Setting up Coil-overs on the '93 Miata

MartynWheeler · **Joined:** Mon Jan 02, 2006 9:30 pm **Posts:** 303

Hmmm. Going out on a bit of a limb here...

I would have thought the ideal situation would be even temperatures across the tread, meaning the full width of the tire was working fully.

In a real world of insufficient negative camber, however, the outside edge will always be working harder than the rest of the width, and the inside will be working less. That means that the closest to ideal you can get is an even temperature gradient across the width.

Aaron Buckley · **Posted:** Mon Apr 10, 2006 2:37 pm

Brad Mackey wrote:

I'm not surprised that Aaron got -3 Deg.

Looking at the dials on my rears on the my '93 Miata, they're at about 1-1/2 marks beyond the "neutral" center mark and that yeilds -2-3/4 degrees.

The fronts are at about the same location, and that yeilds 1.9/2 degrees.
I'm thinking I could get perhaps 3-1/2 on the front and maybe 4-deg. on the rears by rolling the cams over to max out.

Exactly. I ran -3 degrees because I wanted a crisp turn in without using toe out up front. If I were to track the car, I would considered dropping it down a .5 degree, but for autocross, it seemed to work, especially when you factor that the original Victoracers didn't like camber lacking cars. - AB

ColinOConnell · **Posted:** Wed Apr 12, 2006 12:12 am

Probably a stupid question: I just completed my install of GC's on new Koni's (and new bushings) and tried to set the initial position on the GC's by jacking up each wheel until the car was off the stand then measuring from the hub center to the fender. To get 13" all around, give or take. The adjusting ring is definately in different positions after doing this, left and right (by up to 1 1/2"). I'm assuming that after I run around a little it will settle and I can readjust.
How do you tune this?
Do I get the height settled in before I get an alignment?

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

You want the weight to be on the wheel before the measurement. Since the shocks aren't perpendicular to the ground, 1/4" on the GC isn't 1/4" total either. Expect to go through several iterations of this to get your ride height set. Drive around the block to insure that the suspension is settled before checking ride height after an adjustment. Even better would be to have a butt in the driver's seat since that'll affect the ride height a little, as it does with corner weighting.

ColinOConnell · **Posted:** Wed Apr 12, 2006 1:10 am

Wes Eargle wrote:

You want the weight to be on the wheel before the measurement. Since the shocks aren't perpendicular to the ground, 1/4" on the GC isn't 1/4" total either. Expect to go through several iterations of this to get your ride height set. Drive around the block to insure that the suspension is settled before checking ride height after an adjustment. Even better would be to have a butt in the driver's seat since that'll affect the ride height a little, as it does with corner weighting.

Should right and left be similar as far as the GC's are concerned? I've got the left front hub pulled for new wheel bolts to be pressed in tomorrow so I've got another day before rubber meets road. Once down, is it up and down on the jack until I find the 12.75" or so point?

ColinOConnell · **Posted:** Wed Apr 12, 2006 10:06 pm

Set the car down tonight and all I can say is WOOOWWWW! This is a new car, better than new actually.

Now to continue the questions. The spring perches are so different that I'm concerned. The rear clips are on the middle position, and the fronts are on the top. The hub center to fender measurements are all about 12.75" for now. Are these normal? If not wtf did I do wrong??

Kevin Hoff · **Posted:** Wed Apr 12, 2006 10:36 pm

You sure you put the right springs on the right corners? Like maybe you put a 6" spring on driver front and passenger rear instead of both 6" springs on the front?

On the question of "why measure hub to fender" - Subaru people always reference ride heights that way as well, probably for the same reason as it takes the tire/wheel diameter out of the equation. I saw something very interesting on the GRM website in the project car section a few weeks ago that is a great idea - Andy Hollis uses a set position on the suspension and shock mount to check his ride height. The benefit being consistency and lack of worries about uneven bodywork. The drawback of course is that it's impossible to correlate between different people/cars.

Brad, what are you doing to get enough rear wheel travel? When I had the Miata there was going to be no way to get enough rear wheel travel to go as low as you are posting without also using the fancy top mounts.

--Kevin H.

ColinOConnell · **Posted:** Wed Apr 12, 2006 10:49 pm

Kevin Hoff wrote:

You sure you put the right springs on the right corners? Like maybe you put a 6" spring on driver front and passenger rear instead of both 6" springs on the front?

