PART NUMBER: 61-1847RF
The BEST RF Springs, the EASY way to lower your MX5 RF correctly! These springs result in about 1 inch of lowering, rates are about 20% stiffer than stock. These are made exclusively for Good-Win Racing for the RF version of the ND Miata to work with stock shocks and have heights and stance work out correct for the RF version (most OTHER springs not calibrated for higher rear weight of RF end up with rear settling too low eventually and ugly reverse rake jokingly known in the forums as the 'speedboat' look). Rates are specific to the RF version, adding a little more rear spring rate to balance the car correctly with the extra rear weight of the RF version. Detailed specs below:
Stock heights on our ND were 14.25 to 14.75. Lowered heights with these springs approximately 13.5 inches front, and generally a bit over 13.5+ inches rear (measured car empty center of wheel up to fender lip, car levels once people are added since driver and passenger are almost sitting on rear suspension). Note if you add our KONI SPORT shocks they are much lower pressure because of twin tube design as compared with factory monotube and result with KONI shocks will be ANOTHER half inch lower than what we list here. 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.
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. Our team works with Progress on each Miata application spring, and with nearly a decade of working with Progress we know the result will show the quality and consistent performance that we feel raises the cornering joy level of the ND platform to a new level.
STOCK spring rates are 156 front for all models, and 80 to 100 rear.
Progress Spring rates 185 Front, 135 rear.
These MX5 RF springs feature increased spring rates for upgraded handling capabilities. These springs are designed to work with OEM shocks and bumpstops but will benefit further from using high performance shocks such as Koni Sport shocks. 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.
-All spring kits are powdercoated metallic gray.
-Drop amount varies by 0.25" depending on shocks used.
BRIAN'S APPLICATION NOTES: These are a great choice for those who want to replace the soggy factory springs to take out some of the crazy factory body roll, and improve handling, without dropping the car a lot. Lean on them in the turns and you will find the car is 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 the springs provide, combine these springs with our KONI SPORT shocks. For those who want the car even more flat in the turns, combine these with our Sway Bar Upgrades. I recommend our SHORT BUMPSTOPS with these springs for best ride and handling.
Shown below on our own 2017 RF on factory standard shocks and Progress Sways AND our short bumpstops.
INSTALL NOTES: As with the NC, so it also important with similar ND 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. 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 is so similar that same rules apply.
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).
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.
Pictures ABOVE are on stock shocks, picture BELOW is what you get when you add our KONI SPORT Shocks. Stock shocks are monotubes, the Koni Sport shocks are lower pressure twin tubes, result is the car settles lower than before, now about 13 inches front and about 13.25 rear (about half an inch below what we were with our RF springs on stock shocks).YES, works on 2019 ND2 and newer, with ALL factory shocks, example below is a Club 2019 ND2 RF with factory Bilsteins:
I had these Progress RF Springs installed along with the RoadsterSport ND Sway Bar Combo about a month after purchasing the car. As the other reviews mention, they drop the car about an inch. Prior to install my drivers side rear measured about a quarter inch or so lower than the front, and that didn't seem to change after the drop. No biggie.
Along with 17x8 +45 Advanti Storm rims, sways on stiff, a little track camber, and 225/45 Falken 660 tires, I took the car to Buttonwillow Raceway and ran the standard CW13 configuration. The brakes underperformed so I wasn't able to go quicker than 2:05, running mostly 2:06 to 2:08 through the day, but there were no issues with the handling at those lap times. I doubt there would be any problems going a few seconds quicker.
There was no rubbing into the on-camber corners like Off-ramp or through Riverside, and no floating on the slight off-camber Cotton Corners and over Phill Hill. I ride the rumble stripes and hop curbs through Cotton Corners, Bus Stop, and the Esses, and the car never got unsettled. It transitioned very well, loaded smoothly, and leaned only enough to give you a sense of the corner.
I'm sure Koni's would provide less roll than the stock Bilstein shocks, but the ride to and from the track was great. Stiffer than stock but forgiving, especially when back on the stock wheels and tires. These springs work well for a RF that should only see 2-3 fun, non-competitive track days a year. They provide a great middle ground between the squishy stock ride and a harsh race-car ride.
Just get these. Best bang for my buck improvement to my 2020 RF GT with the stock bilsteins. Ride and handling much improved with literally no drawbacks. Dropped one inch.
After I installed GWR compete street exhaust combo, I was emboldened to take on this install myself and it went great. Took all day but half of the time was fiddling with the spring compressor to figure out how to use it properly. Get the harbor freight nicer one piece compressor. Still cheap and was easy to use once I figured it out.
I did manage to strip one of the studs on a front top hat using a cheap torque wrench. Get a decent one.
