I was using Motons in my 996 with 2.25" inner diameter springs (57mm). I think they were smaller than the stock ones, but I can't verify (I sold my stock suspension).

I would prefer not to remove a strut to take measurements.

As far as I remember, I think the stock GT3/GT2 uses 60mm diameter springs, but I would like someone to confirm this.

I'm looking at changing the spring rates while keeping the smart/dual setting PASM shocks.

 

i will try and measure later
would love to be kept up with what you are thinking as i would like to do this as well
i.e. put firmer springs front and rear and keep pasm working

do you think that the shocks will have to be revalved for this to work

 

I'm planning on rear spring rates close to stock, with linear rather than progressive springs, no revalving necessary on that axle.

The front might not need it either, as I would be increasing stiffness by less than 150% (assuming the stock spring rates are on the mid 200#)

There are more spring choices on the 2.25" (57mm) and 2.50" (63mm) types, but I think the stock ones are somewhere in the middle, so changing the springs to different diameter will require new spring perches, top, bushings, etc, I prefer not to change that.

 

the rear spring appears to be fully compressed in the progressive section so my guess is that it is acting like a liner spring anyway

 

- some info on the springs

- went out to the car, removed the wheels and did my best with a tape meassure

Front spring
- the linear ones
- the external meassurement appears to be about 3.25 inches
- the internal meassurement appears to be 2.5 inches
- the height of the spring with the wheel off is around 8.5 inches
- the spring has a part number and it says H&R R/K on it
- part number 996.343.531.95

The rear
- the progressive ones
- the progress part is at the top and even with the wheel off there are about 4 rings that are basically touching each other
- the external width at the top is almost 4 inches
- the spring itself is about 1/2 thick so the internal meassurement at the top would be 3"

- the bottom part of the spring (the linear part)
- at the very bottom, the external width is just less than 3.5 inches so the internal meassurement would be very close to 2.5 inches

- the length of the spring with the wheel off was about an inch longer than the front so lets say 9.5inches


hope that helps


paul

 

Paul,

You're some serious help. I have to do a brake job later today (switching to PCCB), and I will check on the suspension.

Thanks a lot for your time and the detailed explanation. This is the type of information that helps this forum to be so valuable.

 

Rad,

I was thinking the same thing, regarding re-springing the Gt3, and checked the front spring part #'s yesterday. 996.343.531.95. I only checked the fronts.

I think that the 997 GT3 spring rates are:
F: 45nm/256.5 ft/lbs R: 105nm/598.5ft/lbs.

I don't know what the spring diameters are, but Greg F. is looking at this for me. We are thinking along the lines of 350/600 front/rear. Your Idea of removing the progressive rears is a good one. Please keep me posted. I'm going down the same road as I did with the 996.

Robin

 

I'll just wait on the sidelines and let you guys handle the development.

Love threads like this as opposed to all those RMS issues that were plaguing the forum.

 

Ok, I used a caliper to measure the inner spring diameter. They're 60mm.

I double checked with the stock spring perches.

 

http://shop.fvd.de/de/en/Porsche-0/-...GT3-T%DCV.html
Anyone seen or heard of this system ? It's supposed to be a specific fitment for the 997 GT3/GT2 and is PASM compatible. It's not on the Bilstein site, but listed on the FVD page. I have asked FVD to provide detailed specifications. I'll publish them as soon as I get them. Which brings the question. Who is the PASM OEM supplier to Porsche ?

Robin

 

I enjoy this topic as well, Paul and I have discussed set ups and desire to play with spring rates. As to the above, where did you get the data on the OEM spring rates. I am going to respring my car this winter, and if I cannot get reliable data on what I am starting with, I was just going to take the OEM springs off and have them tested first. So is that off a speck sheet or educated guess???

 

Frank,
I got the numbers from another thread here :https://rennlist.com/forums/showthre...t=spring+rates
The numbers correspond with those published in Excellence. I am also having mine checked this winter, if I can't get a confirmation from a Porsche source.
I'm a firm believer in more spring on the GT3, but I wouldn't want to overwhelm the dampers. My 996 GT3 had 600/800 cup car springs, with Motons, and several other suspension mods.

Robin

 

I think AWE advertised this Bilstein set-up a few weeks ago. Might not be on the official Bilstein site though. No idea about it at all and I don't know anyone who installed it. It'll be nice if someone takes the plunge and gives us his/her impressions.

 

The front 997 GT3 spring is the same part # as the 996 GT3
996 343 531 95

Now the rears are a different part # so I can't help on what their measurements are.

 

I emailed FVD, who also advertised this setup, and asked for deailed specifications. The answer I got was essentially " Bilstein won't give those out, they don't want the competitors to get it "

Well, I geuss they don't want to sell too many of them if they think people will buy suspension mods for a GT2 or GT3 without specifics, like spring rates.

Robin