Understeering RS and GT3
05-11-2007, 10:17 AM
#16
Originally Posted by Racerron
For all those who say that the RS is a great track car and that they or GT3's do not understeer, then I suggest you find the right pedal on the far right, that is the one to the right of the brake. Up to 7/10's the car is fine but still not as pointey as a 996 GT3, but beyond that it understeers like an FWD straight from the dealer. Sorry to all the race Honda CRX drivers, (those cars would eat an RS alive on a track like Calabogie) as I'm sure Jason's (AKA Noble GT) Exige would. 
if you are at the track with me come and try it.
i dont even have the track pack only stock suspension....i cant imagine how good it is with ohlins or nitrons
05-11-2007, 10:19 AM
#17
Originally Posted by Racerron
For all those who say that the RS is a great track car and that they or GT3's do not understeer, then I suggest you find the right pedal on the far right, that is the one to the right of the brake. Up to 7/10's the car is fine but still not as pointey as a 996 GT3, but beyond that it understeers like an FWD straight from the dealer. Sorry to all the race Honda CRX drivers, (those cars would eat an RS alive on a track like Calabogie) as I'm sure Jason's (AKA Noble GT) Exige would.
05-11-2007, 10:32 AM
#18
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Mitch - Pilot Sport Cups 19 inch N spec. These tires have much bigger grooves and surely give up some dry grip compared to the regular cup tires.
Mike! See you tomorrow. I will not come early as I am not a fan of the short track. I will be curius to try the new alignment. neg 2.5 in front neg 2 in back. Zero toe front, 32 mins in back. Unless I have forgotten, more camber in front, less camber in back reduces understeer. Less toe in front and more toe in back also reduce understeer. We'll see. Rus will be there with the Z06 which has been "tuned" by John Powell - gonna be stupid fast.
If JF is around I will certainly seek his help. A gys who has won the Rolex Daytona twice in a row has to know something about setup!
Best,
Mike! See you tomorrow. I will not come early as I am not a fan of the short track. I will be curius to try the new alignment. neg 2.5 in front neg 2 in back. Zero toe front, 32 mins in back. Unless I have forgotten, more camber in front, less camber in back reduces understeer. Less toe in front and more toe in back also reduce understeer. We'll see. Rus will be there with the Z06 which has been "tuned" by John Powell - gonna be stupid fast.
If JF is around I will certainly seek his help. A gys who has won the Rolex Daytona twice in a row has to know something about setup!
Best,
05-11-2007, 11:31 AM
#19
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Originally Posted by Bob Rouleau
Less toe in front and more toe in back also reduce understeer.
bob,
less toe in at the rear improves rotation at the expense of high speed stability especially under braking. if 32' rear toe is total then it leans towards stability. if per wheel then its a lot. good luck with the setup and keep us posted.
05-11-2007, 11:50 AM
#20
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I found the RS very easy to steer with the gas, something a bone stock 996 GT3 couldn't do that well. It pushed on a 45mph turn on corner exit, but the car was on stock alignment.
The more planted rear end could be related to softer springs, as the rear end feel softer than the 996 GT3, hence the factory bar setting at full stiff. In this case with 415Hp on mid corner and corner exit, the car will squat, the front end will get light, and the car will push.
Understeer/Oversteer is a matter of car setup. My 996 GT3 had a lot of understeer from the factory.
It makes sense that Porsche sets the road car with understeer at fast corners, to keep the average drivers on the road.
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
The more planted rear end could be related to softer springs, as the rear end feel softer than the 996 GT3, hence the factory bar setting at full stiff. In this case with 415Hp on mid corner and corner exit, the car will squat, the front end will get light, and the car will push.
Understeer/Oversteer is a matter of car setup. My 996 GT3 had a lot of understeer from the factory.
It makes sense that Porsche sets the road car with understeer at fast corners, to keep the average drivers on the road.
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
05-11-2007, 12:31 PM
#21
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Originally Posted by NJ-GT
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
my understanding is that with shims you can only get about -2deg. camber at the front and that's why people resort to rotating the tops.
05-11-2007, 12:37 PM
#22
Originally Posted by NJ-GT
I found the RS very easy to steer with the gas, something a bone stock 996 GT3 couldn't do that well. It pushed on a 45mph turn on corner exit, but the car was on stock alignment.
