vroomevo

iTrader: (22)

Evo Spring Rates
Name
Lowering Springs:
...................................Front.......... ........Rear.............drop

Eibach Pro-Kit:**....165lbs(2.9k)....140lbs(2.5k)....1.2f / 1.2r
Espelir ASD:............263lbs(4.7k)....319lbs(5.7k)....79 f / .79r
Espelir GT:..............308lbs(5.5k)....330lbs(5.9k)....1 .7f/ .98r
Ralliart:...................280lbs(5.0k)....307lbs (5.5k)....0.5f / 0.5r
RSR:**....................224lbs(4.0k)....280lbs(5 .0k)....1.4f / 1.4r
RSR Ti2000..............280lbs(5.0k)....336lbs(6.0k).. ..1.4f / 0.8r
Stock(USDM):..........180lbs(3.2k)....225lbs(4.0k) ......STOCK
Tanabe GP210:.......256lbs(4.6k)....319lbs(5.7k)....1.5f / 1.0r
Tein High Tech:**...196lbs(3.5k)....268lbs(4.8k)....1.4f / 0.3r
Tein S Tech:**........212lbs(3.8k)... 291lbs(5.1k)....2.0f / 0.9r

Coilovers:

APEXI PRO:..............560lbs(10.K).....560lbs(10.K)... .Adjustable
CUSCO Zero 1:........392lbs(7.0K).....280lbs(5.0k)....Adjusta ble
CUSCO Zero 2:........392lbs(7.0K).....280lbs(5.0k)....Adjusta ble
CUSCO Zero 2R:......392lbs(7.0K).....280lbs(5.0k)....Adjustab le
HKS Hypermax II:....392lbs(7.0k).....336lbs(6.0K)....Adjustable
HKS Hypermax RS....336lbs(6.0K).....280lbs(5.0k)....Adjustable
HKS Kansai Tarmac:.448lbs(8.0K).....448lbs(8.0K)....Adjustabl e
HKS Kansai Track:....896lbs(16.K).....784lbs(14.K)....Adjusta ble
HKS Performer:........392lbs(7.0k).....336lbs(6.0k)... .Adjustable
HKS PRO:.................672lbs(12.K).....672lbs(12.K) ....Adjustable
JIC FLT A2:...............560lbs(10.K).....504lbs(9.0K)... Adjustable
OHLINS FLAG L:.............ANy ..............Any ...............Adjustable
OHLINS R/T:.............250lbs(4.4k).....310lbs(5.5k)....Ad justable
Ralliart:....................336lbs(6.0K).....336l bs(6.0K)....Adjustable
Tein Basic:...............392lbs(7.0k).....336lbs(6.0K) ....Adjustable
Tein Flex:.................504lbs(9.0K).....448lbs(8.0K )....Adjustable
Tein SS:...................392lbs(7.0k).....336lbs(6.0k )....Adjustable
Tein RA:...................672lbs(12.K).....504lbs(9,0K )....Adjustable
Tein HA:...................504lbs(9.0K).....392lbs(7.0K )....Adjustable
Tein HT:...................896lbs(16.K).....672lbs(12.K )....Adjustable
ZEAL:.......................336lbs(6.0K).....280lb s(5.0k)....Adjustable
ZEAL Also:...............448lbs(8.0k).....392lbs(7.0k). ...Adjustable

** = progressive rate

why lowering spring/stock springs are stiffer in front and coilovers are stiffer in rear?

will it be OK to i put stiffer aftermarket spring in the front and softer stock spring in the rear?
:roll:

vroomevo

iTrader: (22)

anyone know why???
help me out!!

Darwinator

iTrader: (8)

Softer spring in the front would increase understeer because of the heavy front end. A stiffer rear end would make it unpredictable.

'ringmeister

iTrader: (25)

-i think it is because most of the JDM coilovers are designed around the JDM evo7/8 which have acd/ayc, front LSD, etc. these systems actively reduce understeer, so the spring rates appear to be matched to the (more, or less) to the f/r weight distribution. '03 USDM evo would seem to benefit from stiffer springs at the rear to increase weight transfer to the rear, and reduce understeer. At least that is what i hope because i have just gotten a set of ohlins w/ 350 front, 450 rear spring rates.

markdaddio

iTrader: (1)

I believe that it has more to do with where the front and rear roll centers go as you lower the car, requiring reletively more spring rate at the front as you go lower.
Mark

hi_nrg_fizzix

Mark,
Sorry to bother you, but you seem to have a wealth of suspension wisdom. I was wondering why a lot of the custom tuned coilovers for USDM EVOs like, RRE JICs, Ohlins, etc. use a softer spring rate in the front and stiffer rate in the rear, unlike the out of the box JDM setups, which generally have stiffer rates in the front? Thanks --John

