I'm not planning on racing, but I think it's likely the next owner might.
Without getting into a deep reading of the entire rule set, What is a list of the primary changes and modifications that define a Spec Miata?
Are they stripped racers? Modded street cars? Do they have creature comforts like AC and radios? What are the typical mods for a competitive car?
I'd like to do the major mods now as I build the car, so a swap later would be super easy if a future owner wanted a Spec Miata.
The rules are very exact on how the roll cage is built, wheels and tires, and the suspension package. The only way to really get the full answer is to read the GCR for your sanctioning body. Small and seemingly stupid things like removing the washer fluid bottle will make the car ineligible. There are hundreds of "almost" SM's out there that were built by people who didn't read the GCR, and consequently won't pass tech.
Also worth noting that the SCCA and NASA GCR's are similar but not exactly the same. Also also worth noting that the chosen mods aren't necessarily to make the cars perform better, but to make them more competitive with one another. When interpreting the GCR, IIDSYCTYC- "if it doesn't say you can then you can't".
If I was starting from scratch, step one would be installing the most modern, GCR compliant roll cage possible from an experienced SM shop. Make it forward compatible with floor drops and all the stuff that tall drivers require. This generally involves gutting the doors, which means the car will no longer be weather tight and must live in a trailer or garage. All the safety stuff needs to be integrated to the cage, expect to go $5-6k out of pocket just on this stage. Now you see why it's hard to do a "halfway" race car.
Also, way easier to learn by seeing first hand. Go to a local SCCA race weekend, introduce yourself to a few of the drivers and ask them if you can look the cars over.
The "major" mod to a Miata for SM duty would be stripping the interior and putting in a roll cage. That includes removing the dash and gutting the doors. Everything else is relatively simple.
Eibach #700 springs up front, and #325 springs rear, Penske spec shocks, a five or six point harness, some 15"X 7" wheels that weigh at least 13lbs., and some spec tires will get you the rest of the way. A proper exhaust (most used Springfield Dyno when I raced SM) certainly helps.
Depending on what car you have, there can be other things you have to do, such as NA1.8's have to change out the 4.10 final for a 4.30, NA1.6's can run top hat perches that lower the car some and you get to run an aftermarket air cleaner, whereas later cars have to run a plate restrictor depending on year.
Remember that just because the suspension kit is "spec" doesn't necessarily mean it's the best choice, just that it meets the requirements.
I built my first track car with all Spec Miata parts, but since I wasn't actually competing in Spec Miata, it didn't always work the way that I wanted it to. I built my next car very differently.
Plus, there's stupid stuff in the rules, like if you put the washer on this side of the sway bar bracket it's a washer, but if you put one on the other side of the bracket so your sway bar doesn't bind, then SCCA calls it a spacer and it's illegal.
There is no getting around reading the rule set if you want it to comply.
In reply to Woody (Forum Supportum) :
The Penske shocks are a huge step up from the Bilsteins that were used for years and years.
A Spec Miata is a stripped out race car that can technically still be street legal, but you'd only drive it on the street to prove a point :)
In reply to Keith Tanner :
That's good to hear. I had the Bilsteins.
Ok. Thanks guys. I've learned enough.
That's not what I want to build.
Feels good to have some decisiveness in my life! Haha!!
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