997 Spring Rate roundup!!
 

Hi all,


Fairly new to 997 ownership (2009 Carrera), I drove it home the week before the snow and so spent the winter lurking on the forums. As I've upgraded the suspension on various other cars before I collated all the spring rate data I could find for the 997's.


My disclaimer is this rate data is primarily surveyed off the forums, it's just presented here in one place.


The eibach rates I found over on 6Speed were quoted as,
F
19/34 nm
168/300 in/lbs

R
52 /90 nm
460/796 in/lbs


Which does not compute as the conversion rates are wrong. I've used the n/mm values.


Of note both the eibach and Pss9 progressive rates start lower than stock - this is not necessarily true when installed on the car as static sag will 'take up' some of this lower rate travel. Given that most people who install these springs saw they find ride to me more compliant than stock over smaller bumps this might reflect the initial lower rate. Of course this will quickly rise as the suspension moves.


The table attached gives the rates plus a comparison % to the stock C2 Carrera rates so you can see how much stiffer the springs are than stock. Plus a front/rear comparison that shows how much stiffer the rears are to the front.


You care about this as stiffer rear/softer front will tend to dial out understeer, so you would expect that the KW V3's at over 400% stiffer at the rear would give less understeer than even a GT3 stock setup.


Anyway - enjoy!!

Hey that's awesome! Keep it updated if you can with more sway bar numbers.

I am a retired mechanical engineer and had a lot of experience with spring rates including ski safety bindings. Please remember that the Eibach Sport are progressive spring rate and I have used them from 1983 URQUATTRO to my 997.1. IMO-still the best!

Another retired mechanical engineer an I am a big fan of the TectArt by Eibach springs . I have them with Bilstein B6 struts and Eibach swaybars all coupled with PS4S tires. Best ride ever! By basalt black 997.2 is way better than with the stock setup. My opinion.

Why two lines for Eibach and H/R?

Maybe they are progressive spring rates? Min/Max?

I think it is because they are progressive rate springs.

yes min/max values what I don't know is how much travel is left at the lower rate one the car is on the ground and the lower rate coils compress.

I have Eibachs on my car and my immediate impression is they are stiffer than the stock springs.

BTW Slight differences in the Eibach Pro Springs, depending on your model, got these numbers directly from Eibach today:

4 and 4S, part number EIB 7222-140.

Front springs = 115 lbs/in - 228 lbs/in

Rear springs = 291 lbs/in - 514 lbs/in

C4s have extra weight in front, thanks to the front gearbox.

Thanks for the original post / chart! Great information to use when thinking about setup.

I am running the DSC box with PASM B4 OEM replacement shocks and stock springs. On Track, noticing a big bounce when i hit an s curve and shifting weight from left to right and right to left, intermediate skill level.

Tom at DSC says the box is at full stiff on the shocks when at 1G or more, but i think i must be less than a G when the bounce is happening. Looking at the Eibachs to help.

Now someone needs to dyno the shocks so we know which springs match.

Delete me.... was responding to another thread...