The more planted rear end could be related to softer springs, as the rear end feel softer than the 996 GT3, hence the factory bar setting at full stiff. In this case with 415Hp on mid corner and corner exit, the car will squat, the front end will get light, and the car will push.
Understeer/Oversteer is a matter of car setup. My 996 GT3 had a lot of understeer from the factory.
It makes sense that Porsche sets the road car with understeer at fast corners, to keep the average drivers on the road.
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
The more planted rear end could be related to softer springs, as the rear end feel softer than the 996 GT3, hence the factory bar setting at full stiff. In this case with 415Hp on mid corner and corner exit, the car will squat, the front end will get light, and the car will push.
Understeer/Oversteer is a matter of car setup. My 996 GT3 had a lot of understeer from the factory.
It makes sense that Porsche sets the road car with understeer at fast corners, to keep the average drivers on the road.
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
Anyway, I can attest to the fact that, withy some simple setup adjustments, the car balances itself very nicely:
"circuit" alignment settings (with a tad less front camber to taste)
increase front camber with shims (no need to rotate the tops)
minimum ride height in spec
265 Sport Cups on the front (not N rated, but no problem)
full soft on the front
stock (full stiff) on the rear
tire pressures up to 38 hot (give or take to preference)
The max spec rear toe for the circuit settings is working well for me and I agree the spring rates just don't make sense -- too soft and the bars aren't matched front to rear (or they wouldn't be at opposite settings.)
The fundamental design of the 997 is the same, but the rear suspension geometry is different, if only in minor tweaks.
While I don't count the RS as a "bargain," if you want the wide body and no sunroof, it's fair value.
05-11-2007, 06:36 PM
#23
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Originally Posted by NJ-GT
Solutions:
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
- Increase front track (using shims), and get both more negative camber and more caster. This is better than rotating the tops.
- Run a wider Front tire. I saw a 997S with 275 Nittos NT01 at the front last week.
- Less bar at the front. Personally, I would prefer to increase bar, and balance the spring rates.
Do not reduce rear toe, unless you want to visit the Armco. The suspension design on the 997 is identical to the 996. Under load, the rear wheels tend to toe-out so it's necessary to set enough static toe-in.
The RS is a great car, and a bargain.
Additionally, I consider it naive to go to the track with the alignment as it comes from the factory (specially a GT3). It makes a BIG difference to dial proper camber in the front. I have never driven a street/track car out of the dealer before it being setup properly for my specs.
Don't go the big front tire route NJ-GT. It might work in his Monster GT3 b/c it has adjustable-everything. My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
Keep the same tire sizes, and just put as much camber up front as you can and it should be OK. it obvious to expect understeer in a 911 if you are too hard on the gas before unwinding the wheel...
05-11-2007, 06:53 PM
#24
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Originally Posted by cgomez
Agree on some suggestions, I don't see why the GT3 (RS or not) can be so different geometrically than a 997S. The 997 is a beatifully balanced platform where weight trasnfer is key make the car do wathever you want.
Additionally, I consider it naive to go to the track with the alignment as it comes from the factory (specially a GT3). It makes a BIG difference to dial proper camber in the front. I have never driven a street/track car out of the dealer before it being setup properly for my specs.
Don't go the big front tire route NJ-GT. It might work in his Monster GT3 b/c it has adjustable-everything. My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
Keep the same tire sizes, and just put as much camber up front as you can and it should be OK. it obvious to expect understeer in a 911 if you are too hard on the gas before unwinding the wheel...
Additionally, I consider it naive to go to the track with the alignment as it comes from the factory (specially a GT3). It makes a BIG difference to dial proper camber in the front. I have never driven a street/track car out of the dealer before it being setup properly for my specs.
Don't go the big front tire route NJ-GT. It might work in his Monster GT3 b/c it has adjustable-everything. My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
Keep the same tire sizes, and just put as much camber up front as you can and it should be OK. it obvious to expect understeer in a 911 if you are too hard on the gas before unwinding the wheel...
05-11-2007, 06:59 PM
#25
Originally Posted by cgomez
Agree on some suggestions, I don't see why the GT3 (RS or not) can be so different geometrically than a 997S. The 997 is a beatifully balanced platform where weight trasnfer is key make the car do wathever you want.
