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Login to post Forums » Grassroots Motorsports » Miata Suspension--What Would You Do?

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April 22, 2009 8:14 p.m. billy3esq Dork

My street Miata ('96 w/ 81k miles) is in need of new shock absorbers. When I bought the car 6 years ago with 48k, it needed new shocks, and, not knowing any better, replaced them with generic OE-replacement type shocks. A few years of autocrossing has probably led them to an early demise, although over 33k isn't terrible for ordinary shocks.

I don't ever drive this car in anger any more, although I might at some point take up casual autocrossing again. (By casual autocrossing, I mean I don't care anything about classing, competitiveness, etc.) So, the question becomes what should I do.

Has anyone tried the new Koni STR.T or whatever they're called? Are they any good?

What about putting a set of Koni sports on it? Using their adjustable spring perch to take a bit of the truck-like wheel gap out has some appeal to me? Does doing so require M2/FM mounts and/or revised bump stops?

What about Bilstein Sport and/or HDs? Would they be too harsh for the stock springs?

Should I just say what the heck and get a full on Flyin' Miata Stage 2.5 kit?

Discuss.
April 22, 2009 9:57 p.m. Salanis UltraDork

For a street car, I'd go with just the FM stage 1, and Fat Cat bump stops (but not mounts). Might as well spend the few extra bucks for springs that will be a proper mate to the new shocks.
April 22, 2009 11:10 p.m. alleykat New Reader

For a street car Koni sports are good. You can drop the car a bit using the Koni sports too. They have three spring perches on each shock. That is what I have been running the last 4 years.

Fat Cat Motorsports will re-valve a set of Bilstien sports. Combine those with a set of FM springs and you would have a very competent set up that was still comfy on the street. Plus the re-valved Bilstiens can handle much higher spring rates in the event you want to upgrade.
April 22, 2009 11:14 p.m. ReverendDexter HalfDork

I know when I get around to picking up a Miata, I'm just gonna get the Spec Miata suspension "kit". That might be a little bit more stiff than you're looking for, though.
April 22, 2009 11:20 p.m. Salanis UltraDork

Unless you're actually planning to run it in Spec Miata, I would not run that suspension. The spring rates on the front are too high for the Bilsteins. I've heard plenty of stories about how someone used a similar suspension setup, but with much lighter front springs, and it handled way better than a SM.

I've heard people say they have good luck with spring rates that high, on shocks meant for them. But I personally think 700# is too high for a Miata in general.
April 22, 2009 11:28 p.m. bluej HalfDork

Salanis wrote:

Unless you're actually planning to run it in Spec Miata, I would not run that suspension. The spring rates on the front are too high for the Bilsteins. I've heard plenty of stories about how someone used a similar suspension setup, but with much lighter front springs, and it handled way better than a SM.

I've heard people say they have good luck with spring rates that high, on shocks meant for them. But I personally think 700# is too high for a Miata in general.

agreed. i'm on 550 front, 350 rear and i would absolutely not recommend going higher if it still sees street use. in fact, i'm going back to stock springs with the koni adjustables until in about a year i can afford to get them rebuilt with minor revalve and switch back to something like a 400 front/250 rear with stiffer sways.
April 22, 2009 11:52 p.m. ReverendDexter HalfDork

Salanis wrote:

Unless you're actually planning to run it in Spec Miata, I would not run that suspension. The spring rates on the front are too high for the Bilsteins. I've heard plenty of stories about how someone used a similar suspension setup, but with much lighter front springs, and it handled way better than a SM.

I've heard people say they have good luck with spring rates that high, on shocks meant for them. But I personally think 700# is too high for a Miata in general.

Good to know.

I was basing this more on the fact I could get it for cheap, and it's a known commodity.
April 23, 2009 12:05 a.m. Salanis UltraDork

You can get virtually the same thing for waaay cheaper. Just buy the Bilstein shocks, get a set of threaded sleeves, and match them to springs of whatever rates you want. Race springs are easy to find and cheap. You can even experiment with different rates.
April 23, 2009 12:08 a.m. Keith UberDork

Salanis wrote:

For a street car, I'd go with just the FM stage 1, and Fat Cat bump stops (but not mounts). Might as well spend the few extra bucks for springs that will be a proper mate to the new shocks.

