Setting up Coil-overs on the '93 Miata

Brad Mackey · **Posted:** Mon Apr 03, 2006 4:58 pm

Intalled new Ground Control Coil-overs on Bilsteins this weekend.
Set each perch at 1.000" from the bottom of the threaded sleeve.
Trimmed the Bump Stops per GC's instructions, taking off the first section, which was about 3/4".
Springs are: Front-700-lb. X 6"; Rear-325-lb. X 7"
Initial Results:
Front ride height (c/l of wheel to fender lip): 12-3/4"
Rear ride height: 13-1/8"
Shock Free travel: about 1-1/8" +/- 1/16"

Car sits a little higher than with the previous Eibach "Street" springs.
Couldn't corner weight the car.

Questions:
1.) Enough shock travel?
2.) Does the ride height look right? Could I lower the car more?

Gonna run it as is at VIR this weekend, but could do some adjusting in the pits.

Karl Shultz · **Posted:** Mon Apr 03, 2006 5:28 pm

Wow, a Miata thread and I can actually help. That doesn't happen often.

Bowie Jr's ITA Miata happens to be in my garage. Its ride heights are:

12.5" front
12" rear

That's empty with about half a tank of gas in it. Measured he same way you did, from the center of the hub to the top of the fender. The car is sitting on 15x7 Racing Dynamics wheels with 205-50-15 Hoosiers on them.

Important - Bowie's got some sort of short-bodied, race valved Konis on the car. So I suspect we have a lot more wheel travel than you probably do. I know he's also gone in and done delrin bushings - no idea if any of them are offset or not.

And do set the cross weights. Makes a bigger difference than a lot of people think.

To test wheel travel, here's a tip. Take a zip tie and, with the car sitting at its static ride height, wrap the zip tie around the damper shaft at the bump stop. Go out and do a session, trying to stay on track and not clobber the curbs. Come back in. If the zip tie is wedged way up into the bump stop, you're running out of wheel travel and need to raise the height of the car (or look for shorter shocks, or both)

Diane Hall · **Posted:** Mon Apr 03, 2006 5:51 pm

My car's rear is higher than the front to get the weights right on the corners. (They called that "rake".) Didn't do that on my own either... the Flatout guys helped, and they know what they're doing. I'd measure it for you if I could, but it's living at a friend's place for now.

I've got the SM suspension on the car.

Diane

Brad Mackey · **Posted:** Mon Apr 03, 2006 5:59 pm

Good advice, Karl, on the tell-tale tie-wrap. I'll do that on the first session.

Dianne: Mine's the SM as well, except for the shocks, I guess.

We'll see how it goes...

Ryan Holton · **Posted:** Mon Apr 03, 2006 6:03 pm

My Miata is setup at the same heights at the Gray/Shultz mobile. I also have short-bodied shocks as well.

I need to corner weigh mine as well :oops:

I borrowed the damn scales from Feinberg and couldnt find a good flat spot :roll:

Marty Howard · **Posted:** Mon Apr 03, 2006 6:35 pm

Out of curiosity I just checked Mine.

it's 11 3/4" F
12 1/2 R.

Karl Shultz · **Posted:** Mon Apr 03, 2006 7:03 pm

Ryan Holton wrote:

My Miata is setup at the same heights at the Gray/Shultz mobile.

No idea on the rake thing and why his (and I guess Ryan's) has the rear ride height set lower than the front. I can tell you that the car works very, very well.

What spring rates and lengths is the SM suspension? Being that it's not my car, I've got no idea what we're running, but I know it's "not the SM suspension."

Ryan Holton · **Posted:** Mon Apr 03, 2006 7:08 pm

Karl Shultz wrote:

Ryan Holton wrote:

My Miata is setup at the same heights at the Gray/Shultz mobile.

No idea on the rake thing and why his (and I guess Ryan's) has the rear ride height set lower than the front. I can tell you that the car works very, very well.

