Mazda Talk Forums

matthew-m wrote: I was under the impression I have Eibach springs, but I have no idea.

Just FYI, you most likely have Eibach 65-mm, 8-inch main springs in front and Tein 90- to 70-mm, 8-inch tapered springs main in the rear, You probably also have Hyperco helper springs front and rear.

I used Brian's delrin adaptors for straight springs, but I've recently switched to using offset adaptors 3D printed by auto-X-er to provide additional damper-to-spring clearance.

matthew-m wrote: Sway bars are stock and the car was aligned and corner balanced.

You might also need to adjust your sway bars. With your springs and sways, I estimate your front roll couple at 61% or 62%. For comparison, find my car pretty balanced at 71% using the same spreadsheet. So, that means you have 10 percentage points more of your roll stiffness coming from the rear than I do. That should give you some decent oversteer. The easiest thing to try is to remove the rear sway bar. That takes literally 10 minutes, and you can do it with 1 wrench and 1 ratchet without jacking up the car. (Running without the rear sway is not unusual.) That my solve or at least improve your situation. If it makes it somewhat better, then we know we are on the right track; you can then add a stiffer front sway and/or stiffer front springs.

Given that your bounce frequencies are a little out of whack, I'd suggest some combination of much stiffer front sway bar and either softer front spring or stiffer rear springs.

skeeler wrote: Given that your bounce frequencies are a little out of whack, I'd suggest some combination of much stiffer front sway bar and either softer front spring or stiffer rear springs.

OK, having played with the numbers a bit, here are my suggestions:

If you want to go slightly softer than your current setup, then go to 250/224 springs and red dot/green dot sway bars.
If you want to go slightly stiffer, then go 300/280 and red dot front sway with no rear sway.

Does your car have an LSD? In other words, is the rear sway bar green dot or blue dot?

But like I said, try just pulling off the rear sway bar first, to see if that helps.

Skeeler,

Thank you for the suggestions. I will probably go to a softer front spring when I replace the rotors and pads. I'll give Brian a call when it is time to place an order...

I have no idea what you are describing in terms of the color dots on the sways. Yes, my car has the LSD that was included with the sport suspension option. I will go ahead and try dis-connecting the rear sway when I get new tires.

Matthew

Mazda's OEM anti-roll (sway) bars have a spot of color painted on them to identify their rate, since it's hard to tell just by looking. RX-8 sway bars fit the NC, since it's built on an RX-8 platform. Here are the colors for the two cars:

Green front: NC soft top
Green rear: NC w/o LSD

Blue front: NC PRHT
Blue rear: NC w/LSD

Red: RX-8 with normal suspension
Yellow: RX-8 with Sport supsension
Orange: RX-8 R3

Hmm,
I see two issues here, bad shocks from the OP & too stiff FCM springs & shocks.

I just removed Mazdaspeed PRHT springs & NC2 Bilsteins from my wife's 08 (NC1) GT soft-top & installed a set of NC2 front springs, Koni's w/ a set RX-8 red front w/ yellow rear sway-bars. They just work well for a DD and are well balanced at the limit.
The NC2 (09 & newer front springs) have a lower front ride hight then the NC1 (06 to 08) front springs, the rear springs are the same. Mazda makes 5 set's of springs for the MX-5 per my Mazda parts man. Depends on what car you have and what suspension package & with & with out L/S diff.
I will say I was totally shocked on what Koni's & sway-bars do for this car. It's not going to the track or autocross, it's just my wife's DD.
My word of *advice* is buy Koni shocks & a good set of 215/45-17 or bigger All-Season tires.
I also installed a set of Nitto INVO's on my wife's car and they are great.

AZ

Konis and fcm bumpstops should be arriving soon

Can I just drop the components off at a regular mechanic and they should be able to install without direction ?

I'm asking because Miata.net posters seem to have issues with the install process.

The directions that came in the box are VERY minimal.

Thanks in advance.

Average mechanic without the mazda workshop manual will likely not get the final steps right....but we have all that in this forum in the instructions section.

Ok. Since I'm only installing the Konis (no springs), the mechanic only needs to tighten the bolts once she's back on the ground. I don't need the extra step of driving the car around the block before the tightening and then again after 200+ miles?

The procedure is the same. You have to remove the the same parts whether you change the springs or not.