Understeering issues with 997S
07-23-2012, 12:40 PM
#62
Rennlist Member
you have resurrected a very old thread. 
most of folks there moved to gt3 cars long time ago.
i would recommend to spend a bit more and get both matching gt3 bars if you really want to go down that road.
also, it (IMHO) only makes sense if you also already got GT3 LCAs installed and camber level is set to -2deg area (like -2.5f -2r) and you still want to do additional adjustments.
I had only rear gt3 bar installed and i did not quite like how front behaved in the turns. what you achieve with both gt3 bars set to middle is minimization of car tilt in the mid-turn so essentially you do not improve corner entry grip but you improve mid-corner stability and corner exit speed.
it is a bit counter intuitive as for AX best grip you want to minimize understeer in low-speed corner entry with a softer front sway bar and stiffer rear, but for track setup it becomes more critical to optimize mid-corner stability with both stiffer sway bars, front and rear, and those bars should be set accurately for both rear and front to tilt as similar rate so you would not loose grip at your heavy *** at mid-corner.
then you deal with understeer of front axle at corner entry by using trailbraking and overall handling of your suspension pre-loading side what needs to have grip and then maitaining this load while you steer to the apex, so it is all about overall balance.
beleive or not, stock car is neutral enough. it just has way to much 'rocking' movement and that is getting eliminated with stiffer sway bars so under load contact patch on your tires not getting moved all the way out to the outer edge of the tire.
install of the front sway bar is a moderately complicated DIY - i got it done at the shop as it requires to unbolt crossmember and, well, it is doable but not very simpe if you have no proper lift in your garage.
rear bar is very simple to replace.
go to tarett.com or give thema call and ask about all existing versions of sway bars for GT3 as there are more than one version and you want to have a matching set.
http://www.tarett.com/items/996-997-...links/list.htm
most of folks there moved to gt3 cars long time ago.i would recommend to spend a bit more and get both matching gt3 bars if you really want to go down that road.
also, it (IMHO) only makes sense if you also already got GT3 LCAs installed and camber level is set to -2deg area (like -2.5f -2r) and you still want to do additional adjustments.
I had only rear gt3 bar installed and i did not quite like how front behaved in the turns. what you achieve with both gt3 bars set to middle is minimization of car tilt in the mid-turn so essentially you do not improve corner entry grip but you improve mid-corner stability and corner exit speed.
it is a bit counter intuitive as for AX best grip you want to minimize understeer in low-speed corner entry with a softer front sway bar and stiffer rear, but for track setup it becomes more critical to optimize mid-corner stability with both stiffer sway bars, front and rear, and those bars should be set accurately for both rear and front to tilt as similar rate so you would not loose grip at your heavy *** at mid-corner.
then you deal with understeer of front axle at corner entry by using trailbraking and overall handling of your suspension pre-loading side what needs to have grip and then maitaining this load while you steer to the apex, so it is all about overall balance.
beleive or not, stock car is neutral enough. it just has way to much 'rocking' movement and that is getting eliminated with stiffer sway bars so under load contact patch on your tires not getting moved all the way out to the outer edge of the tire.
install of the front sway bar is a moderately complicated DIY - i got it done at the shop as it requires to unbolt crossmember and, well, it is doable but not very simpe if you have no proper lift in your garage.
rear bar is very simple to replace.
go to tarett.com or give thema call and ask about all existing versions of sway bars for GT3 as there are more than one version and you want to have a matching set.
http://www.tarett.com/items/996-997-...links/list.htm
07-23-2012, 01:20 PM
#63
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Join Date: Mar 2007
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you have resurrected a very old thread. most of folks there moved to gt3 cars long time ago.
i would recommend to spend a bit more and get both matching gt3 bars if you really want to go down that road.
also, it (IMHO) only makes sense if you also already got GT3 LCAs installed and camber level is set to -2deg area (like -2.5f -2r) and you still want to do additional adjustments.
I had only rear gt3 bar installed and i did not quite like how front behaved in the turns. what you achieve with both gt3 bars set to middle is minimization of car tilt in the mid-turn so essentially you do not improve corner entry grip but you improve mid-corner stability and corner exit speed.
it is a bit counter intuitive as for AX best grip you want to minimize understeer in low-speed corner entry with a softer front sway bar and stiffer rear, but for track setup it becomes more critical to optimize mid-corner stability with both stiffer sway bars, front and rear, and those bars should be set accurately for both rear and front to tilt as similar rate so you would not loose grip at your heavy *** at mid-corner.
then you deal with understeer of front axle at corner entry by using trailbraking and overall handling of your suspension pre-loading side what needs to have grip and then maitaining this load while you steer to the apex, so it is all about overall balance.
beleive or not, stock car is neutral enough. it just has way to much 'rocking' movement and that is getting eliminated with stiffer sway bars so under load contact patch on your tires not getting moved all the way out to the outer edge of the tire.
install of the front sway bar is a moderately complicated DIY - i got it done at the shop as it requires to unbolt crossmember and, well, it is doable but not very simpe if you have no proper lift in your garage.
rear bar is very simple to replace.
go to tarett.com or give thema call and ask about all existing versions of sway bars for GT3 as there are more than one version and you want to have a matching set.
http://www.tarett.com/items/996-997-...links/list.htm
most of folks there moved to gt3 cars long time ago.i would recommend to spend a bit more and get both matching gt3 bars if you really want to go down that road.
also, it (IMHO) only makes sense if you also already got GT3 LCAs installed and camber level is set to -2deg area (like -2.5f -2r) and you still want to do additional adjustments.