What spring rates and lengths is the SM suspension? Being that it's not my car, I've got no idea what we're running, but I know it's "not the SM suspension."

Mine fo' damn sure isnt the Spec Miata suspension. I actually like driving mine on the street!

I have 7" springs on Bilsten PSS9 coilovers, 458F/287R. I may bump the rear up a bit later in the year. It was completely neutral at VIR North.

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

I'm running 12.38 F and 12.75 R. Now that I shaved off even more of the poly bushings, I've eliminated rear bind and it's even more fun and not as bouncy.

Bowie Gray Jr · **Joined:** Mon Sep 13, 2004 8:31 am **Posts:** 98

Karl Shultz wrote:

Wow, a Miata thread and I can actually help. That doesn't happen often.

Bowie Jr's ITA Miata happens to be in my garage. Its ride heights are:

12.5" front
12" rear

To test wheel travel, here's a tip. Take a zip tie and, with the car sitting at its static ride height, wrap the zip tie around the damper shaft at the bump stop. Go out and do a session, trying to stay on track and not clobber the curbs. Come back in. If the zip tie is wedged way up into the bump stop, you're running out of wheel travel and need to raise the height of the car (or look for shorter shocks, or both)

Important note: You can't run this low effectively without fairly stiff rates and/or shortened shocks.

My car has 650lb front, 325lb rear (I think, Shultz can tell you if he looks at the rear springs) ST front sway, no rear sway.

Les Davis · **Joined:** Fri Aug 29, 2003 2:04 pm **Posts:** 2059

Ryan Holton wrote:

My Miata is setup at the same heights at the Gray/Shultz mobile. I also have short-bodied shocks as well.

I need to corner weigh mine as well :oops:

I borrowed the damn scales from Feinberg and couldnt find a good flat spot :roll:

Are you sure about that, lower in the back than front? If so that might explain some of the handling difference I've noticed in the car. Hmmm...

Double check that and get back to me Ryan. I'm really not eager to go changing my ride height since that then requires a re-corner weighting and re-alignment.

BTW, My car is 12.5/13.0 F/R ride heights.

Karl Shultz · **Posted:** Tue Apr 04, 2006 12:58 pm

Les Davis wrote:

Are you sure about that, lower in the back than front? If so that might explain some of the handling difference I've noticed in the car. Hmmm...

I won't speak for Ryan, but I'm sure about it for Bowie's car. Just double checked it here at lunch.

Rich Anderson · **Posted:** Tue Apr 04, 2006 1:01 pm

Karl Shultz wrote:

Les Davis wrote:

Are you sure about that, lower in the back than front? If so that might explain some of the handling difference I've noticed in the car. Hmmm...

I won't speak for Ryan, but I'm sure about it for Bowie's car. Just double checked it here at lunch.

Where do you measure the ride height? Based on Les's figures of 12.5 and 13, unless he is using the metric system, I assume that it is not the bottom of the rocker panel.

Brad Mackey · **Posted:** Tue Apr 04, 2006 1:07 pm

Rich:
AFAIK, its the measurement from the C/L of the wheel hub perpendicular to the lip of the fender. Depending on how straight you can keep your tape, you should be able to get it within about 1/8".

Bowie Gray Jr · **Joined:** Mon Sep 13, 2004 8:31 am **Posts:** 98

Rich Anderson wrote:

Where do you measure the ride height? Based on Les's figures of 12.5 and 13, unless he is using the metric system, I assume that it is not the bottom of the rocker panel.

Quote:

Measured he same way you did, from the center of the hub to the top of the fender.

If you measured from the ground to the rockers (or what is left of my rockers, they have led a hard life) the right height is very close to 5" front, a tiny bit more rear. Or at least that is where I used to run them. I have no idea how far from that they are now that I knocked the nose of the car and OPM rebalanced it afterward. I know the car works REALLY well, which is what matters.

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