Shaping up a new-to-me 07 GT3
06-17-2014, 06:41 AM
#152
This thread is about the build of my car. We got side tracked a bit by chatting about suspension setup and then DSC. In regard to PSM, I was only pointing out one car that was used for DSC development ran on track with PSM "ON" for the purpose of illustrating the lap times that are possible even with the nanny device on. 
Sorry for the confusion. I will do my best to stay on topic and answer questions.
Sorry for the confusion. I will do my best to stay on topic and answer questions.
Its good to have an interesting thread that doesn't include GT3/RS prices/values or GM product
06-17-2014, 01:44 PM
#153
Drifting
The .2 front spring is part # is 997 343 531 94. They are very pricey from the dealer and only marginally stiffer than .1 springs(see photo for actual in-lb rating). I used them because there was a pair in the shop's spring inventory that wasn't being used, which I eventually returned. If I were to buy front springs to match the stock .1 rears I'd go with something like 350 or 400. You'll need 9 inch tall springs at those rates. If you have access to metric size 60mm ID springs it'll be a direct swap. Metric size springs are harder to get here in the US so we convert to 2.25 inch ID which requires changing the spring hat and perch to make up of the difference of a measly 0.112 inch diameter.
Would Eibach RF200070 work ? That is a 200mm length spring vs 228(9")
Thank you!
06-17-2014, 04:45 PM
#154
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I personally think 200mm(7.9") length is shorter than ideal for 350-400 lb springs but there should be enough threads on the stock front shock body to make it work. I would definitely prefer a longer(9") spring to be closer to the middle of the threaded body for this stiffness range. Your ride height will also have an impact on this matter. And you have to factor in the amount of spring sag(compression) by the weight of the car when using front springs that are less than say 500 lbs. The stiffer the springs the less sag it will have by the weight of the car.
If you are inexperienced with doing this kind of measurement/calculation, I would suggest for you get help from a local professional. Not worth it to mess you your shocks or car.
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06-17-2014, 05:39 PM
#155
The Rebel
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Just to clarify something, .1 cars do NOT have PSM they have PASM. My guess is that, this is probably the reason why .1 cars only have 2-axis accelerometers and not the 3-axis ones needed by the DSC.
What would you recommend for a track (smooth track) only .1 RS as far as spring rates if using stock PASM dampers and the DSC?
What would you recommend for a track (smooth track) only .1 RS as far as spring rates if using stock PASM dampers and the DSC?
06-17-2014, 06:02 PM
#156
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Just to clarify something, .1 cars do NOT have PSM they have PASM. My guess is that, this is probably the reason why .1 cars only have 2-axis accelerometers and not the 3-axis ones needed by the DSC.
What would you recommend for a track (smooth track) only .1 RS as far as spring rates if using stock PASM dampers and the DSC?
What would you recommend for a track (smooth track) only .1 RS as far as spring rates if using stock PASM dampers and the DSC?
In regard to springs, you could just put 400's in the front and call it a day since rear spring change require some type of rear mount kit or adaptors. If you don't mind fiddling with the rear then 500/700 or 550/750, or 600/800 are good choices. I would be reluctant to run the latter two choices if your stock shocks have been subjected to a lot of usage. I have seen early .1 rear shocks puke oil around the seals when they have a lot of track miles on them even with no mods whatsoever. There was a factory updated part number for the .1 shocks for 2008 production year, perhaps they have better seals. Bottom line, worn seals + stiffer springs = no bueno. This applies to any shock, PASM or not. On the other hand, one could argue that a stiffer spring will result in less/slower movement from a shock, therefore requiring less work from a shock compared to one that's undersprung. Very confusing I know!
Last edited by Tom@TPC Racing; 06-17-2014 at 09:59 PM. Reason: More details on last paragraph
06-17-2014, 09:06 PM
#157
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Rear upright bushing
The next suspension part I "Might" try to make is a spherical bearing insert to replace the rubber on our rear uprights. All 997 street cars have the same rear uprights with rubber bushing(except for 4.0 and GT2RS).
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
06-17-2014, 10:51 PM
#158
The Rebel
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Correct on .1 GT3 does not have PSM.