FYI, the Stage 1 kit from FM comes with four bumpstops, similar to the ones Fat Cat sells. No need to spend extra dosh. This is a fairly recent addition.

Agreed on the Spec suspension. I've asked top-level Spec builders, and they emphatically agree that they would change that suspension if they could. Too stiff in the front and underdamped. You can run some pretty high spring rates if you have the damping to match, but you need some pretty good shocks to make 500+ lb front springs work for the street.

One note - when you get custom-valved shocks, they're going to be valved for whatever springs you're running. Change those by a significant amount, and the valving won't be right. I'd recommend settling on a spring rate before shelling out for a revalve.

I like the Konis well enough when matched with stock springs. It's not the highest performance setup out there, but it works okay. It's what I put on my father's Miata. The biggest problem is that the '96 will still have a sky-high ride height even at the lowest perch - I think the drop there is about 3/4" from your current height.

It shouldn't be a surprise as to what's on my own cars, though Let's just say that the current FM suspension packages reflect my own preferences pretty well for some reason. My wife's street Miata - which sees long road trips, track days and autocrosses - runs a full FM 2.5 setup with the new bumpstops and it's pretty effective all around in my opinion.
April 23, 2009 6:20 a.m. Kramer Reader

I have 8-way KYB's on mine, and it's okay for street and autocrossing. The perches aren't adjustable, though, and I wish I had that option.
April 23, 2009 9:34 a.m. Type Q HalfDork

bluej wrote:

Salanis wrote:

Unless you're actually planning to run it in Spec Miata, I would not run that suspension. The spring rates on the front are too high for the Bilsteins. I've heard plenty of stories about how someone used a similar suspension setup, but with much lighter front springs, and it handled way better than a SM.

I've heard people say they have good luck with spring rates that high, on shocks meant for them. But I personally think 700# is too high for a Miata in general.

agreed. i'm on 550 front, 350 rear and i would absolutely not recommend going higher if it still sees street use. in fact, i'm going back to stock springs with the koni adjustables until in about a year i can afford to get them rebuilt with minor revalve and switch back to something like a 400 front/250 rear with stiffer sways.

I am running 500 front and 350 rear on a set of used "R" package Bilsteins. This works surprisingly well. On the relatively smooth roads of Northern California the is livable for me. The handling and grip are pretty amazing. Sometime soon I should havecustom valved Blisteins in the car.

I would suggest staying away from the AGX's. When I bought my car it came with FM springs and a set of AGX's. The ride was pretty harsh. The same springs on a set of Tokico Illuminas is far more pleasant. In fact the ride quality with the autox suspension I'm running right now is pretty much the same.

If you are just replacing dampers, I'd recommend the Illumina's and set of shorter bump stops from Fat Cat motorsports.
April 23, 2009 10:27 a.m. Xceler8x Dork

I've got the FM stage 1 kit on my car. Freakin incredible. The ride, while set on 1, is damned close to stock. Turn the shocks up to 5 and it will be much stiffer. I haven't tracked the car with this setup yet but I'm sure it's going to work great from the around town testing I've done.

Sadly, I got in too late to get the bump stops.
April 23, 2009 10:51 a.m. Tom Heath Production Editor

There are few "known good" combinations out there; The FM kits have almost universal praise. Koni sports are also very popular.

We're getting ready to try something way outside the box for the Turbo Miata project by mixing NA and NB suspension components, a big front swaybar, and relatively soft spring rates. The idea is to develop something pretty comfortable with lots of capability. (Isn't that the Holy Grail...)

We'll let you know how that works out, but key players are Bilstein and FatCat Motorsports, and it looks pretty promising on paper. Stay tuned!
April 23, 2009 2:24 p.m. billy3esq Dork

I've been under the impression that if you lowered the rear any significant amount you had to go with either M2 or FM shock mounts to keep it from riding on the bump stops pretty much all the time. Now that the FM kits include revised bump stops, what is the advantage to the FM shock mounts? (Other than pretty anodized aluminum, of course.)
April 23, 2009 2:37 p.m. thatsnowinnebago HalfDork

ISC racing makes rear shock mounts too. I have them and it makes a big difference.
April 23, 2009 3:01 p.m. Keith UberDork

There's a big difference in intent between the FM mounts and the M2/NB/FCM/whatever mounts. The FM ones are designed to increase compression travel without affecting ride height. The NB ones - also sold by FCM - will lower the car. Based on the picture on the ISC site, those will as well.

