997 GT3.mk1 PASM re-valve begins
#121
Drifting
Thread Starter
R888 is better on the track - if only because it has no tread blocks to move around under load. I also found it a good tire from the 1st corner out of pit lane. The tire has a very stiff sidewall so it needs less camber - do not over camber this tire. The R888s in 18s have a 255 which makes for a perfect front tire - ie maximum width. The R888s need to be run at lower temps than originally stated by the manufacturer to have good grip - ie around 31/33f, can't remember the rear temp I liked. One word or caution on this tire, when the rears start to go, they can and do lose grip levels extremely quickly - as in, you are doing 1.2G corners and then all of a sudden your rear comes around at .6G - you have to keep this at the back of your mind so that you don't cause yourself a car wreck - if the tire is going, it will go very quickly.
Last edited by 997gt3north; 09-25-2011 at 05:13 PM.
#122
Drifting
Thread Starter
Another mini update
When I was driving to Mosport for the car's first shakedown, I was noting on the highway that I thought the front's were slightly under dampened in Normal mode but basically spot on in Firm mode - it was Firm mode I used on track that day.
Well, guess what, the shop mistakenly re-used my front 450# valved shocks with the 618# springs instead of putting on the shocks that were re-valved for 600#s with the 618# springs. Obviously I plan on changing this shortly.
Why I thought I would mention this is that it is a little case study that may be useful to others. And that is, the Firm setting basically increased the damping rate enough that it perfectly (in my opinion) dampened a spring that was 168#s higher than the rate that the shocks were valved for.
What this likely means is that a stock valved car can most likely change out the stock springs to a 375/750 setup and just run the car in firm mode and the valving should be pretty close to optimal. I personally would go the extra mile and re-valve them and would recommend a 700/900 setup but it is useful data from my shop's mistake.
The other possibility is to use this data to design your own PASM setup / spring rate given your local tracks that you run. Let's say for example you run bumpy Sebring and smooth other. Given such, send out your shocks and have them valved for Front = 600#s and rear =800#s. Install 700/900 spring. For Sebring bumpy track, run the car in Normal Soft mode and then for other track, run the car in Firm mode. The spring rates 700/900 give you the better spring rates than stock, and then PASM allows you to run bumpy or smooth tracks - very much like Porsche intended - this is what I will be doing.
When I was driving to Mosport for the car's first shakedown, I was noting on the highway that I thought the front's were slightly under dampened in Normal mode but basically spot on in Firm mode - it was Firm mode I used on track that day.
Well, guess what, the shop mistakenly re-used my front 450# valved shocks with the 618# springs instead of putting on the shocks that were re-valved for 600#s with the 618# springs. Obviously I plan on changing this shortly.
Why I thought I would mention this is that it is a little case study that may be useful to others. And that is, the Firm setting basically increased the damping rate enough that it perfectly (in my opinion) dampened a spring that was 168#s higher than the rate that the shocks were valved for.
What this likely means is that a stock valved car can most likely change out the stock springs to a 375/750 setup and just run the car in firm mode and the valving should be pretty close to optimal. I personally would go the extra mile and re-valve them and would recommend a 700/900 setup but it is useful data from my shop's mistake.
The other possibility is to use this data to design your own PASM setup / spring rate given your local tracks that you run. Let's say for example you run bumpy Sebring and smooth other. Given such, send out your shocks and have them valved for Front = 600#s and rear =800#s. Install 700/900 spring. For Sebring bumpy track, run the car in Normal Soft mode and then for other track, run the car in Firm mode. The spring rates 700/900 give you the better spring rates than stock, and then PASM allows you to run bumpy or smooth tracks - very much like Porsche intended - this is what I will be doing.
#123
Rennlist Member
What this likely means is that a stock valved car can most likely change out the stock springs to a 375/750 setup and just run the car in firm mode and the valving should be pretty close to optimal. I personally would go the extra mile and re-valve them and would recommend a 700/900 setup but it is useful data from my shop's mistake.
I should have everything installed and ready for a shakedown on Oct. 22nd, after I get back from Oktoberfest with the M3.
#124
Drifting
Thread Starter
A few pictures to finish off this thread.
Somewhere between 2007 and 2008 model years, the rear shock bodies went from being fully threaded to only have the lower third of the shock threaded. For anyone that may go through a re-valve, if you have a fully threaded shock, you can probably use 5-6" springs with helpers - if you have the partially threaded shock body, 7" for the rear with tender, is likely a better fit - this all depends on ride height.
The picture you see below is from a rear shock with only the lower third being threaded - it has a 898# spring with a 168# tender (0.9 inch block height / 60mm free length) and the car has been lower approximately 10mm.
If you look closely, you can see that when you look through the main blue spring, there is no threaded portion.
<-------------- you can see how this is different than in my picture poster that has a fully threaded shock body (if you look closely)
Somewhere between 2007 and 2008 model years, the rear shock bodies went from being fully threaded to only have the lower third of the shock threaded. For anyone that may go through a re-valve, if you have a fully threaded shock, you can probably use 5-6" springs with helpers - if you have the partially threaded shock body, 7" for the rear with tender, is likely a better fit - this all depends on ride height.
The picture you see below is from a rear shock with only the lower third being threaded - it has a 898# spring with a 168# tender (0.9 inch block height / 60mm free length) and the car has been lower approximately 10mm.
If you look closely, you can see that when you look through the main blue spring, there is no threaded portion.
<-------------- you can see how this is different than in my picture poster that has a fully threaded shock body (if you look closely)
Last edited by 997gt3north; 10-13-2011 at 07:40 PM.
#125
Drifting
Thread Starter
This should be the last 2 pictures for this thread.
Below is two different pictures of my front setup.