In regard to springs, you could just put 400's in the front and call it a day since rear spring change require some type of rear mount kit or adaptors. If you don't mind fiddling with the rear then 500/700 or 550/750, or 600/800 are good choices. I would be reluctant to run the latter two choices if your stock shocks have been subjected to a lot of usage. I have seen early .1 rear shocks puke oil around the seals when they have a lot of track miles on them even with no mods whatsoever. There was a factory updated part number for the .1 shocks for 2008 production year, perhaps they have better seals. Bottom line, worn seals + stiffer springs = no bueno. This applies to any shock, PASM or not. On the other hand, one could argue that a stiffer spring will result in less/slower movement from a shock, therefore requiring less work from a shock compared to one that's undersprung. Very confusing I know!
In regard to springs, you could just put 400's in the front and call it a day since rear spring change require some type of rear mount kit or adaptors. If you don't mind fiddling with the rear then 500/700 or 550/750, or 600/800 are good choices. I would be reluctant to run the latter two choices if your stock shocks have been subjected to a lot of usage. I have seen early .1 rear shocks puke oil around the seals when they have a lot of track miles on them even with no mods whatsoever. There was a factory updated part number for the .1 shocks for 2008 production year, perhaps they have better seals. Bottom line, worn seals + stiffer springs = no bueno. This applies to any shock, PASM or not. On the other hand, one could argue that a stiffer spring will result in less/slower movement from a shock, therefore requiring less work from a shock compared to one that's undersprung. Very confusing I know!
The next suspension part I "Might" try to make is a spherical bearing insert to replace the rubber on our rear uprights. All 997 street cars have the same rear uprights with rubber bushing(except for 4.0 and GT2RS).
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
06-18-2014, 04:25 AM
#159
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The next suspension part I "Might" try to make is a spherical bearing insert to replace the rubber on our rear uprights. All 997 street cars have the same rear uprights with rubber bushing(except for 4.0 and GT2RS).
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
I made something like
but with a big nut rather than a circlip
with the top of the schock mounted with uniball and the car without wheels, I can move it a little (no play but "free")
06-18-2014, 09:47 AM
#160
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The next suspension part I "Might" try to make is a spherical bearing insert to replace the rubber on our rear uprights. All 997 street cars have the same rear uprights with rubber bushing(except for 4.0 and GT2RS).
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
The rubber bushing that mounts to the bottom of the rear shock seem to move a bit when used with all stock suspension. The reason I said "Might" is because I think the upper mount kit I installed has stabilized the shock enough so the juice may not be worth the squeeze. Plus I have to sacrifice an upright to make the first one. Anyone want to send me an upright to tinker with? Its for a greater good.
06-18-2014, 10:23 AM
#161
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The metal c-clip and a stopper shoulder on the insert is the way to go. That's the method I would use if I were to make them.
Thanks.
06-18-2014, 10:26 AM
#162
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06-18-2014, 11:47 AM
#163
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bearing cost a few euros, and all aroud is home built ... but it seem you have a lathe near you
Outside, I have a "big" nut with "angular contact" on the hub, rather than a circlip, because the inside housing of the hub is not flate all around
As I made this part without unfitting the hub, I couldn't "reflat" all around to make insert contact all around ... not sure I am very clear with explainations
I have Inventor drawing if you want ...
06-18-2014, 12:11 PM
#164
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It's metal spherical bearing inside a 2017 tube, hold in place by a threated insert
bearing cost a few euros, and all aroud is home built ... but it seem you have a lathe near you
Outside, I have a "big" nut with "angular contact" on the hub, rather than a circlip, because the inside housing of the hub is not flate all around
As I made this part without unfitting the hub, I couldn't "reflat" all around to make insert contact all around ... not sure I am very clear with explainations
I have Inventor drawing if you want ...
bearing cost a few euros, and all aroud is home built ... but it seem you have a lathe near you
Outside, I have a "big" nut with "angular contact" on the hub, rather than a circlip, because the inside housing of the hub is not flate all around
As I made this part without unfitting the hub, I couldn't "reflat" all around to make insert contact all around ... not sure I am very clear with explainations
I have Inventor drawing if you want ...
06-18-2014, 12:21 PM
#165
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GT3 twins!
Off topic for a moment here. I think of the other GT3 as a twin to mine. TPC has been servicing this car for years. It changed ownership from one great customer to another. Between the two owners I had the opportunity to buy it before I bought mine but I didn't have enough mula, as it is a nicer car than mine. Glad to see it come back home!