Additionally, I consider it naive to go to the track with the alignment as it comes from the factory (specially a GT3). It makes a BIG difference to dial proper camber in the front. I have never driven a street/track car out of the dealer before it being setup properly for my specs.
Don't go the big front tire route NJ-GT. It might work in his Monster GT3 b/c it has adjustable-everything. My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
Keep the same tire sizes, and just put as much camber up front as you can and it should be OK. it obvious to expect understeer in a 911 if you are too hard on the gas before unwinding the wheel...
Additionally, I consider it naive to go to the track with the alignment as it comes from the factory (specially a GT3). It makes a BIG difference to dial proper camber in the front. I have never driven a street/track car out of the dealer before it being setup properly for my specs.
Don't go the big front tire route NJ-GT. It might work in his Monster GT3 b/c it has adjustable-everything. My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
Keep the same tire sizes, and just put as much camber up front as you can and it should be OK. it obvious to expect understeer in a 911 if you are too hard on the gas before unwinding the wheel...
It seems to me if you stopped "see sawing" the wheel, your car would have a better chance of taking a set and holding a line.
It seems like you've got a feel for low speed trailing throttle oversteer. I'd suggest taking off the gardening gloves and consciously keeping your hands in a fixed position on the wheel (don't drop a hand to the bottom of the wheel) and being careful to smooth out and avoid the see-saw and jabbing, then use the throttle to steer through the apex. I sometimes use 3rd gear, where 2nd might be available, just to take some of the immediacy out of the engine so I can concentrate on smooth control inputs.
As for wide rubber up front, keep in mind the GT3 rears are larger 305's already.
If you dial in too much camber in the fronts, the car will just ride on the shoulders and never load up enough, especially in the front, to work the tire. There's a lot more to getting a GT3 set up than front camber.
I'm not encouraging people to go to 265's without deciding on the trade-offs. But they give a better contact patch for braking, they make the car more responsive, especially on long, fast sweepers and I like the steering feel. The downside for me is the GT3 roll stiffness is too soft and the PASM needs to run on Sport to keep the body under control, but that induces some "skate" where the wheels aren't allowed to follow the road surface as well and the tires are taking more of the work, but they're bloody 19's, so there's problems with stiff sidewalls (as well as potential damage if the suspension doesn't soak up riding over a berm f'rinstance.)
And the GT3 rear end is not the same as the Carrera in geometry or tune.
05-11-2007, 07:23 PM
#27
Originally Posted by grussell
Does anyone have the ride height specs? Is there a Min - Max?
https://rennlist.com/forums/showpost...0&postcount=12
05-11-2007, 08:26 PM
#28
Rennlist Member
Originally Posted by Carrera GT
It would be interesting to watch your video without the music track.
It seems to me if you stopped "see sawing" the wheel, your car would have a better chance of taking a set and holding a line.
It seems like you've got a feel for low speed trailing throttle oversteer. I'd suggest taking off the gardening gloves and consciously keeping your hands in a fixed position on the wheel (don't drop a hand to the bottom of the wheel) and being careful to smooth out and avoid the see-saw and jabbing, then use the throttle to steer through the apex. I sometimes use 3rd gear, where 2nd might be available, just to take some of the immediacy out of the engine so I can concentrate on smooth control inputs.
As for wide rubber up front, keep in mind the GT3 rears are larger 305's already.
If you dial in too much camber in the fronts, the car will just ride on the shoulders and never load up enough, especially in the front, to work the tire. There's a lot more to getting a GT3 set up than front camber.
I'm not encouraging people to go to 265's without deciding on the trade-offs. But they give a better contact patch for braking, they make the car more responsive, especially on long, fast sweepers and I like the steering feel. The downside for me is the GT3 roll stiffness is too soft and the PASM needs to run on Sport to keep the body under control, but that induces some "skate" where the wheels aren't allowed to follow the road surface as well and the tires are taking more of the work, but they're bloody 19's, so there's problems with stiff sidewalls (as well as potential damage if the suspension doesn't soak up riding over a berm f'rinstance.)
And the GT3 rear end is not the same as the Carrera in geometry or tune.
It seems to me if you stopped "see sawing" the wheel, your car would have a better chance of taking a set and holding a line.