2GDSM

stiffer rear springs provide more oversteer. Even the evo has modest understeer from the factory. Obviously less than almost any car you can buy, but its still a liability issue and I'd be willing to bet they add some understeer to keep drivers out of trouble. Aftermarket springs are more designed for look and ride comfort. Real coilovers are designed for performance so they add in extra roll stiffness.

markdaddio

iTrader: (1)

John,
I have not done an in depth analysis of the exact roll center movement in an evo yet, but generally speeking, I can tell you the following basics. Basically, the spring rate required to limit body roll to a desired level is based on the cg height, and the roll center height at each end of the car. The farther apart those become, the more spring rate and bar rate you need to keep the same amount of body roll at an equivelent cornering force. The Evo has a strut front suspension, which by design causes the roll center location for the front of the car to drop more than the amount of vehicle drop. The lower you go, the more drastic this would be. The rear suspension however is multilink, and in that type of setup, there is much more control over the rate of roll center height change than in a strut setup.
As to your specific question regarding why the JDM setups are generally stiffer than the custom tuned american setups I will offer my humble opinion. I will start by saying that I am currently setting up my evo for SCCA solo competition, and I can tell you from experience that the current practice of running 350-450 front with 450-550 rear springs, and a bigger rear bar is not an ideal track, or autocross setup for a lowered car. I believe those setups are good, better than stock, street setups. The bulk of these setups are sold to people that primarily drive their cars on the street. I believe that for ultimate performance, the evo should run with somewhere in the 700 to 800 lb/in spring rates in the front, and 650 to 750 in the rear. There are several problems with running that much spring rate on the street. One is that suspension travel in droop is limited, the other is ride quality. It becomes fairly expensive to make a shock that will work with these high spring rates and not totally beat up the occupants of the vehicle. The droop travel issue is a bit more complicated, but basically an 800 lb/in spring will only compress half as much as a 400 lb/in spring with the same load applied. This means that the spring would reach full extension in half the distance, hence half the droop travel. It really comes down to what you want out of the car, and what you are willing to spend.
Sorry for the long response. I won't go into the bars, as that is a discussion in and of itself, and there is already a thread in the motorsports section that goes into that. I hope this helps a little.
Mark

EVO8LTW

iTrader: (41)

I guess I was on the right track with Tein RAs. I just pulled mine off though because I'm going to go back to autocrossing my other car and prefer the ground clearance and ride quality of the stock set up for pure street use.

For you guys that don't know who "markdaddio" is, he's probably the best autocrosser in the country. In addition to multiple national SCCA solo championships, he's also a two-time winner of Mazda Rev It Up (http://motortrend.com/features/news/...up/index1.html). He's so good that other nationally competitive autocrossers refer to him as the "alien."

He's also a great instructor. I learned a ton from him in a McKamey (now Evolution) autocross school when I was first starting out. I still remember that experience vividly. What an eye opener when he took the controls of my car!

nils

iTrader: (56)

ha!
that is what I thought... I remember reading about Mark in GRM.

good stuff!!!

vroomevo

iTrader: (22)

so howz 263lbs front / 225lbs rear sounds like compare to 263 lbs front / 319 lbs rear?
i know...compare to coilovers, it's a small number but want best out of spring setup for now.
thanks for the reply

'ringmeister

iTrader: (25)

-Mark, so those spring rates intended are too limit roll to a desired level. can some of this also be accomplished with stiffer bars? also, how is the balance with such a setup? I have an '03 w/o a front LSD, would that affect your chocie of spring rates?

mayhem

iTrader: (9)

First we must say that those spring rates are intended for the lowered car. Like Mark explained, when the car is lowered through springs the front roll center point drops. How much it drops is why I asked for an autocad design of the Evo suspension in another thread . Anyway, the lower that roll center is the greater your roll moment is and requiring greater spring rates to deal with this. The lower you go the more quickly the front spring rates force will exceed the rear.

markdaddio

iTrader: (1)

The lack of a limited slip would not affect my choice for spring rates. If anything, you want to keep as much weight on the inner front tire as possible, meaning keeping a low dynamic center of gravity, which requires stiff springs. In addition, I might even consider running a little more rear spring and less rear bar w/o a limited slip. Just an idea that I might explore.
Mark

mayhem

iTrader: (9)

After some more thought on this something else came to mind. To preserve a flat ride frequency, when encountering bumps in road, a slightly higher rear spring rate would be desired. This typically would be something a street car manufacturer would strive for. To keep the flat landing and reduce the bounce you would want the rear to play catchup with the front so I higher rate spring would be required.