Stock Spring Rate Change? What would you recommend?
07-15-2013, 01:15 AM
#1
Rennlist Member
Thread Starter
Stock Spring Rate Change? What would you recommend?
2010 GT3 (non-RS), 11,000 mi; the last half all track. It has GMG Tarmac series suspension components, magnetorheostatic engine mounts and bone-stock shocks. This is essentially a track-only car, trailered to events. Should I increase the spring rates, and if so, should I keep the stock shocks, exchange springs for slightly higher spring rate and leave the rest alone, or change springs and re-valve the shocks OR replace the shocks? I am not the guy who changes tons of things at the track--the regular and Sport settings are enough for me. I could also just leave things all stock--just wondering if I don't need any comfort factor since it is not street-driven, am I compromising performance at the track by using the street suspension? Thanks for any feedback.
07-15-2013, 08:54 AM
#2
Race Car
2010 GT3 (non-RS), 11,000 mi; the last half all track. It has GMG Tarmac series suspension components, magnetorheostatic engine mounts and bone-stock shocks. This is essentially a track-only car, trailered to events. Should I increase the spring rates, and if so, should I keep the stock shocks, exchange springs for slightly higher spring rate and leave the rest alone, or change springs and re-valve the shocks OR replace the shocks? I am not the guy who changes tons of things at the track--the regular and Sport settings are enough for me. I could also just leave things all stock--just wondering if I don't need any comfort factor since it is not street-driven, am I compromising performance at the track by using the street suspension? Thanks for any feedback.
07-15-2013, 10:19 AM
#3
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The answer is a function of your needs; your needs and skill level only.
Are you at the point on track that you feel held back by the spring package currently on the car?
When you ask the car to do something, what is happening that you dislike, where is it happening and how would you like to improve it?
Are you at the point on track that you feel held back by the spring package currently on the car?
When you ask the car to do something, what is happening that you dislike, where is it happening and how would you like to improve it?
07-15-2013, 10:35 AM
#4
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I would hire a Pro-Coach, and a Pro-Driver. Spend a day with the two of them, the Pro-Driver to set the benchmark, the Coach to help you improve.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
07-15-2013, 10:42 AM
#5
Rennlist Member
simplest thing to do is to take off stock shocks, send them to billstein for re-valve job and put stiffer springs on. thise way you will retain stock functionality of PASM if you go with anything in the 'reasonably stiff' ballpark like from #450/#600 to #700/#800 you car will still be drivable on the street.
if you decide to go with replacement shocks the sky is the limit. from my experience unless you build a competition car any pro-grade 2-way adjustable shocks will be more than sufficient, you do want to have a possibility to have adjustments on both rebound and compression - like to to keep compression on the softer side and rebound on stiffer side. with spring rates on a custom rebuilt track car you will need to speak with pro people. I went with softer side 600/700 as I also drive car on the street on regular rubber, but if yours is a 100% track toy then you may go with way stiffer setup oriented for slicks, if you intend to use them eventually.
get a ride in a cup car to get an idea of how it goes. it is a bit different perspective when car goes mostly on a tires flex and not on springs, it is fast but it is very different from what you have in a stock car. and you also will probably need more aero downforce if you will try to properly mimic cup car setup.
if you decide to go with replacement shocks the sky is the limit. from my experience unless you build a competition car any pro-grade 2-way adjustable shocks will be more than sufficient, you do want to have a possibility to have adjustments on both rebound and compression - like to to keep compression on the softer side and rebound on stiffer side. with spring rates on a custom rebuilt track car you will need to speak with pro people. I went with softer side 600/700 as I also drive car on the street on regular rubber, but if yours is a 100% track toy then you may go with way stiffer setup oriented for slicks, if you intend to use them eventually.
get a ride in a cup car to get an idea of how it goes. it is a bit different perspective when car goes mostly on a tires flex and not on springs, it is fast but it is very different from what you have in a stock car. and you also will probably need more aero downforce if you will try to properly mimic cup car setup.
Last edited by utkinpol; 07-15-2013 at 11:23 AM.
