I posted this about a month ago in this section. Thread title was pretty much the same as yours as well. I would give them to you now, but don't have them on this computer.

 

I posted this about a month ago in this section. Thread title was pretty much the same as yours as well. I would give them to you now, but don't have them on this computer.

Is this what you are looking for TiC?
Front spring rate: 38 N/mm ~ 217#
Rear spring rate: 34 N/mm ~ 194#

 

Where did you guys find the numbers? Link for reference from Subaru or some one?

 

From subaru.

Thanks S'poreSTI.

 

Cool, I'll use these until someone can prove they're wrong lol. Thanks TIC and Spore

 

Crazy that the spring rates would be nearly identical to earlier STI's even though the motion ratios are different. To make an old STI feel like the new one, replace the rear springs and dampers with parts from a WRX. That's close to what Subaru's new setup is when measured at the wheels.

 

To make an old STI feel like the new one, replace the rear springs and dampers with parts from a WRX.

How about to make a new one feel like an old one? God I miss my 05!

 

Hope these are right, I did my calculation of spring rates and increases in the Spring Review Thread to fill in the blanks :lol:

 

why do you need to divide twice?

 

Wheel rate = spring rate * motion ratio ^ 2.

So if you have a 100lb/in spring with a motion ratio of 0.5, your wheel rate is only 25lb/in.

This is because for every inch of wheel movement, the spring only compresses HALF an inch. Additionally, the wheel has leverage over that spring, so it only needs to exert 50lbs for every 100lbs of resistance at the spring. Thus, you multiply the spring rate by the motion ratio twice to get the wheel rate.


Edit: Can anyone confirm that the motion ratio in the rear is 0.8? I don't own a GR. I thought Turn-In Concepts measured this, but I searched and couldn't find it. I hope I'm not completely making that number up, but my mind has done stranger things before.

 

Bump for confirmation of the motion ratio in the rear. Anyone? Just measure the length of the entire rear suspension arm, then the distance from one mounting point to the damper & spring mounting point. That's all I need to know.

 

It's .8 in the rear per our measurements.

 

so then that means..assuming a similar weight distribution from the GD to the GR, A typical coilover springrate of 500/400 (9kg/7kg) (ie RCE T2), for the GR would need to be 500/625 (9kg/11kg) in order to behave similarly. true?
why don't GR coilovers come like this then? and would revalving be necessary to support the rear spring rate...

 

a stiffer spring in the rear will get the car to rotate faster but from my experience with a similar rear suspension design on the '05+ LGT with 8k/8k Cusco Zero2, the rear end will 'load' over stutter bumps and launch vs. absorbing the imperfections.