robzter

Hello im about to order a set of BC coilovers and can get them with my desired spring rate. BC recomended 4kg in the rear but isnt that much compared to OEM thats like 3? will the car still be streetable?

need help ASAP since im making the order this week

ultimatejay

iTrader: (1)

Here in the states we deal in lbs. I have no idea how much 4kg is without spending time converting it. I/we will need the kind of car and also need the weight of the car with you in it and the type of suspension/ rearend and if you plan on only using it as a street/strip car or stickly drag.

robzter

The car weighs about 1200kg with me i guess (lighter seats, interior, no powersteering, no ac atm) The car itself is going to be used on the street alot and also racing on the streets. so want it to get lots of grip even when its not so sticky. probably forgot to mention its an FD with kaaz diff in the rear and nylon/steel bushings, OS giken twin plate clutch. singleturbo with about 550hp in the motor

i found this spring rate converter on evolutionm.net

kg/mm to lbs/in
-----------------------------
16 = 896
15 = 840
14 = 784
13 = 728
12 = 672
11 = 616
10 = 560
9.0 = 504
8.5 = 476
8.0 = 448
7.5 = 420
7.0 = 392
6.5 = 364
6.0 = 336
5.5 = 308
5.0 = 280
4.5 = 252
4.0 = 224
3.0 = 168
2.0 = 112

beefcake

i dont know about street stuff but for irs drags the stiffer the better, get rid of squat , but it may be counter productive on the non sticky street . IMOP
Thanks for the chart, i was looking for a lbs converter too

blitzboy

Now this could be where you are going wrong and not hitting 9s, mine is nice soft on my HKS drags and plenty of squat with not much rebound.

My rear spring rate is about 4kg at the back

http://www.youtube.com/watch?v=8KA4F6OMfHo

ultimatejay

iTrader: (1)

^ I agree. Look at Timemachines and Enzo' s car on launch. There is alot of squat on those cars. Stock springs believe it or not are pretty close to where you want to be for a street/strip car. Most full out drag cars will use a lower spring rate depending on weight of car and suspension setup. I would just recommend using the stock springs for your application.

beefcake

Ive had two chassis guys at my track tell me to run stiff springs with irs , having your rear end bouncing up and down does seem a sure way to unsettle it .
I know it goes against what companies like hks do and others have done , but to me it makes sense .
With traditional rear ends it makes sense to soften it a little , Irs behaves differently to live axle rear ends.
Id love to have more of a discussion on this with some other chassis professionals for sure .

Thanks for the ideas though guys , i do feed on it

Also does 1.32 and many more 1.30s 60ft say im going the wrong way , so far its ok, its just i cant drive straight and i cant shift gears, and i only have 450~490 hp at the wheels ?

Blitz, i fn love the way your car squats and stays squatted , its poetry