07-15-2013, 11:52 AM
#6
Rennlist Member
Thread Starter
I think he disappeared into the wheel well, as I haven't seen him since. But I know some of his other friends and I will see if I can locate him. His wife has been worried.
07-15-2013, 11:56 AM
#7
Rennlist Member
Thread Starter
I would hire a Pro-Coach, and a Pro-Driver. Spend a day with the two of them, the Pro-Driver to set the benchmark, the Coach to help you improve.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
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07-15-2013, 12:01 PM
#8
Rennlist Member
Thread Starter
simplest thing to do is to take off stock shocks, send them to billstein for re-valve job and put stiffer springs on. thise way you will retain stock functionality of PASM if you go with anything in the 'reasonably stiff' ballpark like from #450/#600 to #700/#800 you car will still be drivable on the street.
if you decide to go with replacement shocks the sky is the limit. from my experience unless you build a competition car any pro-grade 2-way adjustable shocks will be more than sufficient, you do want to have a possibility to have adjustments on both rebound and compression - like to to keep compression on the softer side and rebound on stiffer side. with spring rates on a custom rebuilt track car you will need to speak with pro people. I went with softer side 600/700 as I also drive car on the street on regular rubber, but if yours is a 100% track toy then you may go with way stiffer setup oriented for slicks, if you intend to use them eventually.
get a ride in a cup car to get an idea of how it goes. it is a bit different perspective when car goes mostly on a tires flex and not on springs, it is fast but it is very different from what you have in a stock car. and you also will probably need more aero downforce if you will try to properly mimic cup car setup.
if you decide to go with replacement shocks the sky is the limit. from my experience unless you build a competition car any pro-grade 2-way adjustable shocks will be more than sufficient, you do want to have a possibility to have adjustments on both rebound and compression - like to to keep compression on the softer side and rebound on stiffer side. with spring rates on a custom rebuilt track car you will need to speak with pro people. I went with softer side 600/700 as I also drive car on the street on regular rubber, but if yours is a 100% track toy then you may go with way stiffer setup oriented for slicks, if you intend to use them eventually.
get a ride in a cup car to get an idea of how it goes. it is a bit different perspective when car goes mostly on a tires flex and not on springs, it is fast but it is very different from what you have in a stock car. and you also will probably need more aero downforce if you will try to properly mimic cup car setup.
07-15-2013, 12:43 PM
#9
Rennlist Member
Anything over about 400# front, 800# rear will need a re-valve. I have 392/672 rates and like them for RA1/NT01 tires, and I did not re-valve.
Unless you know what you are trying to accomplish, I wouldn't make big spring rates changes. The more front rate you add, the more braking becomes important, and you will need to use more of the middle pedal and the LSD to turn the car. You have a LW battery, so your effective front spring rate is already higher than a stock one.
I miss being able to tune shocks at the track, but the stock Bilsteins are pretty darn good. Not to mention, the valving on your .2 dampers are better than the .1's.
Also, stiffer rates will mean more slip angle for the tires, so be prepared to have the car move around more. The rear will change from a progressive to linear, which also means the car will take a set a bit differently, and faster.
Your car is pretty well sorted, and fast, but to be honest, I think your alignment is still what's leaving the most speed on the table. I would first go with a more aggressive alignment and more track time to get used to it. Then re-visit the spring/shock package.
Once you have developed a firm grasp on what kind of alignment you like (or don't like), then I think you can better put some springs/dampers to use, otherwise you may make the care worse for your style.
Look at GT3DE, he's setting national lap records on a bone stock spring/shock setup in a .2GT3. You know the old saying, if it ain't broke....
Unless you know what you are trying to accomplish, I wouldn't make big spring rates changes. The more front rate you add, the more braking becomes important, and you will need to use more of the middle pedal and the LSD to turn the car. You have a LW battery, so your effective front spring rate is already higher than a stock one.
I miss being able to tune shocks at the track, but the stock Bilsteins are pretty darn good. Not to mention, the valving on your .2 dampers are better than the .1's.
