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Question on ride height

 
Old 02-24-2012, 10:14 AM
  #46  
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If you are taking advice from RS owners, you will mess yourself up. The setup characteristics between a 997.1 GT3 and a 997.1 GT3 RS are different because of the RS wider track width. The same with the later 997.2 GT3's or RS's. They are simply different

A neutral handling 997.1 GT3 (non RS) is easily accomplished by simply changing the rear bar to the center hole, assuming you haven't changed anything else. This is with the track alignment settings in the owners manual.

I have made this suggestion to several GT3 owners at the track that had very nervous cars. It hasn't failed to work yet.

Good luck to you!
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Old 02-24-2012, 10:57 AM
  #47  
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Ahhh I'm getting a little lost in set up.

Car is 997.1 GT3
Here are my current settings:
Tire MPSC. 235 F 305R 19in wheels
Ride Height 108mm F 133mmR
Camber: -2.2F -2.4R
Toe: 0.5mm out each side Front, 2.5mm in each side Rear
Rear Sway Middle
Front Sway One from Full soft.
Have Guard LSD and drive with TC off

I am not happy with how the car drove today. Rear felt really loose on turn in and exit, but at the same time I couldn't get the car rotated enough. Adding steering lock would just break the rear.

I've been fiddling with my set up for months now but I think I've gotten a bit lost.

Edit

I was at 99mm front ride height, sway bar at middle front and rear, and 2.2 camber all around. I went to the above set up to give me a stronger rear end.
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Old 02-24-2012, 11:59 AM
  #48  
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Originally Posted by bmardini View Post
Ahhh I'm getting a little lost in set up.

Car is 997.1 GT3
Here are my current settings:
Tire MPSC. 235 F 305R 19in wheels
Ride Height 108mm F 133mmR
Camber: -2.2F -2.4R
Toe: 0.5mm out each side Front, 2.5mm in each side Rear
Rear Sway Middle
Front Sway One from Full soft.
Have Guard LSD and drive with TC off

I am not happy with how the car drove today. Rear felt really loose on turn in and exit, but at the same time I couldn't get the car rotated enough. Adding steering lock would just break the rear.

I've been fiddling with my set up for months now but I think I've gotten a bit lost.

Edit

I was at 99mm front ride height, sway bar at middle front and rear, and 2.2 camber all around. I went to the above set up to give me a stronger rear end.
I'd put your front sway one hole stiffer, add some more front camber. Drop the rear 5mm more, or adjust the car to Rad's suggestion of 100/120...both give a 20mm rake, which will give some stability. With your current camber, sounds like it's forcing you to add alot more steering angle to overcome the massive amount of rear grip you have.

Your LSD is what is causing some of the oversteer on exit (along with steering angle), as it should be locked up if you are buried deep into the throttle. Open the wheel up as quick as possible, which will be easier to do if you can get the car to the apex in the first place. From what you've described, I'm guessing you have big mid-corner push.
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Old 02-24-2012, 03:44 PM
  #49  
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Originally Posted by Mvez View Post
I'd put your front sway one hole stiffer, add some more front camber. Drop the rear 5mm more, or adjust the car to Rad's suggestion of 100/120...both give a 20mm rake, which will give some stability. With your current camber, sounds like it's forcing you to add alot more steering angle to overcome the massive amount of rear grip you have.

Your LSD is what is causing some of the oversteer on exit (along with steering angle), as it should be locked up if you are buried deep into the throttle. Open the wheel up as quick as possible, which will be easier to do if you can get the car to the apex in the first place. From what you've described, I'm guessing you have big mid-corner push.
What you say makes sense, I had the car at 2.2F 1.7R, with middle holes on both sways, and it felt nicer, but the 99mm/135mm ride height showed oversteer so I wound up going for more rear camber. Then the shop I work with wants me to have a lot of camber at the rear, but I think he is treating my road car too much like a Cup car.

The more I think about it the more I agree with you - rotation is rotation, and my natural tendency is to rotate the car any way possible, but if the set up is not cooperating then I can't open the car up on exit properly, and thus am scared to put the power down because in 2nd/3rd gear you do run the risk of the rear snapping, especially if you hit an exit curb.

Will give it a shot. Any other suggestions welcome!
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Old 02-24-2012, 04:32 PM
  #50  
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Originally Posted by bmardini View Post
What you say makes sense, I had the car at 2.2F 1.7R, with middle holes on both sways, and it felt nicer, but the 99mm/135mm ride height showed oversteer so I wound up going for more rear camber. Then the shop I work with wants me to have a lot of camber at the rear, but I think he is treating my road car too much like a Cup car.

The more I think about it the more I agree with you - rotation is rotation, and my natural tendency is to rotate the car any way possible, but if the set up is not cooperating then I can't open the car up on exit properly, and thus am scared to put the power down because in 2nd/3rd gear you do run the risk of the rear snapping, especially if you hit an exit curb.

Will give it a shot. Any other suggestions welcome!
You can run -2.4 rear, but you need to be driving really hard, and running about -3 up front, if you want the car to turn.

As suggested by others, all you probably had to do from your previous setup was loosen the rear sway by 1 hole (or firm the front by 1 hole), or drop the rear about 5-10mm, and run with a 99-100mm/120-125 setup and that probably would've been fine, assuming your tire wear was pretty even with -2.2/-1.7 camber.