If you're running adjustable spring perches, this is of no concern. But if you aren't, it's an important thing to understand. The FM mounts will offer a greater increase in travel than the NB ones in this case, and it appears the ISCs are similar.

Why are the FM mounts still useful now that we include new bumpstops? Because more travel is still useful . The more you can stay off the stops, the better. It's a less dramatic difference than it used to be, but it's still quite worthwhile.

Tom, we'll have one or two cars with the AFCO suspension at the Mitty. Are you going to have your Bilstein setup running by then?
April 23, 2009 3:04 p.m. mistanfo Dork

The pretty anodized aluminum was enough to get me to buy them. I did notice how much nicer the car drove over bumps after though.
April 23, 2009 4:12 p.m. Tom Heath Production Editor

Keith wrote:

Tom, we'll have one or two cars with the AFCO suspension at the Mitty. Are you going to have your Bilstein setup running by then?

Not likely. We're stuck waiting on a few more parts for the testing, including a set of 15x9.0-inch wheels and tires to fit on them.

I'd still like to try an AFCO car, because it looks like it could be a very practical dual-purpose setup.
April 23, 2009 4:21 p.m. Keith UberDork

Based on the speed on track, it's a pretty handy single-purpose setup too I have to admit I was quite surprised at their ability on-track given the original design intent. Turns out wheel travel is a good thing.

You'll definitely get a shot at an AFCO car. Just don't get distracted if the engine makes weird noises.
April 23, 2009 6:37 p.m. Wowak Dork

I also run the KYB AGX with stock springs and its tough to beat for the price. Granted if I could afford an FM kit I'd probably go that way in a heartbeat, but with the AGX set on 2 its a cushy boulevard cruiser, and with them dialed up its at least not embarrassing at an autocross.
Type Q wrote: I would suggest staying away from the AGX's. When I bought my car it came with FM springs and a set of AGX's. The ride was pretty harsh.
The AGX aren't up to the task of controlling anything beyond a stock spring.
April 23, 2009 7:41 p.m. Type Q HalfDork

Wowak wrote:
Type Q wrote: I would suggest staying away from the AGX's. When I bought my car it came with FM springs and a set of AGX's. The ride was pretty harsh.

The AGX aren't up to the task of controlling anything beyond a stock spring.

Thanks for the added information. My experience with them is limited to non-stock springs.
April 23, 2009 8:53 p.m. MrJoshua SuperDork

I have tein springs with AGX shocks on the daily otter. Its the smoothest riding vehicle in the family!

disclaimer-smoothestridingvehiclesinclude:onepoorly/cheaplycoiloversuspended wrx,onelandroverthatwhileridingsmootherthanthemiatatendstocrashover bumpssduetopoorinitialconstructionandoffroadsuspensiondesign.The miatawhilenotridingsofterridesbetter.Whiletherearemanyothercars" inthefamily"thatprobablyridesmoothertheyareeithernotinsured, notregistered,orjustnotreallyrunning,sotheyarenotincludedinthe designationof"inthefamily"forthepurposeofthispost.Alldriving isdonebyamatuersonopenroadsandshouldbeattemptedbyallthosereading.
April 23, 2009 8:59 p.m. ReverendDexter HalfDork

Type Q wrote:

On the relatively smooth roads of Northern California...

Yeah, all three of them.
April 23, 2009 10:32 p.m. Keith UberDork

Anyone in California complaining about the roads needs to go visit Michigan.

FYI, I think the KYB GR2 is basically the AGX set to "2". The AGX is an okay shock, but it gets harsh in a hurry when asked to deal with stiffer springs. I prefer the Tokico Illumina for aftermarket springs, and the Koni Sports work well with stockers.
April 23, 2009 10:44 p.m. Type Q HalfDork

Keith wrote:

Anyone in California complaining about the roads needs to go visit Michigan.

Exactly. Anyone who thinks Nor Cal "winter" is cold needs to spend December or January in Michigan as well.

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