STF Suggestions

I found out I'm getting a decent tax return this year and I plan on doing some suspension mods to my M2. I'm definitely getting DDM rear bar. I'm torn between doing a full set of Bilstein B14s or getting CS dampers and RB springs. I've heard great things about the Bilsteins and the CS dampers but haven't heard much about the RB springs. Anyone have any info?


I will be daily driving my M2 so I don't want to go super low especially for the winter. I can deal with the harsh ride either may be.

Bilstein would be the way to go.

Better yet get them through Mazdaspeed which IIRC are valved better for the spring rates.



How serious are you about being competitive? Locally? National events?


I'm on a set of fabricated coilover housings with Koni road race inserts up front and Ford Focus KYB AGX rear shocks with 700/450 rates for daily driving. 550 rears when autocrossing. Experimenting with 700s in the rear at the next event.

No idea how far you're willing to drive to see what a competitive setup is like, but I'll be at the Metlife Stadium in NJ on May 1st with "Jasyatz" who has been through nearly every setup before he sold it. He'll be codriving my car at that event to help me further develop it.


Here is Jeff's build thread... LOTS of info in there, specifically for all the bolt on aftermarket suspension stuff, Bilsteins included.
http://www.mazdas247.com/forum/showthread.php?123834964-jasyatz-build-thread

Mine is in my signature.

I've had both so I'll give you my thoughts. Keep in mind I have CS front as rear bars as well (with both setups). For a daily driver, the CS/RB combo can't be beat. Ride quality from more comfy than stock to nice and firm. The bilsteins (I got mine for around $750 IIRC, not from mazdaspeed) will lower the car a bit more. The ride is substantially firmer, but certainly fine for daily driving if you're used to cars with coilover setups. Out of the box, the car feels a a tad bouncy in the rear. Handling wise, there is no comparison. Cornering with the CS/RB felt really good, but the bilsteins had me thinking my mazda2 now handles better than my track focused miata.

I swapped the bilstein rear shocks out for the CS units, and the bounciness went away. Driving comfort is now way better. The OTS bilstein rear shocks just don't have enough rebound dampening for the supplied springs.

If you can confirm the rebound is firmer with the mazdaspeed sourced kit, then that is likely the way to go. Otherwise, I'd recommend budgeting for the bilstein kit plus the AGX rears. Too bad CS only sells their damper kit as a full set.

Honestly if I had it to do over again (as opposed to doing it over and over and over again), I'd go straight for the BCs. Get them with a more favorable rate (350/250) which is about 25% more stiff than the Bilstein rates. The Bilsteins rode great, were awesome on the street, but felt really soft on course. The BCs (with the 500/550s) were fantastic on course but are definitely on the more "serious" side of daily/autox daily use. I tried the CS for one event, not really thrilled with them but I had other goals than just an improvement for spirited driving. Ran them with the stock springs so maybe that's where I felt let down. They do have a low cost of entry, but if you add in the cost of springs, you're 75% of the way to a full coilover with height adjustability and they ability to expand rates and set camber where you want it. The Bilsteins use the stock upper plate and although I built a camber plate for them (see my build thread for the instructions), but were a fixed camber solution and only adjustable by using bolts in the lower mount. Add the Camber correction kit to the Bilsteins and you're just about where the BCs can be had for. All in all I've had 8 different variations on my car and 4 completely different setups. After 13 times having the struts in and out, I got good at swapping them to say the least. Final time putting in the stock struts and springs took 2 hours including setting the toe.

Find a way to get to an event, meet or gathering where you can ride in or drive someone's car that has some sort of setup in it. This way you can decide what you like first hand and prioritize how deep into "full STF prep" you're willing to sacrifice daily driving comfort for.

I got the bilstein pss b14 and they are really nice and not jerky at all on street driving, but they are soft when you are racing in autox or at the track. Sure you can get stiffer springs but without shock adjustability, its moot.

Since you live in the northeast, I would go with coilovers rather than springs and shocks. You can raise the car up during winter for clearance and lower it again for the warm months.