Get the heights RIGHT for your NC2 PRHT. Too many spring makers did not adjust their springs after NC2 MX5 arrived starting in 2009, the springs from those other guys end up with back end low and front end relatively high. That dreaded 'Speedboat' effect is avoided by these springs made specially for the 2009-2015 MX5, after a few thousand miles on our Project PRHT 2012 they settled to 13.5 front and about 13.8 rear (your results may vary depending on which shock you use and the age of the shocks, as shock pressure declines over time the car will settle lower).
The engineering staff at Progress has decades of experience in the design and tuning of performance suspension systems, including CART/Indy Cars, IMSA, SCCA, NASA, and SCORE competitors. These MX5 springs reflect their ability to develop a successful blend of appearance, handling capability, and ride quality.
These MX5 springs feature increased spring rates for upgraded handling capabilities with reasonable rates to maintain superior ride quality. These MX5 springs are designed to work with OEM shocks but will benefit from using high performance shocks such as our adjustable choices from Koni and Tokico. Progress specifies only certified high-tensile SAE spring wire materials. Their MX5 springs are cold-wound on modern CNC coiling machines, then stress relieved, pre-set, and shot-peened for maximum durability.
-Front starting rate: 126 lbs/in --- Rear starting rate: 116 lbs/in
-All spring kits are powdercoated metallic gray.
-Drop amount varies by 0.25" depending on shocks used.
BRIAN'S APPLICATION NOTES: These MX5 Springs were chosen by Mazda for their limited edition 2007 MSR package that now dominates the SCCA STOCK CLASS! These are a great choice for those who want to replace the soggy factory springs, improve handling, without dropping the car a lot. Notice starting rates just a little stiffer than stock but once you lean on them in the turns 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 DROP than the half inch drop the springs provide, combine these springs with our KONI SPORT to reproduce that factory MSR package handling and stance for total lowering of about an inch. Shown below on PRHT in combination with factory Bilstein Sport Suspension shocks. We suggest adding our FCM Sport or Comfort bumpstops depending on your driving intentions.
INSTALL NOTES: It is important to 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. Most shops will NOT know to do this...SMART CUSTOMERS PRINT ALL THIS PAGE FOR THE INSTALLER! See details in our forum installation section, 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.
ALIGNMENT:
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 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.
Install below on Customer Paul Young's MX5 Club, heights immediately after install using the Rocky method explained above, 13.5 front, 14.0 rear.
And soft top version of Club, same Progress springs, same results of 13.5 front, 14.0 rear.
These are an evolution of same springs that Mazda sold in the MSR package 2007 MX5 that has DOMINATED the Stock/Street SCCA Autocross class for years. Take a ride in a fast MSR and notice how fast and stable an MX5 can be with these springs as part of the package that includes our FCM stops and KONI Sport shocks and Progress Sway.
Customer Chip Barclay's Miata below with our Progress Springs, KONI SPORT Shocks, and our 17x8 Advanti Racing Storm S1 Wheels.