The spring is a 7" Swift 616# spring
The Tender is a Swift 45# 70mm free length with 0.94 inch Block Height
The car has been lowered about 10mm - to be exact, the ground to fender on the front axle is 25.5 inches - the rear is 25.6 inches.
The uncompressed tender spring shows how much a 616# front spring has to be 'tendered' at full droop.
Below is two different pictures of my front setup.
The spring is a 7" Swift 616# spring
The Tender is a Swift 45# 70mm free length with 0.94 inch Block Height
The car has been lowered about 10mm - to be exact, the ground to fender on the front axle is 25.5 inches - the rear is 25.6 inches.
The uncompressed tender spring shows how much a 616# front spring has to be 'tendered' at full droop.
#127
Rennlist Member
It's all the same. Remove rear shelf carpeting. You'll find the base of the half-cage mounted on top of rear shock tops. The screws from the shock absorbers come through the tub and through the drill holes in the base of the cage, secured by hex nuts on the cabin side. Remove nuts as you would normally and the shock can be removed from underneath.
#130
Drifting
Bumping this thread up.I have gone ahead and taken OP advise, per this thread and ordered swift spring set: Z60-203-060 Z60-203-060 I pinged Tom at TPC informing him that I purchased Swift springs to try reduce the amount of nose dive in the front of the car, if anything can be done via DSC – Tom immediately replied back asking a few questions regarding my DSC unit and swaybar. Next thing I know boom I had a DSC file to upload to my unit.Very cool that you can do this type of stuff with DSC. Obviously the DSC was not available with the OP started this thread, therefore lets call this round 2.As for the rear springs, anyone know what are the best options available today? If not I can make something however I rather just get something off the shelf. I see that Tarret’s product sometimes hits the swift spring. Has this been addressed and a revised product design ? Or did I misunderstand. Goal : Less nose dive, faster turn in at front and i dislike understeer.
#131
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Bumping this thread up.I have gone ahead and taken OP advise, per this thread and ordered swift spring set: Z60-203-060 Z60-203-060 I pinged Tom at TPC informing him that I purchased Swift springs to try reduce the amount of nose dive in the front of the car, if anything can be done via DSC – Tom immediately replied back asking a few questions regarding my DSC unit and swaybar. Next thing I know boom I had a DSC file to upload to my unit.Very cool that you can do this type of stuff with DSC. Obviously the DSC was not available with the OP started this thread, therefore lets call this round 2.
We do have a kit to convert the rear top mounts to monoball with motorsport style hats that makes universal-shaped racing spring compatible on OEM PASM rear shocks.
Link here- http://www.tpcracing.com/997-gt2-rear-top-kit.html
Since you increased the front spring rates to reduce dive, you'll need 700-800 lbs springs in the rear to balance the car. The stiffer rear springs will help transfer the weight to the front.
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TPC Racing stats:
2023 Porsche Sprint Challenge 992 Cup Am Champion
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2022 Porsche Sprint Challenge 992 Cup & 991 Cup Champion
2020 IMSA GT3 Cup Challenge 2nd Championship
2018 IMSA GT3 Cup Challenge 2nd Championship
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PCA National Instructor
TPC Racing stats:
2023 Porsche Sprint Challenge 992 Cup Am Champion
2023 Porsche Sprint Challenge GT4 Pro-Am Team Champion
2022 Porsche Sprint Challenge 992 Cup & 991 Cup Champion
2020 IMSA GT3 Cup Challenge 2nd Championship
2018 IMSA GT3 Cup Challenge 2nd Championship
2016 IMSA GT3 Cup Challenge Champion
2013 IMSA GT3 Cup Challenge Champion
2006 Rolex-24 @ Daytona GT Champion
2004 Grand-Am SGS Class Champion
#132
Drifting
^ Thank you Tom. I'll definitely look into your kit after some real seat time on the car.
Finally got around installing the front springs, yesterday. It took me about ~6 hours that said, 4 hours was mostly cleaning front fender well area. Driving around it feels much better then oem. I will write a detail write up after a few weeks of driving. Thus far, massive thumbs up.
Thank you to the OP.
Finally got around installing the front springs, yesterday. It took me about ~6 hours that said, 4 hours was mostly cleaning front fender well area. Driving around it feels much better then oem. I will write a detail write up after a few weeks of driving. Thus far, massive thumbs up.
Thank you to the OP.
#133
Rennlist Member
I have DSC on 16RS.
Had to soften the std file to create the nose going down and rear going down like OEM with new file.
it helped with lean.
Next i am for stiffer springs (emulating new .2RS) I assume I can soften the sway bars more then they are now.
We’ll see what that does. I’ve a cable under my passenger seat to the DSC to make quick changes :-)
Had to soften the std file to create the nose going down and rear going down like OEM with new file.
it helped with lean.
Next i am for stiffer springs (emulating new .2RS) I assume I can soften the sway bars more then they are now.
We’ll see what that does. I’ve a cable under my passenger seat to the DSC to make quick changes :-)
#134
Drifting
I have DSC on 16RS.
Had to soften the std file to create the nose going down and rear going down like OEM with new file.
it helped with lean.
Next i am for stiffer springs (emulating new .2RS) I assume I can soften the sway bars more then they are now.
We’ll see what that does. I’ve a cable under my passenger seat to the DSC to make quick changes :-)
Had to soften the std file to create the nose going down and rear going down like OEM with new file.
it helped with lean.
Next i am for stiffer springs (emulating new .2RS) I assume I can soften the sway bars more then they are now.
We’ll see what that does. I’ve a cable under my passenger seat to the DSC to make quick changes :-)
Do you happen to know what 16RS spring rate is up front and weight on each corner ? I'm curious.