Also, stiffer rates will mean more slip angle for the tires, so be prepared to have the car move around more. The rear will change from a progressive to linear, which also means the car will take a set a bit differently, and faster.
Your car is pretty well sorted, and fast, but to be honest, I think your alignment is still what's leaving the most speed on the table. I would first go with a more aggressive alignment and more track time to get used to it. Then re-visit the spring/shock package.
Once you have developed a firm grasp on what kind of alignment you like (or don't like), then I think you can better put some springs/dampers to use, otherwise you may make the care worse for your style.
Look at GT3DE, he's setting national lap records on a bone stock spring/shock setup in a .2GT3. You know the old saying, if it ain't broke....
07-15-2013, 01:19 PM
#10
Rennlist Member
be aware stock springs are not linear, and I would think twice before going into linear springs with a huge split like #400/#800. mechanic I work with believes strongly any 997 chassis does not benefit much from any split larger than #100 between front/rear. opinions on this topic differ a lot.
I would think talking to bilstein is a good first step, check with them on what they would recommend and proceed with what you think is right for you.
I would think talking to bilstein is a good first step, check with them on what they would recommend and proceed with what you think is right for you.
07-15-2013, 02:33 PM
#11
Rennlist Member
be aware stock springs are not linear, and I would think twice before going into linear springs with a huge split like #400/#800. mechanic I work with believes strongly any 997 chassis does not benefit much from any split larger than #100 between front/rear. opinions on this topic differ a lot.
I would think talking to bilstein is a good first step, check with them on what they would recommend and proceed with what you think is right for you.
I would think talking to bilstein is a good first step, check with them on what they would recommend and proceed with what you think is right for you.
TPC racing/Mike Levitas has chassis recommendations for track setup that are on point IMO. The RS, which is wider than the normal GT3 can use a slightly larger split than the non-RS, as it has more natural understeer because of J-Lo booty. I decreased the factory split by 100# and it works very well for me. Stock battery, side muffler delete help round out the balance even more.
I still think the OP needs to play with the alignment, learn more about how those changes affect the car, then play with a spring package. Cass Whitehead and Jon Lewis will tell you the same thing.
07-15-2013, 02:46 PM
#12
Rennlist Member
I would agree, prior to messing up existing suspension it is very advisable to get a very clear understanding of what specifically you want to change and why. especially considering level of refinement '10 RS car comes with in stock trim.
07-15-2013, 02:48 PM
#13
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Rennlist Member
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The KW racing suspension used by Olaf at the Ring has several hundreds lbs/in difference between front and rear axle.
The Ohlins (one of the best kits for the 997) also has a gigantic split.
Front suspension has struts (near 1.0 wheel rate) , rear is a multi-link, wheel rates are radically different. Then comes corner weights minus unsprung weight, then toe curves, then sway bars stiffness per axle, lots of considerations to make a straight recommendation.
The 997.1 GT3 was a mess on the shocks tuning, but the 997.2 GT3 is so good that I would not touch it. Work on making the car lighter, by removing the heavy side mufflers, run good 18" wheels and tires, minor aero improvements, good seats, a LW Li-Ion batter, PCCB, quality LSD, and the monoballs on the suspension links.
The most I would do to a 997.2 GT3 for springs is adding another 150# to the front, and reset everything else through sway bars and alignment.
Lap times will not change with such minimal gains, lap times do change drastically with proper training and lots of seat time.
Come to Florida in Winter time, we get dry track days, and you get a feeling for what a GT3 can do.
The Ohlins (one of the best kits for the 997) also has a gigantic split.
Front suspension has struts (near 1.0 wheel rate) , rear is a multi-link, wheel rates are radically different. Then comes corner weights minus unsprung weight, then toe curves, then sway bars stiffness per axle, lots of considerations to make a straight recommendation.
The 997.1 GT3 was a mess on the shocks tuning, but the 997.2 GT3 is so good that I would not touch it. Work on making the car lighter, by removing the heavy side mufflers, run good 18" wheels and tires, minor aero improvements, good seats, a LW Li-Ion batter, PCCB, quality LSD, and the monoballs on the suspension links.
