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Old 06-12-2010, 05:50 AM   #1
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Default Ride Height for my suspension setup?

I bought a 'package deal' suspension setup from a Miata autox'r which consists of the following (installed on my 90 Miata);

- NA koni sports (I'm pretty sure they are the NA version, is the NB version different?)
- ebay coilovers
- 550F / 340R (6" each I believe)
- 36mm FCM stops - 1/4" white plastic spacers added, plus the typical koni 'split' spacer (thin)
- FCM NB upper mounts
- RB hollow front bar (1 1/8")

I installed them as I received them as far as ride height. This resulted in ~12 - 12.5" RH (measured the usual way).

Closer examination of the front has shown the following observations:

- at full droop the total available travel before contacting the bumpstop is about 3/4" (didn't measure accurately, but that is in the ball park).
- at ride height (again ~12 to 12.5") it rides FULLY on the bumpstop.

Now of course I'm thinking, ok.. I should raise it up. But I have a few questions:

(1) I'm surprised that there is only 3/4" of travel at full droop (this obviously has nothing to do with my ride height setting). Is this normal?
(2)Why is it on the stops.. don't most folks run ~ this low?
(3) When I raise it up, do I need to be in the 13" range.. almost seems like there is a minimum RH I need to run with koni sports / 36mm stops (I realize this number is effected by my spring rate as well).
(4) Should I remove the thick white spacer (I thought I read it was there because Koni sports needed it?)

Thanks for any guidance. I did attempt some searching but I'm not really sure WHAT search terms to use to track down this sort of thing.

Much appreciated.

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Old 06-12-2010, 07:42 AM   #2
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Correction.. my travel at full droop is incorrect. That 'measurement' (more of an approximation) was done with only one side of the car jacked up and the big sway bar still attached. So that would affect that number.

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Old 06-12-2010, 10:40 PM   #3
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My suspension is extremely similar to yours but with 450/300 springs that are 7" free length, and actual Koni sleeves not the ebay ones, and an FM solid front bar versus the RB hollow. But I generally know where you're coming from.

6" is getting on the short side for a 340# rear spring IMO. In fact with 300# springs I could easily run 8" springs. If it feels like you're on the bumpstops, have you verified that it's not coil bind?

I'm at around 12.5" front, maybe just a tad lower, but if you go lower than about 12.25" on the fronts you are going to encounter occasional issues with clearing speed bumps if it's a street car. My ride heights are not all exactly even or symmetrical, because in the end the spring perch height was determined by corner weighting the car.

DO NOT remove those spacers on the shocks. Maybe you could live without the 3mm one, but not without the 9. I run them both. The reason is that Koni sports bottom out with about 12mm of shaft sticking out of the body. If you remove those spacers there is some risk that the shaft could bottom out inside the shock, which is not good.

Bottom line is you can't run absurdly low ride heights with these spring rates. 13" is unnecessarily high but 12.5" front and 1/4-1/2 higher in rear should be in the ballpark. If it's not a street car you can go a little lower and you might just rub the fender liners a bit depending on your wheel & tire combo.
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Old 06-13-2010, 09:03 AM   #4
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i have CG sleeves and 550/350 on my 99. I want to say I am at about 12.5". It is a sports package and I set them to about stock height for a sports (lower than a regular miata)
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Old 06-13-2010, 11:04 AM   #5
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yeah with those shocks you can't really go that low without messing up shock travel. The way a lot of guys get a lower height is with adjustable perch/short body shocks and the GC's. There is fairly limited shock travel as is on these cars so its tough to keep good travel and lower the car much with this setup
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Old 06-13-2010, 11:36 AM   #6
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I'm running 8" 250# springs and could go with 9". I need to run lower than 13" ride height in the rear to keep from coil bind.
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