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Old 12-19-2012, 09:07 PM   #1
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Default 1990 Suspension Spring Rates

My 1990 Turbo Miata came to me with the following suspension setup:

Ground Control/Bilstein coil overs with front 375# springs (part number GC150.64.66) and rear 250# springs (Part Number GC180.64.44).

Flyin Miata Frog Arms

Bad Dog Bolt in Rollbar

Cusco Strut bar.

The car is really harsh up front on fairly trivial bumps. I'm surious what others are running for spring rates because it just seems like the fronts are way to harsh compared to the rears.

Mike
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Old 12-19-2012, 09:10 PM   #2
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It has nothing to do with the springs (which are actually considered soft for a Miata) and everything to do with the shocks. If you want good ride quality, you have to spend $$$.

With today's shock tech, you can legitimately daily drive a car with 700/400lb springs.
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Old 12-19-2012, 09:10 PM   #3
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Quote:
Originally Posted by Mikelly View Post
My 1990 Turbo Miata came to me with the following suspension setup:

Ground Control/Bilstein coil overs with front 375# springs (part number GC150.64.66) and rear 250# springs (Part Number GC180.64.44).

Flyin Miata Frog Arms

Bad Dog Bolt in Rollbar

Cusco Strut bar.

The car is really harsh up front on fairly trivial bumps. I'm surious what others are running for spring rates because it just seems like the fronts are way to harsh compared to the rears.

Mike
It's not the springs rates. Could be bottoming, heavy wheels, too much air pressure, dead shocks. Those same spring rates with Ohlins, Afco's, FCM's Xidas ride quite well.


Edit: lulz at Andrew posting the exact same answer at the exact same minute..
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Old 12-19-2012, 09:57 PM   #4
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Quote:
Originally Posted by Savington View Post
It has nothing to do with the springs (which are actually considered soft for a Miata)
This.

375 / 250 is a pretty good springrate for a comfy daily-driver, but there are many more variables.

Shocks are one. Expensive shocks work better with stiff springs, there's no avoiding it. FatCat Bilsteins, Xida, Tein, even Koni Sports would be passable choices. Many of these will come with their own springs.

Ride height is a huge factor. Miatas don't have a lot of suspension travel, and if the car is substantially lowered, the distance between the top of the shock and the upper shock mount is reduced even further. If the car is lowered more than 2" or so, you're probably riding on the bumpstops, and the hardest spring is a hell of a lot softer than a compressed bumpmstop.

And that's another area that can be massively improved. The stock bumpstops on the NA are pretty hard, and too thick. You can install NB-style upper mounts and MCU bumpstops to gain both additional suspension travel and a more gradual transition when you do bottom out.


Three major companies to deal with here:

Automotive Suspension Experts | Fat Cat Motorsports | FCM Elite shock absorbers

949 Racing - 6UL 6ULR wheels - Miata performance

Flyin' Miata : Chassis : Suspension components

FatCat is geared towards the street and AutoX crowd. 949 is all about "real" track racing.
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Old 12-20-2012, 03:46 PM   #5
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Originally Posted by emilio700 View Post

Edit: lulz at Andrew posting the exact same answer at the exact same minute..
Great minds and all
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Old 12-20-2012, 03:49 PM   #6
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Mike if you think/thought your setup is/was harsh, you should have felt mine with konis with any rate spring.

I'll let you drive mine with tien flexes if you want.
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Old 12-20-2012, 09:31 PM   #7
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Dude you've seen and been in it. MIght well be the bumpstops/mounts. That's something I forgot that I replaced when I built the Specmiata. I'll try that first.

You going to be around next week? I might drive the GT3 in a few days next week, and I could swing by and let you drive it, and check your Miata out.

Mike

Quote:
Originally Posted by Braineack View Post
Mike if you think/thought your setup is/was harsh, you should have felt mine with konis with any rate spring.

I'll let you drive mine with tien flexes if you want.
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