Does anyone know the stock spring rates of the 06 6MT Coupe? This has a sport suspension and I'm curious if the Eibach's I bought are actually stiffer or ???

The specs are not in the service manual.

Thanks!

 

Bump

 

Oem springs G35 coupes 2005/2006 with oem 19’s
Front:314 Rear:427


Eibach G35 Coupe progressive springs 1.1”/1” drop
Spring rates in LBS initial/final front 229/337 initial/final rear 274/463

Vs your oem springs
F +7% R +9% (looking at peak rates only)

Since they are progressive springs, they use a softer inital spring rate, your suspension much compress past these rates in order to get to the higher final rates.
F -27% R -36% (looking at softer inital rates)

Another spring choice with a simular drop
Tein 350Z S-tech 1.2"/1.1" drop on G coupe

Spring rates in lbs 386/402 (progressive front springs, linear rear springs)

Vs your oem springs
Stiffer then oem by F+23% R -6% (see note at very top)

 

Important to sum all the individual progressive rate segments to understand the total roll stiffness per degree of body roll.

Also because of angle and distance from wheel center line: 1 " of body roll may only compress a spring 1/4- 1/2".
So real roll stiffness is quite different from just spring stiffness alone

Most lux o sport vehicles have a REAL Front Stiffness of 150-200 pounds per body roll inch vs the 314 that many think applies.

229/337 initial/final might be 229 + 290 + 337 = 856 stiffness for 3" VS
314/314............................314 +314+ 314 = 942 stiffness for 3"

Many times Progressive have less or equal total stiffness than oem over the full range of typical movement [+-3" body roll].

 

Meaning: The amount of suspension travel to bind coils into sudden rate change is still their just in a different range since motion rate back to the springs "thinking" wasn't taking place. And that with this factored in total roll stiffness in the end isn't likely to be any higher then oem.


[QUOTE=Jason@Performance]Every suspension that we have installed here I have test drivin the car... So I can give my feed back on almost all of them... But... I will do my personal car which I beat the heck out of every day...



Mod: Eibach 350z Pro-Kit

Pros: Great appearance, Sits about 1.2" lower then my car before. Nice smooth ride on surface streets and freeways...

Cons: Springs very soft so in heavy cornering especially in track conditions there is alot of body roll... so much that it is hard to predict when the car is actually going to bite into the corner...

Recomendation: I would recomend this spring for someone who wants a lower stance and smoother ride. But does not plan on seriously tracking the car to the limits./]

 

Progressives can be tricky for the newbee or inexperienced with the specific vehicle in wet or snowy conditions..............most expect linearity.

 

A lot of the aftermarket springs out there are not the actual advertised spriong rates as the manufactuer claims. Check out www.swiftsprings.com By far the best springs that I have seen to date. Most accurate spring rates and they make replacement springs for most coilovers.