spring rate suggestions

[zxtwou2]

ok, i need some input from those of you who know autoX better than i do...which isn't hard really.

i'll most likely be going the route of getting some GC coilovers, since i can chose the spring rate when i buy them, and i'm too broke to get K-sports. right now i'm on Sprint springs...which are 5 years old to boot. they are 1.8" lower, and very slightly stiffer than stock, if at all. i get TONS of nose dive, and a lot of body roll.

i don't really want to go too much lower, 1.8" is plenty fine for me. i do want to know some suggestions for f/r spring rates. some people tell me rear being stiffer helps on cement, and front being stiffer helps on asphalt. at any rate, i was thinking of going with a 420 front, and 380 rear spring rate. is this a good start?

[STS-ZX2SR]

We bagan on 455/375 and the car was silly loose. Went to 550/375 and was much, much better...free and willing to rotate, but not snap-spinny.

The ratios are more important than the actual rates...and 420/380 seems kind of rear biased if you ask me.

What dampers are we using here, Tim? As for lowering...front LCAs should be level, not past, or you lose turn-in...it's easy to go too low.

Also, as for asphalt/concrete...tune springs for the one you do most and then use the RSB, which is easy to change, for the final icing on the cake.

[zxtwou2]

right now i have the 19mm swaybar, and can get easy rotation with a lift of the throttle on asphalt. but on the cement, the front would just dive in and slide. i got the rear to loosen up later in the day with pressure change (ended up running 41/35). also, i'm on Tokico s/r struts.

[zxtwou2]

also, i'll be doing asphalt more...the cement was at a very small local airport autoX

[STS-ZX2SR]

I'd caution you about 'over-rating' those dampers...they wont live long that way. The S/R (dampers) came with variable springs that were 300/200 at the high end, IIRC. Maybe try 350/250. That is a 1.4 ratio. Mine is 550/375=1.46 with our current setup...and again it's 'free' with the 22mm RSB on the soft setting. You can easily move up to a EGT 21mm or a Progress/ZXT 22mm 2-way RSB as well.

FWIW our setup is similar to Darryl Craig's (Mazdaracer) Protege...500/325, Quickor 24mm RSB. Will Kalman (STS EGT) ran 600/500 and had some uber expensive custom dampers to boot--thats about as stiff as I've seen. I am not sure how he got it to go as well with that high rear speing rate (and also a 24mm RSB)...but his car was very, very quick.

[zxtwou2]

are there any struts that will work with a 420/380....or even 450/350 setup?

[STS-ZX2SR]

are there any struts that will work with a 420/380....or even 450/350 setup?

We have custom Konis. They started life as "Reds" for a MX3. They were converted to "Yellows" by Koni. Fortunately they came with the car... This is pretty expensive...

I do not know if the 99+ Protege (BJ) dampers can be adapted to the BG chassis...I think I saw that they can...but the BJ swaybar needs to be used...or something like that. If so, there are plenty of choices (all seen at Corksport.com). Maybe snoop around at Mazda247 forums, in the AutoX section,and see if someone knows.

[STS-ZX2SR]

http://corksport.com/store/category/53hi/626-shocks.html

I have just been told that Probe/MX6/626 stuff works with little or no modification on MX3s--should translate to working on ZX2. Mazdaspeed dampers are designed for higher rates and are adjustable...

[zxtwou2]

i'll definitely be getting those struts! thanks!

as for spring rates...i just found my old 2002 Ford Racing catalogue...and the FR coilovers for the zx2 were 300f/500r. should i really be that much stiffer in the rear???

[STS-ZX2SR]

i'll definitely be getting those struts! thanks!

as for spring rates...i just found my old 2002 Ford Racing catalogue...and the FR coilovers for the zx2 were 300f/500r. should i really be that much stiffer in the rear???

It's gonna spin like a top unless you keep the OE 13mm RSB...that was the 'trunk kit' for SCCA SSC road racing...to compete with the ACR Neons.

Our 550/375 with 22mm RSB setup is still 'free' but not stupid-loose; I've also seen 500/325 used on STS Protege. I'd suggest that you look at similar F/R ratios using the stiffest spring that those front dampers will handle as the starting point...which I doubt will be 500 pounds, but certainly could be 400.

Its better to be undersprung than under-damped.

[zxtwou2]

so i should be safe with a 420/380? my biggest question i guess is how much different should the fronts be than the rear...and should the front be softer or harder? right now i'm running equal spring rates with a 19mm bar, and i have fairly predictable oversteer on throttle lift...but i have massive body roll.

[STS-ZX2SR]

I'd say try 420 and then someting in the low 300s--380 just seems to close to the fronts based on my experience. You can always run a 21 (Junkyard) or 22 (Progress) RSB too.

YMMV on the rates...and there are certainly those who'll say 'go big' in the back. All I can say is that our car was insanely loose with 455/375. The bump to 550 in the front has been the single biggest improvement we've made...its the F/R ratio moving from 1.21 to 1.47 was the key IMO. 420/285 would duplicate our ratio.

I can "see" the best-of-the-best STS cars now with our setup (I don't know of any actively running BG chassis cars in STS that would faster than ours), and we're likely just "learning to drive what we have" from having a Trophy-worthy car at Nationals...next year.

[paco_swava]

How about 650/650? That should rail! Haha

[STS-ZX2SR]

I expect that if all goe$ to plan, we'll have 700-750 in front next season (and a smaller Protege FSB)--but we need a damper upgrade to get there...and that is $pendy.