The most I would do to a 997.2 GT3 for springs is adding another 150# to the front, and reset everything else through sway bars and alignment.
Lap times will not change with such minimal gains, lap times do change drastically with proper training and lots of seat time.
Come to Florida in Winter time, we get dry track days, and you get a feeling for what a GT3 can do.
07-15-2013, 04:31 PM
#14
Race Director
I would hire a Pro-Coach, and a Pro-Driver. Spend a day with the two of them, the Pro-Driver to set the benchmark, the Coach to help you improve.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
Suspension gains from shocks and springs on a car so well tuned as a 997.2 GT3 are hard to show up. Just look at the extensive work the GT3Cup teams go through shocks tuning, while keeping the same spring rates, countless hours of tuning to make the cars better, for that track, on that day, with those drivers.
The tires you use will affect the ideal spring rates as well. Generally, GT3 have too soft springs in the front, they come setup for fast road driving, but not for racetrack use.
The Pro-Coach and Pro-Driver can also make recommendations on suspension settings, then work with a shop to perform installation and tuning.
Shock/Springs don't make a GT3 better just by throwing in parts, it takes a lot of time on tuning, and some shops claim they have the secret sauce, something where they have invested significant time.
...or you can just throw in stiffer springs over the internet.
On stock shocks and springs I have witnessed .2 GT3 and GT3 RS run impressive lap times, and no complains from the drivers.
If you have a GT3, work the driver, then work the car. If you have a lousy track car (a Fiat, Lambo, FR-S, old Cayman), work the car first.
07-15-2013, 11:54 PM
#15
Rennlist Member
Thread Starter
Anything over about 400# front, 800# rear will need a re-valve. I have 392/672 rates and like them for RA1/NT01 tires, and I did not re-valve.
Unless you know what you are trying to accomplish, I wouldn't make big spring rates changes. The more front rate you add, the more braking becomes important, and you will need to use more of the middle pedal and the LSD to turn the car. You have a LW battery, so your effective front spring rate is already higher than a stock one.
I miss being able to tune shocks at the track, but the stock Bilsteins are pretty darn good. Not to mention, the valving on your .2 dampers are better than the .1's.
Also, stiffer rates will mean more slip angle for the tires, so be prepared to have the car move around more. The rear will change from a progressive to linear, which also means the car will take a set a bit differently, and faster.
Your car is pretty well sorted, and fast, but to be honest, I think your alignment is still what's leaving the most speed on the table. I would first go with a more aggressive alignment and more track time to get used to it. Then re-visit the spring/shock package.
Once you have developed a firm grasp on what kind of alignment you like (or don't like), then I think you can better put some springs/dampers to use, otherwise you may make the care worse for your style.
Look at GT3DE, he's setting national lap records on a bone stock spring/shock setup in a .2GT3. You know the old saying, if it ain't broke....
Unless you know what you are trying to accomplish, I wouldn't make big spring rates changes. The more front rate you add, the more braking becomes important, and you will need to use more of the middle pedal and the LSD to turn the car. You have a LW battery, so your effective front spring rate is already higher than a stock one.
I miss being able to tune shocks at the track, but the stock Bilsteins are pretty darn good. Not to mention, the valving on your .2 dampers are better than the .1's.
Also, stiffer rates will mean more slip angle for the tires, so be prepared to have the car move around more. The rear will change from a progressive to linear, which also means the car will take a set a bit differently, and faster.
Your car is pretty well sorted, and fast, but to be honest, I think your alignment is still what's leaving the most speed on the table. I would first go with a more aggressive alignment and more track time to get used to it. Then re-visit the spring/shock package.
Once you have developed a firm grasp on what kind of alignment you like (or don't like), then I think you can better put some springs/dampers to use, otherwise you may make the care worse for your style.
Look at GT3DE, he's setting national lap records on a bone stock spring/shock setup in a .2GT3. You know the old saying, if it ain't broke....