Good-Win Racing Mazda Performance Parts

RoadsterSport ND Springs


Front Rate 300, Rear 200

Miata MX5 2016-2017 · Suspension · Springs

Part Number: 61-1847ND

Application: 2016-2017

Price: $269.00


RoadsterSport ND Springs
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Serious performance springs for the serious street enthusiast, ENOUGH RATE for Canyons to Autocross to Track! We took a Top Time of Day with these on Koni Sport shocks at autocross event with 100+ competitors.

Tested on our ND Miata and Fiat 124 (shown here on our own Fiat 124 and a customer ND, both built on same ND chassis in Japan, same lowering effect). Stock heights were 14.25 to 14.75 (measured center of wheel up to fender lip). Lowered heights with these springs approximately 13.75 on stock shocks, 13.25 as shown here on KONI Sport shocks which are lower pressure than stock shocks and therefore settle lower. Important to understand these are really too much rate for base trim stock shocks, the stock Bilsteins on the CLUB version handle these well, ideally used with the Koni adjustable SPORT shocks with our short bump stops. Your results will vary depending on which shock you use and the age of the shocks, as shock pressure declines over time the car will settle lower.

Numbers here are for SOFT TOP version of MX5, these are not compatible with the RF chassis. With the additional weight of the RF the heights are incorrect.

These Miata springs feature increased spring rates for vastly upgraded handling capabilities. Certified high-tensile SAE spring wire materials. These Miata springs are cold-wound on modern CNC coiling machines, then stress relieved, pre-set, and shot-peened for maximum durability.

Rates 300 Front, 200 rear.
-All spring kits are powdercoated.
-Drop amount varies by 0.25" depending on shocks used.

BRIAN'S APPLICATION NOTES: My new favorite simple formula for around town fun that can hit the canyons or autocross/track the weekends! Enough rate to make the car MUCH more flat in the turns without making the car harsh riding. Started this project with the idea of making the perfect springs to match with KONI Sport shocks, though they also work well with factory Bilstein shocks in CLUB editions (too much rate for the NON-Bilsteins). These are a great choice for those who want to replace the soggy factory springs to take out much of the crazy factory body roll. Improves handling massively without dropping the car too much, just half inch of lowering on bilsteins, total 1 inch of drop if you also add our KONI SPORT shocks. Lean on them in the turns and you will find the car is MUCH flatter and faster because the tires stay flatter to the ground instead of rolling onto the sidewalls as happens with the soggy factory springs. For those who want MORE THAN HALF INCH DROP than these springs provide on the Bilstein shocks, combine these springs with our KONI SPORT shocks which are lower pressure to total about an inch of drop.

INSTALL NOTES: Important not lock down the bolts to the suspension after install while the car is suspended in the air with the suspension fully extended. Bounce it on the ground, then give it a drive around the block with the bolts just snug so you get it to settle before you torque everything ON THE GROUND. Many shops will NOT know to do this...SMART CUSTOMERS PRINT ALL THIS PAGE FOR THE INSTALLER! See details in our forum installation section from NC application, thread is titled: "Spring Installation, Mazda Workshop Manual Notes" and factory TSB notes below. Once you do it right, drive it 500 miles and then do it again (which usually results in another quarter inch or more of lowering)....and then do the alignment. ROCKY'S TIPS: Our head mechanic Rocky has his own method that seems to work even better than the factory TSB. Once he finishes install at each corner he jacks up just that corner with BOTH UPPER AND LOWER LINKs loose, so the full weight of the car is compressing just that corner, then he torques the bolts...and he finds car will still settle with 500 miles but usually only another 1/8th inch.

Below is NC service manual notes, but design with ND/Fiat 124 is so similar that same rules apply.



Picture below is with KONI SPORT shocks.

Alignment depends much on what you do with the car. Assuming no autocross or track use, for pure street driving my suggestion is:

Front Camber -1.2
Toe IN 1/32nd per side (some shops call this 1/16th 'total' toe in).
Caster 6

Rear Camber -1.2
Toe IN 1/32nd per side
Racers will take much more camber and zero toe all corners (and usually full coilovers instead of just these very mild street springs). Autocross customers will toe OUT the front, track users usually toe ZERO front and rear.

*** Product images may differ from actual product appearance ***


First I want to again thank you for working with me on this muffler. I have almost 100 miles on it now, and it has a nice mellow sound. a little Bass, but not too much. A little louder than stock, but not too loud. Plus it is nice inside the car with the top up. I am happy so far I bought this one.

I belong to a local Miata club, and am very active with it. When Spring comes I will tell everyone how much I like the muffler, and how great you are to work with. Maybe I can get some extra business for you.

-- Bill

Thanks for such speedy and great service.

-- Richard H.