Hello - Also posted in Suspension forum but perhaps this is a better place-

So about a year ago last October, I found myself the owner of a 1999 NB Miata with a fairly extensive list of mods, not the least of which was a full Flying Miata FMII with all of the upgrades. It has FCM bilsteins, 500# front springs, 350# rear with 1 1/8" front bar and an 11mm rear. It made 278 RWHP on a local dyno, it drives great and puts down power fairly well( other than violent wheel hop on launch) with the help of an OS Giken rear diff. Wheels are 15x9 6UL with now 4 year old 225 Hoosier A7 front and rear.

I had previously been autocrossing my air cooled 1988 911 carerra, and enjoying it, until I had a ride in a well prepped NA with a turbo and ABS.....

My driving improved immensely during the first season in the Miata. I was regularly a runner up for FTD, and the car was alot of fun but PAX tells a different story and it seems like I should be alot quicker than I am if I really want to be competetive. I know there is still alot of room for improvement with my driving and I'm working on that, but I also know that the car is under prepped for SSM and I want to make a few tweaks and need some help deciding on whats next. As far as the current set up, the car stops great, turn in is crisp, and mid corner grip is excellent once the car takes a set. Corner exit the back end tends to wash out and I'm finding it hard to go faster due to the oversteer at the limit.

Tires are due for replacement, so I am thinking about also making the move to 11" 6UL's and 275 A7's, but I feel that I may be under sprung for the level of grip that would provide.

This is where I am at a crossroads. I do not want to re invent the wheel and start over and replace everything, so whats the best plan? Can the current set up handle the increased grip 11' wheels and 275's would provide? Should I make the move to a street tire like the rivals for the slightly more favourable index? Keep the 15x9's and just bump to 245's?

I'm hoping that with the help of the hive I can drill down and come up with a plan to make the car more capable as my driving improves and start to PAX better that I currently do.



Thanks for any feedback

 

You will definitely need stiffer springs if you go the 15x11/275 route. I struggled to keep the front tires from getting chewed up with less than 1000lb front springs. If you aren't running aero, you can get away with less - probably in the 700-800lb range.

 

The 275/11 combo will require a wholesale replacement of your current setup. Sorry for the reality check.

We would start you with 1000/500 rates, 54106 front, stock rear sway bar. ELBJ, urethane suspension and diff bushings. Axle hop upon launch is the control arms twisting and unloading. Stiffer rear control arms will help.
The shocks will need to be revalved. If they are not shortened already, cut 1" off each body. 245 Hoosiers are best on 15x10. Even with 245's, you would want basically this same setup.

 

Thanks, I expected that would be the case. What would the budget be for that entire set up minus tires? I think perhaps selling the FCM set up as is along with the 15X9 6UL maybe a better option than cut /re valve? I'm quite certain all the bushings are already poly in the car with the exception of the rear diff which I think are Mazda Comp.

 

You'll have to shop around, many options. We sell pretty much everything you need for that setup but we aren't the only source. Easy button is our BGK (Big Grip Kit).

 

Decide whether you want to be competitive in SSM, or if you want to just go faster and enjoy yourself. There is some overlap, but if you want to be competitive in SSM, you're going to have to reinvent the wheel.

FYI, the 2017/2018 national SSM champ is a member here (TNTUBA). He has a build thread that you should absolutely read.