Quick Miata suspension question, will an SM suspension from a '90 Miata fit in a '96 Miata? I found a set of used Bilstein/Eibach package from a '90 Miata on the internetz that I am considering for my '96. Also, will Bilstein with 700/325 Eibach springs too much for a Miata used mainly for autocross and possibly some track days?
It's hardly driven other than to and from autocross events and some fair weather driving. Last year for instance I drove it less than 1,500 miles.
Yes it will fit, I don't know about the spring rates.
From what I have read, the rates your looking at are close to what a competitive STS car would run. Doable on the street, but harsh I would think.
Unless the bilsteins are revalved, those will likely not be the ideal setup for your needs.
Yes, it'll fit.
But even fast Spec Miata guys don't run an unmodified Spec Miata suspension. They're underdamped. You can do better for the money if you're not constrained by that particular rulebook.
I'm running 550/350 spring rates on revalved Bilsteins. Harsh but driveable on the street. Fun dodging the cones :)
Update - I decided to pull the trigger and bought it. It came with the AWR threaded perches and Eibach sway bars. The thing is it didn't come with bump stops, shock mounts, washer, nuts (basically the hardware to install it). I saw that on FCM website they have the Spec Miata shock mount/bump stop kit (i.e. FCM-MT-KIT-SM). Supposedly this kit is ideally combined with '99 mounts. My question is, if I but this FCM kit and '99 mounts, is there anything else that I need or that's it? Also, is there a cheaper alternative out there?
My Miata came with an FM rear shock mount, can I reuse it? It was for KYB AGX shocks, not sure if KYB AGX and Bilstein have the same shaft diameter.
Thanks for the input.
If you want to mount NB upper mounts on a set of shocks designed for an NA, there's a certain sway bar bushing you can get from Energy Suspension. Cut it in half and you've got what you need. You will need washers too. It may not be any cheaper than the FCM stuff. If you've got a Mazda Motorsports account, you can get the factory parts for next to nothing.
I believe those Bilsteins use the same 10mm shaft as most other Miata shocks (Konis and exotica excepted). So they should work fine with the FM mounts. If not, we have different bearing inserts for 12mm shocks or you can remove the inserts for 9/16" Penskes.
Thanks for the input Keith, maybe I should rephrase the question 
if I currently have the old FM suspension package (FM Spring and KYB AGX with FM rear shock mount) can I use the same hardware to install Bilstein shocks, Eibach springs, and AWR threaded collar (all from ex-SM car)?If I need to buy the washer and nut for Bilstein, where can I buy these items? Thanks all.
The mounts should work. I imagine the nut will be the same. I'd recommend doing a full inventory of what you have and what you need.