It seems like you've got a feel for low speed trailing throttle oversteer. I'd suggest taking off the gardening gloves and consciously keeping your hands in a fixed position on the wheel (don't drop a hand to the bottom of the wheel) and being careful to smooth out and avoid the see-saw and jabbing, then use the throttle to steer through the apex. I sometimes use 3rd gear, where 2nd might be available, just to take some of the immediacy out of the engine so I can concentrate on smooth control inputs.
As for wide rubber up front, keep in mind the GT3 rears are larger 305's already.
If you dial in too much camber in the fronts, the car will just ride on the shoulders and never load up enough, especially in the front, to work the tire. There's a lot more to getting a GT3 set up than front camber.
I'm not encouraging people to go to 265's without deciding on the trade-offs. But they give a better contact patch for braking, they make the car more responsive, especially on long, fast sweepers and I like the steering feel. The downside for me is the GT3 roll stiffness is too soft and the PASM needs to run on Sport to keep the body under control, but that induces some "skate" where the wheels aren't allowed to follow the road surface as well and the tires are taking more of the work, but they're bloody 19's, so there's problems with stiff sidewalls (as well as potential damage if the suspension doesn't soak up riding over a berm f'rinstance.)
And the GT3 rear end is not the same as the Carrera in geometry or tune.
http://axisofoversteer.blogspot.com/...oversteer.html
https://rennlist.com/forums/racing-and-drivers-education-forum/350753-pocono-east-what-a-fun-track-day.html
All of those that know me, know I don't usually drive like that. The seesaw is anticipation of what the car is about to do (oversteer) and correction for constant changes in grip when you are at the limit...... but I'm not willing to convert this thread into the "DE smooth" discussion that has been overly beaten many times.
My main point for posting the video is to show that a 911 (and any good sportscar) can be easily driven/tuned to either over or understeer... it is mostly up to the driver...
This is how I usually drive for good laptimes:
http://axisofoversteer.com/blog/movies/carlosLRP101.wmv
Last edited by cgomez; 05-12-2007 at 12:33 AM.
05-11-2007, 09:18 PM
#29
Burning Brakes
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Originally Posted by cgomez
My 997S becomes an oversteer Mayhem with too much grip in the front:
http://axisofoversteer.com/blog/movies/oversteer.mov
http://axisofoversteer.com/blog/movies/oversteer.mov
Hahaha certainly looks like you had fun and burnt your fair share of $ in tires
While I never raced cars I have raced 2stroke shifter karts, 250cc Motorcross and Downhill Mountain Biking AND with all three disciplines it is expected that when you purchase the frame, fork etc that you go and get it tuned to your weight, riding style, preference, preload, damping, rebound etc. The difference in performance afterwards was night and day! The rear tire stayed glued to the rocks, the front end planted and the suspension did what it suppose to do-it kept me 'suspended' so I could concentrate on shifting, jumps, drops, berms etc.
So if I were to buy a GT3 or a RS and think of tracking it-FIRST thing would be setup and trial&error for a week. It goes with the territory, it's a given, if you want to race you set your car up to what suits you.
Hell sometimes I would rebuild my suspension after every race with new valves, stacks, different oil weights and nitrogen to get that advantage.
So Ron, instead of bad mouthing this and that, spend some time setting that sweet car up. If other people (read: a lot!) are racing 997 GT3 variants and having success, I'm sure you can too!...Because it sounds like people that know you, know you are experienced. So go out, spend a bit more $ and give 'er hell!
05-11-2007, 09:30 PM
#30
Originally Posted by cgomez
Thanks for the advice, but the main reason for those oversteer moments was a leaking right rear wheel. Some of those moments were then induced and sutained on purpose, just for kicks...:
http://axisofoversteer.blogspot.com/...oversteer.html
https://rennlist.com/forums/showthread.php?t=350753
All of those that know me, know I don't usually drive like that. The seesaw is anticipation of what the car is about to do (oversteer) and correction for constant changes in grip when you are at the limit...... but I'm not willing to convert this thread into the "DE smooth" discussion that has been overly beaten many times.
http://axisofoversteer.blogspot.com/...oversteer.html
https://rennlist.com/forums/showthread.php?t=350753
All of those that know me, know I don't usually drive like that. The seesaw is anticipation of what the car is about to do (oversteer) and correction for constant changes in grip when you are at the limit...... but I'm not willing to convert this thread into the "DE smooth" discussion that has been overly beaten many times.