Miata suspension advice request

I know I should know these things by now but I just like to get a few other opinions.

My '97 Miata is slowly transforming into a CSP car. Until this year I ran a FM 2.5 suspension system which was great on the street but a bit soft for track/autocross use. And investigating rub marks I found the 275 Hoosiers (pinched onto a 7.5" rim) were rubbing the coils. So that setup has been sold and I have a line on a Spec Miata setup. Never installed but a few years old, Bilsteins, 700/375 springs, bars and end links and all in my budget.

Any problems suspected with this setup? The car get very little daily driving use anymore but local autocrosses and more and more track days are in its future.

Send HunterJP a pm, or maybe he will chime in here. He's a CSP national champ and could probably point you in the right direction.

The Bilsteins are underdamped in that setup. SM setups are cheap but not the best.

You might want the rears slightly stiffer than 375, but 700/400 is a sound starting point. There are some people who are demented and run up to 800 in the front. If your lots are smooth, you're already on Hoosiers so it might work.

Keith already covered the shocks.

CSP is a black hole of money. You could do just about anything. I talk with Bob and Billy Davis on occasion since they run in the area and their car is the utmost limit of what you can do with CSP and it's insane.

They run custom Penskes, but I'm not sure what spring rates they run. They run custom made 11" rims on their car. I wouldn't run a 275 on anything less than a 10" rim and for that on an NA you need to do some fender surgery.

I wouldn't run a Spec Miata setup for CSP. It's basically a cheap setup to get people in line with a race series. Poor damping and the spring rate is not optimal for autocrossing. Way too much front spring at 700 front for an NA 1.8.

If you don't have money to spend then don't do CSP. If you're just looking to have fun and be in CSP then do whatever you want.

Harvey wrote: If you don't have money to spend then don't do CSP. If you're just looking to have fun and be in CSP then do whatever you want.

That statement makes me angry. Miata.net guys say the same lame thing.

I'd love to make a CSP car for the Challenge, and see how it does in the real world.

alfadriver wrote:

Harvey wrote: If you don't have money to spend then don't do CSP. If you're just looking to have fun and be in CSP then do whatever you want.

That statement makes me angry. Miata.net guys say the same lame thing. I'd love to make a CSP car for the Challenge, and see how it does in the real world.

What makes you angry about it?

The truth is that it's going to be super difficult to compete at a national level without spending some coin on your setup. If you just want to have fun at a local level then you can do whatever you want.

A challenge budget CSP car isn't going to be able to do anything at a national level IMO.

In reply to Harvey:

So CSP is all about throwing money at it, then. The driver with the most money wins. That's what pisses me off.

In reply to alfadriver:

There are other classes where putting money into modifications is not required, but CSP is not one of them. Did you figure you were going to show up in a stock Miata on Hoosiers and compete in a class that allows nearly anything to be done to the car? Not sure why this is something to be pissed about. Are you pissed that NASCAR requires millions of dollars to run in? By that metric CSP autocross is a bargain. Probably $10-15k investment will get you into something decent for CSP, but a spec Miata suspension and Hoosiers on 7" wheels isn't going to do it. If you only have $1k to throw at mods SP classes aren't the best choice.

I've seen a National level CSP Miata up close, and it's the obsessive attention to detail that stands out. A tiny alternator. Drilled out brake rotors. Extensive dyno testing to determine the ideal length for the pre-throttle body intake tube. Like everything, you can substitute effort for money - but it's a highly competitive class, so if you're not spending the time/money, you'll lose to someone who is.

FYI, general rule of thumb for NA/NB Miata spring selection: use a F/R ratio of about 3/2. You might want to tweak the final result one way or another, but that'll get you in the ballpark. Note that the SM setup is way off this ratio.

You're looking at buying a suspension no one would put on a serious STS car, and planning to play in the harder class. Why not build for STS...? Done well, it'll be faster than a half-assed CSP car on Hoosiers. Really.

Let me back up and say: I have no desire to podium at Nationals. I recognize that is out of my budget and talent. I want to do well locally, this last year to 7-8th place was doable on the setup I had and with wider wheels putting more rubber on the ground and stiffer suspension I feel top 5 is gonna be a thing. If I had the cash to do things perfectly I certainly would but just about every part on my car is used CL find.

Let me try it a different way then, for $700 bucks could you do a suspension system better?

In reply to Harvey:

NASCAR is a professional series- just like F1- you can win actual money.

Winning CSP gets you a jacket. BFD.

But more, the idea that one should not run a class because they may not want to spend the money- THAT really makes me mad. You even said that.

The idea that one has to have money to even TRY is very off putting. One of the many things that has put me off of racing, when I had done it for quite a while.

And that's why I think it would be really fun to try to make a challenge car that get get into the trophies. If I were still racing, and if I really wanted to deal with the SCCA- the latter of which I was put off of back in 1995.

I don't think it's good advice here on GRM to tell someone:

If you don't have money to spend then don't do CSP

$700 for a good CSP suspension? Can you rebuild shocks at home?

In Southern California all the CSP cars are gone. The amount of effort to keep them running based on how hard they were on everything that made them fast was profound. Extremely fast and brittle. Fuelled but lots of money. Just like a race car.

Co-driving was on the table at $900 for two tires, no you can't keep yours after the event and half the cost of broken parts. He provided the required labor. And add consumables.

