I am looking to replace my 2002 STI suspension/eibach springs with Cusco and the ratings of the springs are Spring rates- F: 7kgf/mm, R: 5kgf/mm, can anyone tell me if these are much harder as dont want to stiff a setup?

 

surely someone knows?????

 

Someone yesterday said here that standard 2002 STi was "2002-2003 STi "Pink" 215 190" or fronts 215 lb/in and rears 190 lb/in.

25.4mm is an inch and 2.20462lb is a kg. So 215 lb/in is 215/(25.4*2.20462) or 3.8 kg/mm and 190 lb/in is 190/(25.4*2.20462) or 3.4 kg/mm.

So, assuming yesterdays post was right and the numbers quoted were lb/in (almost certainly the case), then your 7 kg/mm fronts are 84% harder than standard and your 5 kg/mm rears are 47% harder than standard.

All you need to know now is how much stiffer the eibachs are than standard STi springs.

 

listen mate thanks a lot for that, will have a look at ravensblade website for eibach spring rates

 

And according to Fuzz here N/mm * 5.710143 = lb/in. So your kg/mm numbers are:

Fronts 7 kg/mm = 392 lb/in = 68.6 N/mm

and

Rears 5 kg/mm = 280 lb/in = 49.0 N/mm

Seeing as Graham 911 uses 60 N/mm fronts and 50 N/mm rears on his smooth tarmac hillclimb car (same post as above) I think your front springs will be way, way too hard and the rears a fair bit too hard.

 

oh right thats way too hard, but is what standard zero 2 cusco supsension is sold as.

How are you ever supposed to use that in normal road use?

Taken from imprezamods.com from ravensblade website
front and rear settings
Eibach 171 91-188

 

Hi there

I have an MY04 STI so similar weight and distribution

I have the AST 3 ways and the spring rates chosen by Powerstation are 65N/mm front and 50 N/mm rear - this is based on using the car for trackdays and sprints (in the future).

This is just great for trackdays and motorways but gives a very hard ride on normal B roads - if you do a lot of daily driving on B roads you need to drop by at least 10 to 15N/mm.

Hope this helps.

Dave

 

I was told if going with AST's to go for 40/30 setup for normal everyday road use

 

40/30 would be suited to a classic as a daily runner... On a bug/blobeye due to the extra weight it would be too soft. 50/40 would be better.

 

I'm no suspension guru, but working in imperial measures, 392's up front and 280's out the back are way too hard for any road driving. You'll be skipping and bouncing all over the road. Don't know how much you know about suspension but having spring rates too high on the road is not just a case of it being unconfortable - it's actually dangerous and will limit the way you can drive the car. That's from my experience of various cars in the past where I've fettled spring rates, damper settings, spring lengths, preload etc etc. Get the springs too hard for the road in an effort to keep it stiff on track, and the first time you brake hard the front end will literally skip along and double your braking distance. Really nasty.

 

I have 55F 45R and until you are breaking the speed limit they are too hard, once you are going quickly enough they are sublime though.