuck with stock for street clearance and as long as you're well-sprung, you won't get much body roll. The Z isn't exactly monster trucking as it is. If stock feels too tall for you, lower it down in increments from there, but if you go much beyond 1-1.5", you're probably going to need to get the shocks shortened to keep from bottoming out at max travel.

Also, 500/500 f/r spring rates are probably going to bias the car's handling toward fairly tail-happy. I'm running 650/500 f/r right now and it's really well-balanced for autocross--the rear rotates under trail braking and throttle-on, but is otherwise very tame. Breakaway is progressive and controllable.

Don't know if your Bilsteins are valved for that much spring, but if they are, I'd up the front rates a bit. You might also look at dropping the rear rates a tad. I think the Grand Am guys were running 500/425 f/r on 2900lb or so cars, just as a point of comparison.

All of the stuff I've mentioned that can contribute to a loose setup will probably be twice as important for the speeds you'll see on an average road course, especially under braking and quick elevation changes.

Anyway, that's all I've got for you. Hope it helps, even a little.

How much rear toe in would you recommend?

My shock builder said the valving allows for 500 +/- 100lbs. He's well respected in Miata circles and expanded to the Z with some happy customers. I will experiment with rate combos and report back

Originally Posted by terrasmak

I run -1.8 front and have a 7 degree difference in temp from outside to inside. This is for the roadcourse on street tires. Autocross and R comps, will be different. The rear i run -2 and am backing off the camber to -1.8 to try get a little extra drive out of the corner.

My starting point will be -1.8f/r camber and 0f ?r toe in with a 1" f/r drop.

To add more information, I'm running on street tires and have installed a Quaife LSD. A friend, who races spec Miatas, will help me with initial setup. Fine tuning will be done with all of my racer buddies. Most seat time will be in karts for now. The Z will be for fun, as I'm no where near competitive

Thanks again everyone! I hope to see you guys on the track in the near future

[scotts300]

Originally Posted by DerekW

Thanks for all the great responses guys! Please keep it coming to help out the rookies This board is a great source of information.


I'm setting up for 70% road course 30% auto cross. There is so much for me to learn!


How much rear toe in would you recommend?

My shock builder said the valving allows for 500 +/- 100lbs. He's well respected in Miata circles and expanded to the Z with some happy customers. I will experiment with rate combos and report back


My starting point will be -1.8f/r camber and 0f ?r toe in with a 1" f/r drop.

To add more information, I'm running on street tires and have installed a Quaife LSD. A friend, who races spec Miatas, will help me with initial setup. Fine tuning will be done with all of my racer buddies. Most seat time will be in karts for now. The Z will be for fun, as I'm no where near competitive

Thanks again everyone! I hope to see you guys on the track in the near future

We were just AT the track (Thunderhill) - too bad you weren't ready yet!

[DerekW]

Originally Posted by scotts300

We were just AT the track (Thunderhill) - too bad you weren't ready yet!

I can't wait to get to the track and meet others who share my interests Many of my friends do track days at TH in Miatas, maybe you had met them before. My Z should be ready by end of this week

[guitarist]

Derek: to answer your question on toe:

On street tires, I ran 1/16" total toe-in rear and 1/32" total toe-in front (or half those numbers per side).

On race rubber, 0 toe in the rear and 1/16-1/32" total toe out up front worked well to get the car to rotate. Hot race 275/295 autocross compound (V710) rubber + fairly grippy concrete makes for some ridiculous levels of overall grip.

[z-u-later]

My Z is dropped about 3" and it handles well for both autocross and road courses. My entire suspension has been modified -- springs, shocks, sway bars, chassis braces, end links, front camber arms, rear arm/toe kit, shaved rear spring mounts, etc.

Here is my alignment specs:

Front: -2.0 Camber, 1/8" Toe Out
Rear: -2.0 Camber, 1/8" Toe In

[sektor 11]

Originally Posted by z-u-later

My Z is dropped about 3"

holy crap.

[Asterix]

A good place to start on ride height is wherever it needs to be so the lower control arms are parallel to the ground. I know the front arms are not straight, so put the front bolt on the chassis at the same height at the center of the lower ball joint(s). Same in the rear - make the arm with the spring on it parallel to the ground.

I know someone on this forum has posted toe and camber curves as the suspension goes up and down. You should find those and study them as well, since they'll give good insight into how ride height affects toe and camber.

Asterix

[guitarist]

Originally Posted by Asterix

A good place to start on ride height is wherever it needs to be so the lower control arms are parallel to the ground. I know the front arms are not straight, so put the front bolt on the chassis at the same height at the center of the lower ball joint(s). Same in the rear - make the arm with the spring on it parallel to the ground.

I know someone on this forum has posted toe and camber curves as the suspension goes up and down. You should find those and study them as well, since they'll give good insight into how ride height affects toe and camber.

Asterix

This is why I stuck within 0.5" of stock ride height.

[DerekW]

anyone know the stock ride height for the Z? fender to wheel center?

Thanks