Yeah, I second guessed that as well but they are correct. (I was pretty sure I didn't screw it up because we did one shock at a time, but being married I'm aware that I'm not perfect.) The numbers on the springs are the same right to left and they are correct front and back so I didn't cross them.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

ColnOConnell wrote:

Kevin Hoff wrote:

You sure you put the right springs on the right corners? Like maybe you put a 6" spring on driver front and passenger rear instead of both 6" springs on the front?

Yeah, I second guessed that as well but they are correct. (I was pretty sure I didn't screw it up because we did one shock at a time, but being married I'm aware that I'm not perfect.) The numbers on the springs are the same right to left and they are correct front and back so I didn't cross them.

My professional opinion is that your car must be shaped like a banana.

OK I exaggerate -- I'm not a professional.

The only cars that I have seen that needed that much "wedge" were cars that hit something previously in life. Hard. That is assuming it's all installed correctly. Corner weight scales, an alignment check, and a verrrry careful inspection of the unibody "frame" rails for creases might be a good idea at this point. It just ain't right.

Edit -

Please humor me (us?) and take a picture or write down here the exact spring numbers from each corner of the car -- including free length, rate, and coil diameter....

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

Colin, what were the initial settings for ride height and to what were your GCs adjusted? I assume that you had the same number of turns from bottom from left to right.

Todd Breakey · **Posted:** Thu Apr 13, 2006 5:38 am

It looks like something is wacky with your rear springs. I have the same shocks and springs on my Miata and all four corners are about the same (I haven't corner weighted it yet.) I'm sitting about 12.5 on the fron and 12.75 in the rear. The clip is set on the center and I have the spring perch at about 8 full turns from the top of the threaded collar.

Something looks wonky with your set up. You might need to call GC and find out. Someone on Miata.net had a similar issue and it turned out the sent him the wrong kit.

ColinOConnell · **Posted:** Thu Apr 13, 2006 8:13 am

To start with. the measurements were all about the same with the stock springs before I started. I forgot to write them down, but I did check. I've had it since new, and there have been no incidents that would warp the car.

Wes Eargle wrote:

Colin, what were the initial settings for ride height and to what were your GCs adjusted? I assume that you had the same number of turns from bottom from left to right.

Perch settings were at 1 1/2" from the bottom of the red tube all around as a starting point. I didn't record the ride height at that point because I was going for 13" as a baseline for the alignment. I jacked the back up and down while we dialed them in at 13" and then did the same to the front.

MikeWhitney wrote:

Please humor me (us?) and take a picture or write down here the exact spring numbers from each corner of the car -- including free length, rate, and coil diameter....

I'll have to do that after work. I'll let you know.

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

ColnOConnell wrote:

Perch settings were at 1 1/2" from the bottom of the red tube all around as a starting point. I didn't record the ride height at that point because I was going for 13" as a baseline for the alignment. I jacked the back up and down while we dialed them in at 13" and then did the same to the front.

And you settled the suspension by driving around before taking a measurement?

ColinOConnell · **Posted:** Thu Apr 13, 2006 10:37 am

Wes Eargle wrote:

And you settled the suspension by driving around before taking a measurement?

Sure did.... what fun!!!

I'm thinking I'll start the balance from scratch after work tonight. Set the perches about half way on the collars front and back and go slower and evenly into the 13".

If that doesn't work I'll stick matchbooks or sugar packs under one of the corners until it quits wabbling. :lol:

Brad Mackey · **Posted:** Thu Apr 13, 2006 6:16 pm

Hey.
Just LOOK at your photo's.
Somethin' be BAD wrong with your installation. NO WAY your perches should be incongruent to that degree.

Suggest you START OVER!!!

The difference in spring perch location shown in your photo's indicates a substantial difference in spring rates or free length from right to left side. Or, like Mike said, you got a weirdly warped chassis.

BTW, I got shock travel by trimming the bump stops by about 1", per Ground Control's instructions. I have about 1-1/8" of shock compression travel before bump stop contact, then perhaps an additional 3/4" or so of compliance in the bump stop before severe resistance. Ran VIR-N last weekend with no issues. Probably will drop another 1/4" all around for VIR-S in two weeks. My rates are F=700#, R=325#

Your results could vary...

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Setting up Coil-overs on the '93 Miata

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