I had only rear gt3 bar installed and i did not quite like how front behaved in the turns. what you achieve with both gt3 bars set to middle is minimization of car tilt in the mid-turn so essentially you do not improve corner entry grip but you improve mid-corner stability and corner exit speed.
it is a bit counter intuitive as for AX best grip you want to minimize understeer in low-speed corner entry with a softer front sway bar and stiffer rear, but for track setup it becomes more critical to optimize mid-corner stability with both stiffer sway bars, front and rear, and those bars should be set accurately for both rear and front to tilt as similar rate so you would not loose grip at your heavy *** at mid-corner.
then you deal with understeer of front axle at corner entry by using trailbraking and overall handling of your suspension pre-loading side what needs to have grip and then maitaining this load while you steer to the apex, so it is all about overall balance.
beleive or not, stock car is neutral enough. it just has way to much 'rocking' movement and that is getting eliminated with stiffer sway bars so under load contact patch on your tires not getting moved all the way out to the outer edge of the tire.
install of the front sway bar is a moderately complicated DIY - i got it done at the shop as it requires to unbolt crossmember and, well, it is doable but not very simpe if you have no proper lift in your garage.
rear bar is very simple to replace.
go to tarett.com or give thema call and ask about all existing versions of sway bars for GT3 as there are more than one version and you want to have a matching set.
http://www.tarett.com/items/996-997-...links/list.htm
I was thinking just rear to begin with due to ease of installation.
For me on the road the understeer I can deal with, but on track it really does simply push to much, I've played with pressures, done driver training etc. and simple fact is the car is too biased towards understeer even after a GEO.
I am planning on getting the 997.2 GT3 rear bar which is 25.5mm thick, would this on its softest setting still be stiffer than the stock bar do you know?
I my contemplate adding the front bar along with LCA's at a later date when I can get my car to the shop, but for now the rear bar is a quick and possible solution to my understeer, especially on track.
07-23-2012, 03:34 PM
#64
Rennlist Member
I was thinking just rear to begin with due to ease of installation.
For me on the road the understeer I can deal with, but on track it really does simply push to much, I've played with pressures, done driver training etc. and simple fact is the car is too biased towards understeer even after a GEO.
I am planning on getting the 997.2 GT3 rear bar which is 25.5mm thick, would this on its softest setting still be stiffer than the stock bar do you know?
I my contemplate adding the front bar along with LCA's at a later date when I can get my car to the shop, but for now the rear bar is a quick and possible solution to my understeer, especially on track.
For me on the road the understeer I can deal with, but on track it really does simply push to much, I've played with pressures, done driver training etc. and simple fact is the car is too biased towards understeer even after a GEO.
I am planning on getting the 997.2 GT3 rear bar which is 25.5mm thick, would this on its softest setting still be stiffer than the stock bar do you know?
I my contemplate adding the front bar along with LCA's at a later date when I can get my car to the shop, but for now the rear bar is a quick and possible solution to my understeer, especially on track.
with street parts you are most likely with more camber in rear than in front - like -1 deg front -1.5 deg rear, as with stock parts -1 or -1.2 deg is the max negative camber you may have in front while rear with toe-0.10 is limited by -19deg or so. so it is common to set more in rear to improve overall grip while car understeers like crazy due to this.
when you go from -1/-1.5 into -2.5/-2 car behaves and handles totally different in corners. after that change you will get a negative effect from having stiffer rear bar compared to soft front.
so my advice would be to be consistent in rebuilds of suspension. to do front LCAs and front bar at same time is the right approach. put on tarett rear toe arms at same time.
if you want to drop car all the way low for track - buy tarett front tie rods with bump steer and rear toe arms with bump steer.
they do cost a lot but will allow to lower down car a lot too. without them you`ll have to remain may be only an inch or so lower from stock ride height.
http://www.tarett.com/items/996-997-...-arms/list.htm
Last edited by utkinpol; 07-23-2012 at 04:27 PM.
07-23-2012, 05:04 PM
#65
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Hi m8
So are you saying putting the rear bar in will help now but when I put in lower LCA's and get upto -2.5 camber it would make things actually worse?
My plan was to fit rear bar, try it on softest and medium setting. Do a track event.
Then to fit lower LCA's, front bar and re-do the GEO aiming for about -2.3 negative on the front if possible.
Would this be an OK approach?
Just right now the car pushes way too much and the stock front bar is pretty thick anyway, hence why it pushes on so much. So I just thought a thicker rear bar would help to shift the balance a bit more.
Then at a later date I can add the LCA's, front bar and GEO and the car should then be the ideal mix for road and track.
So are you saying putting the rear bar in will help now but when I put in lower LCA's and get upto -2.5 camber it would make things actually worse?
My plan was to fit rear bar, try it on softest and medium setting. Do a track event.
Then to fit lower LCA's, front bar and re-do the GEO aiming for about -2.3 negative on the front if possible.
Would this be an OK approach?
Just right now the car pushes way too much and the stock front bar is pretty thick anyway, hence why it pushes on so much. So I just thought a thicker rear bar would help to shift the balance a bit more.
Then at a later date I can add the LCA's, front bar and GEO and the car should then be the ideal mix for road and track.