I had already added anti-sway bars to minimize the (atrocious) body roll that I never expected to have to deal with in a Mazda MX5. After the improvement with stiffer bars, I decided to try to go a conservative (further) upgrade with these springs after also considering the more competitive offerings for autocross. At the same time, considering doing the work myself, I decided to take advantage of the price reduction of the Koni Sport shocks and add them to the upgrade rather than risk a much more aggressive spring change. This was a change mentioned as an option on the write up with Brian's notes. Koni Sport shocks include instructions that are easily misinterpreted- suffice it to say that their note about using the TOP setting for the height adjustment being used when adding LOWERING springs resulted in just what they said- normal ride height after installation- even though the Progress Springs write up IMPLIED a drop of about 1 inch. The mistake I made resulted in having to REPEAT the entire job a second time- this time(after talking to a Koni Rep)I was told that the change in shock pressure from the factory shock was accounted for by using POSITION 2. All my fault, two different products and confusing instructions led to a delay and a repeat of the work.AFTER correcting this mistake, I achieved the same drop and results. It looks great, feels VERY firm and makes me think the 20% spring rate increase is augmented by the very much stiffer Koni shock so that I would have regretted going with any stiffer springs.
The height drop is not that much, it does look better, BUT when you drive it.
Car should have come with these springs from the factory.
This should absolutely, no doubt be the first thing you do to the car.
The ride is firm but not harsh, and the grip and the feel are massive gains.
Just put these springs on yesterday and it lowered my car about an inch. Such a huge improvement in looks. I haven't had a chance to test the ride thoroughly but what little I have it seems to be sticking better to the road (not sure how much of that is a placebo effect). But the change in ride height is worth it alone.
I had the Progress Technology Springs for the RF installed last week with the alignment completed just the other day. I wanted to reduce the wheel gap and reduce the amount of body roll. The ride height changed from 14"-14.5" to 13.25"-13.5". The change in feel was immediate. The car felt more planted and the body roll and front-end wandering was noticeably reduced. The impact on ride quality was modest. There is a bit more harshness and impact shocks from broken pavement. The ride quality is still excellent for such a small car.
The alignment really brought everything together. The car tracks straight and feels so much more planted now versus new. I was so cautious about changing the suspension on a new car. While originally driven by wanting to improve the aesthetics for getting new wheels, the improvement in driving dynamics was much more significant than I expected.
Just had these installed @ Rocky's Miatamotive. Great Guy, really knows his Miatas. I'm pushing 50 & really didn't want a harsher ride than stock. The Miata GTS is soft/smooth over bumps & imperfections and while that's fine for touring, in harder driving it really got unsettled. "Sloshy" is a word I'd use for twisty road manners. The Progress Springs combined with the GWR Bump Stops have nicely settled the car down. Road imperfections ARE slightly "sharper" but not harsh or unsettling. The car now sits right & feels much tighter. When we picked it up from Rocky's my wife commented "Yup, its lower" and my butt actually noticed the difference in the drop into the driver's seat:) This car is a treat to begin with & these springs really are icing on the cake. Good Stuff!!!!
Just installed the RF Progress Springs using Rocky's method on my 2019 GT, loosened ALL bushings front and rear. I figured I'd have to get an alignment anyway so may as well.... After a drive and plenty of speed humps ended up at 33cm/13in front and 33.5cm/13.2in in the rear. Even each side! I'm very happy with the result. Ride is comfortable, not too low. Just right. Less bounce! Hello from Australia!
Lowered the Miata about an inch and a half, followed all the recommendations by Good-Win-Racing. Ride is still comfortable, drop is noticeable, and feels much flatter going around turns. Much more lateral G-force felt in the cabin. Most noticeable, the nose doesn't dip and rise when shifting any more.
These are the springs that it should have come with from the factory! Solves ride height and even adds a bit of roll stiffness. Ride is not negatively impacted. "Bilstein jiggle" is still present though. May consider Koni's and Roadster sport springs at the 30k mile mark.
Lowers 1 inch as stated, nothing else changes. Reduces the gap between tire and fender by approximately 1 inch which is barely noticeable. Installed with short bump stops which probably is not necessary unless you go lower. If you want less gap, go with a different spring or maybe stick an 18 in wheel with wider rubber.
I waited until I had 500 miles on my 2019 RF GTS after the Progress springs (and new bump stops) installation to post my review, and I couldn't be happier. I got just the drop I wanted - an inch - and that's remained consistent. The lowering along with beefier sway bars took almost all the body roll out, improved both handling and ride quality, and looks killer.
Read more at my blog: https://lifebeyondpolitics.blog/2019/04/02/my-mx-5-mod-9/