Grond Control on 1st gen...
 

I have the ground control setup (camber plates, springs, Tokico shocks, etc) on an '85 GS. I'm getting ready to switch it over to my '85 GSL. Before I do, I have a question about the shock length.

Do these shocks need to be shortened? I have driven the GS (only once around the block) so I don't know if everything is on or not. The perches are fully adjusted up. Anything less and the spring is loose. You can pick it up and move it around. That can't be a good thing. What do I need to do?

The car is driven on the street as a daily driver and at autoxes. If I ever get any moeny, I'm going to do some track day events too. These are performance changes not a low rider wanna-be.

I don't know if I understand exactly what you mean.

Are the springs loose when the car is on the ground with the perches at less than the highest travel? That would mean there is a problem somewhere.

The springs will be loose when the tires are off the ground/the front end is jacked up. That is normal. Do not be concerned if that is what you mean.

Do I make sense?

Well, it's hard to see with the car on the ground. And I would expect more travel (looseness) with the car off the ground but damn!!! I need to put the wheels back on and turn the steering to the full stop. Then I might be able to stick my head under there enough to see.

If the perchec are raised all the way up, then you must have the front higher than the rear, which is never good. The springs will be loose at full droop, as in with the tires off the ground, and suspension let all the way down. To test if the springs are seated in and working at normal ride height, push on the fender and see if it bounces, which it should. If you have something way out of line, and something is binding, the spring will not seat all the way down, but the GC spring perches will usually align back in. If it really bothers you to see them loose, which it shouldn't, you can get some tender springs that will compress under the weight of the car, but keep the spring taut at full droop.
To make a story short, we have a first gen, GC fronts same as yours, and with the susp setup and slicks, can pick an inside front tire up on a hard turn. The spring will come out, just as when you jack it up, and instantly seat as it comes down. Hope this makes sense, and not make things clear as mud.

Cheers,
Travis

Something is wrong here. I have GC coilovers on the front of the car and CC plates, tokico adj. etc. And I can raise or lower it all day long and the spring is always loaded. Take another look under the car.

The stock springs are just so much bigger. They are loaded with the car on jack stands. The new ones are fine not that I have it back onthe ground on all four.

What should I set the camber/caster to? It will be a daily driver although I'm not too worried about tire wear so long as it is safe on the interstate.

Bob, you must be drinking your own beer again. :rlaugh:

The GC springs on my car are like you describe, a heckuva lot shorter. That's the reason for the threaded sleeves, to make up for that. No reason to shorten the shocks etc., when you jack up the front of the car the springs are going to rattle loosely. And yes, you will hear this BIG TIME when driving, you'll think the front suspension is gonna fall out. Remember when you drove my car at White Knoll? That's how it will sound and ride.

Your instructions should have included camber and ride height recommendations, and they are definitely different for different brands of tires. Most of them are in the 3-3.50 degree range, with similar caster recommendations. Call GC, ask for Doug, and get him to fax you the recommendation sheet. I found out the hard way that you can't get more than about 2.75 degrees negative camber in the front unless you modify the upper strut mounting hole, which is a no no in CSP. You may be able to get a tad more by running less caster, Doug says if you have to make a compromise take the extra camber.

The toe out is what will kill your tires, GC recommends 1/8" toe out as a starting point. That, more than camber or caster, is what will grind away the tires. And it's why Stinky rides a trailer.

The ride height recommendations are on the same sheet, make sure that you weight the left side of the car when making measurements. I used bags of sand to simulate fat daddy. And don't ask how many bags, smart ass. :biggrin:

You gonna be at the BMW plant?

A couple of other thoughts:

If your front Tokico's are the racing Illumina's for the RX7 (I think the part number is 1048?) they are already designed for lowered cars. I would assume that GC sold you the correct ones if you bought everything from them. If they are standard Illumina's or the blue Tokico's, then you need to be sensitive with the ride height so the shocks don't bottom out.

Also, on the alignment, may sure your suspension bushings, ball joints, and steering linkage are all good and tight. If not, replace them. Then, for the street the alignment can be set to 1/8" toe in and still be livable on the interstate. My experience is the zero toe or tow out on the street makes the car a handful to drive at highway speeds.

Good luck!

The PERCHES on the coil over shocks are used for RIDE HEIGHT and PRELOAD OF THE WHEELS.....

That is why Eibach makes tender springs.. they are helpers that are REAL soft.. and when you Fly over a jump.. and the suspention droops.. without tender springs.. they flop loose at max suspention travel. WITH Tender springs.. they stay in place.

Soo Put eh car on jacks.. adjust the perches to the ride height you think you need.. lower the car.. make sure all tire pressures are the proper amount etc.. and bounce the car a few times.. roll it forward and back (to help with settling the suspension so the tires are not keeping it higher than it will be) Then measure from the ground to the bottom of the fender lip.
IF your car is not bent (IE fenders will never measure correctly) you should adjust eh coil over perches so that BOTH sides are the same height.
Do the same for the rear..

THEN Find a SCCA racer with scales... bring the car to them.. and then put it on the 4 point scales. You will see weights will be off. Fine tune the height at that point with each perch making smaller adjustments till you have even amounts between the left and right sides.

SOME people in the prod racing classes actually put a chain or cable from the "Frame" to the a-arm or axle to prevent droop beyond the spring's max travel length. This keeps the suspension closer to the car and helps keep the car controlled when you go over a rise etc.

Think of monster trucks.. watch Spike etc.. and see the monster trucks. or rock crawlers.. they almost all ahve limiters hooked to the axles to keep things in tight to prevent a lot of travel causing the car to become unbalanced.

So Yeah.. on jack stands it is normal... just adjust the position for the ride height you want and go from there.

(PS ISCRACING.net makes a adjustable coil height setup for the REAR of a 1st gen.. to correct ride height issues)

Is there a specific size of helper springs for the 2nd Gen RX-7 with Ground Controls? How do you determine what size you'll need?