For much better rear tire wear, I'd instead drop your rear camber back to -1.8 to -2, drop the rear by 5-8mm (or drop to 100/120), put sways in the middle and then test. THEN use your bars to adjust the attitude of the car before you go and completey re-do the suspension again. Bars are free adjustments....they don't cost you anything, and you can do them at the track for immediate feedback.

I like to set my cars up so that the bars are typically somewhere in the middle at both ends, this way, I get plenty of "free" adjustment range at the track with either bar or tire pressure settings. As temps, tires, and tracks change, usually, you can get the car back where you want it for the weekend, if you have adjustment both ways on your bars.
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Old 02-25-2012, 03:28 AM
  #51  
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Originally Posted by Mvez View Post
You can run -2.4 rear, but you need to be driving really hard, and running about -3 up front, if you want the car to turn.

As suggested by others, all you probably had to do from your previous setup was loosen the rear sway by 1 hole (or firm the front by 1 hole), or drop the rear about 5-10mm, and run with a 99-100mm/120-125 setup and that probably would've been fine, assuming your tire wear was pretty even with -2.2/-1.7 camber.

For much better rear tire wear, I'd instead drop your rear camber back to -1.8 to -2, drop the rear by 5-8mm (or drop to 100/120), put sways in the middle and then test. THEN use your bars to adjust the attitude of the car before you go and completey re-do the suspension again. Bars are free adjustments....they don't cost you anything, and you can do them at the track for immediate feedback.

I like to set my cars up so that the bars are typically somewhere in the middle at both ends, this way, I get plenty of "free" adjustment range at the track with either bar or tire pressure settings. As temps, tires, and tracks change, usually, you can get the car back where you want it for the weekend, if you have adjustment both ways on your bars.
Cool man. I'll go back to what felt better. In truth I think I'm mis-interpreting what the car is doing; I'm reading oversteer but it might be because I'm fighting understeer without realizing it.

My current set-up reads like understeer-central - I haven't seen a single set-up on RL where anyone has more camber in the rear than the front.
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Old 02-25-2012, 09:06 AM
  #52  
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Track cold psi?
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Old 02-26-2012, 03:10 PM
  #53  
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Originally Posted by speedyralph View Post
Track cold psi?
This has been discussed alot before. But basics would be:

Short Sessions colder days
- expect psi to raise about +(4-6)
- I always start outside wheels 1psi lower (left side on clockwise tracks)
- more right turns = more load on left tires = more heat

Mid length sessions warm days
- expect psi to go up about +8

Hot days, GT3s playing chase for 30+ minute
- expect psi to rise +(9-12) from cold

You work back from the +(4-6), +8, +(9-12)
- you also bleed as the day goes on

For most popular type tires, most people seem to aim for Hot temps
- Front 31-36
- Rear 35-40

My personal like is Front 32-33, Rear 35-37 Hot

The starting cold psi thus has an enormous range given the session, length, temp and speed you are driving:
- I remember a day when I started the fronts at 21
- I also remember days that I started them at 32

Also remember as the day goes on you never return to cold if it is a warm day so really starting temps don't work for me - I just bleed the tires down immediately after a session to where I want them Hot and I don't worry about starting temps at all - not even the slightest.

Last edited by 997gt3north; 02-26-2012 at 11:16 PM.
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Old 02-26-2012, 06:42 PM
  #54  
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997gt3north > You are the man, Thanks!!
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Old 02-26-2012, 06:44 PM
  #55  
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Originally Posted by mdrums View Post
Ill be there...1st time at Homestead...hope to meet you
Did you like the track? I didn't get a chance to come up to you, but that was me on the white #17 GT3.

Ralph
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Old 02-26-2012, 08:22 PM
  #56  
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I agree with ralph on this one GT3North and NJ-GT have been very informative on this forum in the way of suspension teachings. I have learned many things from them among others and I am most thankful of their contriburtions on the board. Just amazing input
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Old 02-26-2012, 11:25 PM
  #57  
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Originally Posted by lawjdc View Post
If you are taking advice from RS owners, you will mess yourself up. The setup characteristics between a 997.1 GT3 and a 997.1 GT3 RS are different because of the RS wider track width. The same with the later 997.2 GT3's or RS's. They are simply different

A neutral handling 997.1 GT3 (non RS) is easily accomplished by simply changing the rear bar to the center hole, assuming you haven't changed anything else. This is with the track alignment settings in the owners manual.

I have made this suggestion to several GT3 owners at the track that had very nervous cars. It hasn't failed to work yet.

Good luck to you!
I would just like to say that I entirely disagree with this for my personal preference on my narrow body 997.mk1 - but this highlights how everyone likes a different setup and thus there is no answer to this question - you have to figure out what works for you on the tracks you drive and the tires you use. Also, if you have fixed / changed the LSD, I have a Guard 50/80, it also changes the equation.
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Old 02-28-2012, 10:48 AM
  #58  
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Thanks to everybodies input and advice. I had a stellar and safe weekend at Homestead Speedway.

I will concentrate on selling this car in order to put an offer on Fritz car.

Thank You and big thanks to Rennlist for providing a kick *** forums!
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