I am now driving a 1995 in E Street, I'm sold.

If you can walk up to your car and cut the fenders, go for it.

Keith Tanner wrote: I've seen a National level CSP Miata up close, and it's the obsessive attention to detail that stands out. A tiny alternator. Drilled out brake rotors. Extensive dyno testing to determine the ideal length for the pre-throttle body intake tube. Like everything, you can substitute effort for money - but it's a highly competitive class, so if you're not spending the time/money, you'll lose to someone who is.

The Davis car is like that and it's not all about the car either, Billy Davis is a hell of a good driver. If it was just the car then his father Bob would be placing right next to him in the class at nationals.

The Davis car started out as someone else's competitive CSP car and then Bob and Billy went over it with a fine toothed comb basically breaking it down and building it back up again with the best parts they could get to the limit of the class. So, you're dealing with a lot of time and a relatively large amount of money (relative to say street/stock classes) being put into that car as well as a lot of driver preparation.

The Davis car is probably putting down 140-150hp at the wheels on a well prepared and tuned NA motor, runs 11" wheels with a huge section Hoosier tire on a custom Penske suspension with the maximum aero allowed for the class and a custom OS Giken diff out back. It's maximal preparation at every level. The money isn't even the biggest factor.

I'm not saying you have to start there to get there, people do this sort of thing incrementally as well, but if you have any goal of competing nationally then you're just wasting money on a Spec Miata suspension. As RedGT said the Spec Miata suspension is pretty low end even for ST cars. I don't even see it being much better than the FM 2.5 setup as all you are getting is stiffer springs.

alfadriver wrote: In reply to Harvey: NASCAR is a professional series- just like F1- you can win actual money. Winning CSP gets you a jacket. BFD. But more, the idea that one should not run a class because they may not want to spend the money- THAT really makes me mad. You even said that. The idea that one has to have money to even TRY is very off putting. One of the many things that has put me off of racing, when I had done it for quite a while. And that's why I think it would be really fun to try to make a challenge car that get get into the trophies. If I were still racing, and if I really wanted to deal with the SCCA- the latter of which I was put off of back in 1995. I don't think it's good advice here on GRM to tell someone:

If you don't have money to spend then don't do CSP

You obviously haven't done autocross at a national level. Mazda hands out contingency money for winning national autocross events. Hoosier and other tire manufacturers hand out free tires. At Nationals they hand out prizes worth a fair sum of money to the top podium winners. Mark Daddio has 4 sets of free tires in his garage after last year. That's about $4k+ worth of tires.

Think what you like, but it's the truth. If you only have $700 to spend on a suspension setup then CSP isn't your class. Like I said though, it's not a big deal unless you have ambition to compete at a national level event. If you just want to fool around locally then you can do whatever you want and that seems to be what KyAllRoad is talking about. Also I said that right after what you are now quoting out of context.

me said: If you don't have money to spend then don't do CSP. If you're just looking to have fun and be in CSP then do whatever you want.

The car I've seen was run on our dyno a few times. In 2011, it was 145 rwhp. And of course the driver counts.

How about a $420 Ground Control conversion for the Tokicos in the 2.5 setup? That's probably the best bang for the small buck upgrade.

Keith Tanner wrote: The car I've seen was run on our dyno a few times. In 2011, it was 145 rwhp. And of course the driver counts. How about a $420 Ground Control conversion for the Tokicos in the 2.5 setup? That's probably the best bang for the small buck upgrade.

I like this suggestion for an on the cheap upgrade. Can the Tokicos keep up with a heavy spring rate?

You're not going to want to push them much past the 425 lb front springs that come with the Ground Control kit, but they'll do it. If you want 700 lb front springs, you'll have to spend money on the shocks or revalve a set of Bilsteins yourself.

On that note, Keith, is there any chance FM has a FRONT shock dyno of KYB AGX adjustables, from back when you sold those rather than the tokicos?

SP is a money pit. see the pic next to my name....

You can trophy at nationals with a economy setup and good driving, but like Keith says. Pay attention to all the details. There is a lot out there to gain that little bit of power, get that little bit of extra weight off.

I would look at what you have to spend on suspension and do a lot of research. Good shocks can help out loads, but they can cost a lot of money.

Others have said better on the setup for you.

RedGT wrote: On that note, Keith, is there any chance FM has a *FRONT* shock dyno of KYB AGX adjustables, from back when you sold those rather than the tokicos?

No, when we sold those, shock dyno charts weren't cool. I can tell you that you can either have good ride quality or sufficient damping, but not both.

In reply to Keith Tanner:

Yeah, based on a rear plot I was able to find, ride quality is gonna suck on sharp hits. But ignoring that, do you know what spring rate the fronts are capable of controlling? Would save me the trouble of shipping a pair to my brother with a dyno.

I ran spec Miata take offs on my daily Miata for years and auto crossed with it many times. My rates were 700/225 and I think I could have gone a bit stiffer in the rear maybe 250 or 275 but as stated by keith, the bilsteins are alright, you probably won't be national level but local it's usually fine but that's only after they have been revalved. Honestly if I was to do it again I'd use konis revalved to hold the heavier springs. Btw they seem stupid heavy but where I lived the roads suck and the venues we raced on we're not smooth but I never ever thought it was too stiff. My kidneys are still in the right location too