Spring rate choice and Front / Rear distribution

[Isofouet]

Hello,

I'm looking for springs to fit the koni yellow I ordered.
(Please no debate on this choice vs coilover, for this budget, I think it's the best solution)

I want a setup for road driving, and particularly bumpy roads...
And I wonder what to choose...

Reading this topic, I think something like 5/4 should be OK
I will also install Whiteline sway bars to counter the rolling

But, when I look the characteristics of some specific kits for the S15, I'm a bit lost...
Some examples :

Tein S tech Medium springs : F:3.5 R:4.1
Tein S tech Soft springs : F:2.6 R:3.1
Nismo Stune Shocks : F:4.5 R:5.5
But : Tein Street Advance Damper : F:5.0k R:4.0k
etc

So, why for some kits the rear springs have a higher rate ?
I believe it will give an oversteering behaviour of the car, won't it ?
And all the coilover kits have a higher rate on front...


In conclusion, I don't know which spring to choose...
I don't want a very firm ride... In fact, with 18" wheel, I already find the stock suspension quite hard...
By the way, do you know the stock rates ? I can't find reliable figures ?

Thank you, and happy new year !

 

[Auss15]

I would go 6 F and 4 R for a balanced feel without to much harshness on the road. I can only think stiffer then front rears for drift cars. Everyone I know has stiffer fronts to rear.

Can you get Eibach Springs over there ?

 

[pegliobaglio]

just nicked this off of the sxoc coilover group buy,gives a rough idea of spring rate uses

Our complete range of normal coilovers is:

Apex 4/3kg.mm Limo - for nasty roads, will cope with occasional track use
Apex 5/4kg.mm Comfy - for normal roads retaining a high degree if usability whilst being more than happy on track
Apex 6/5kg.mm - more serious fast road and track set up
Apex 8/6kg.mm - we are staring to get into dedicated drift car or damm serious fast road and track set up
Apex 10/8kg.mm - dedicated track set up on road tyres or road legal rack tyres
Apex 12/10kg.mm - dedicated track set up on slicks or track tyres
Apex 14/12kg.mm - another option for slick shods track cars or track tyres with good aero package
Apex 16/14kg.mm - if youre running serious aero on slicks then you need to be looking at these

The more serious above set ups are vaugue recommendations only, ultimate spring rates depends on a huge range of factors so its very much a test and try situation but that gives you some ideas to begin with.

 

[TomK]

I dont know why all the aftermarket coilovers do the front stiffer?

Stock: F 2.2 R 2.4
Nismo Factory Option: F 3.0 R 3.2
Nismo S-Tune: F 4.5 R 5.0

I would thought if anybody would get it right it would have been the R&D at Nissan and Nismo.

On a side note the springs from my Nismo Option suspension will be up for sale at the end of the month.

 

[Max]

My HKS Hipermax Performers are 6kg Front, 4kg Rear (and they should be just as comfy as S-tunes) for a fast road setup. Tbh I hope I won't be making it uncomfortable when I fit them along with Nismo and Energy bushes everywhere.

 

[S15_SAM]

Bushes don't make it much more bumpy, but the vibrational noise they create can be abit "uncomfortable"

 

[pegliobaglio]

Hmm depends what suspension you are running as mine became a lot harsher when I changed all the arms and arb links etc on mine. Saving up for a set of hsd's or cs2's now to try get a better ride

 

[TomK]

There is a couple of threads about that discuss putting poly bushes in the uprights at the rear can cause issues and you would be better of there with rubber. OEM type bushes or sherical bearings, other than that it 'shouldnt' affect the ride other than increased vibration being transmitted.

 

[TomK]

On a side note, I went for the limo apex coilovers to cope with the awful roads here.

 

[Isofouet]

I dont know why all the aftermarket coilovers do the front stiffer?

Stock: F 2.2 R 2.4
Nismo Factory Option: F 3.0 R 3.2
Nismo S-Tune: F 4.5 R 5.0

I would thought if anybody would get it right it would have been the R&D at Nissan and Nismo.

On a side note the springs from my Nismo Option suspension will be up for sale at the end of the month.

That's really the point that make me doubt...
Considering my setup will be relatively close to stock (with koni yellows), I wonder if these type of springs aren't a good solution...
I don't plan to do some track days, and with sway bars, I think the roll will be quite contained


More over, it seems differences can be found between S14 and S15 springs for severals makes...
Sometimes the S14 springs are stiffer.. I don't know really why : the S14 is slightly heavier, but the difference is not so huge ?

Thank you for all your answers !

 

[TomK]

I thought the s14 ran front 2 and rear 2.2

 

[Auss15]

The S14 suspension is slightly softer then the S15