Yachting effect and the GT3RS (You are all Basterds)
05-18-2012, 01:08 AM
#20
Nordschleife Master
Oh I double dog dare you to go and post this to the "ladies" on the 991 forum!
Yes, I have a bit of "bounce" at very high speed at the track, but you get used to it... I think.
05-18-2012, 02:48 AM
#21
Three Wheelin'
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I'm just glad this place talks about weekend warrior topics and not bling crap like 21" wheels, LEDs or "street racing." Got enough of that juvenile cheese at trainwreck.com and to be honest I am a little disappointed Champion Motorsport supports that place and not here. Don't know the politics and don't care.
05-18-2012, 07:31 AM
#22
I have 2 comments on the wobble.
1) Rear Engine + RWD platform
- if you are directly coming from a 4wdr or a fwd car with front engine, there for sure is an immediate sensation, small but noticeable, that the front of the car 'feels' lighter and that it could be described as a floating feel
- if you can't feel the difference driving a 4wdr Audi with the engine hanging over the front axle vs a 2wdr gt3 with the engine hanging over the rear axle then?
2) Setup
- I also had this floating feel when I first drove the gt3 - and I drive 4wdr Audis as daily so totally get what you are describing. That said, and as Eduardo from Orbit said, it is also almost entirely in the setup of the car - ie this can be dialed out. It is really quite amazing how sensitive these cars are to small alignment adjustments - especially as your butt gets dialed into the car.
- even as a recent example for me where I made another improvement was the highspeed stuff that Francois mentioned. I run an agressive rear wing - just like the feeling of that at Mosport - well last year I started using the front cup spoiler and on the back straight as the car would get that lighter front feeling it is now completely gone.
- so, setup, especially default from the factory, can be highly optimized camber, caster, toe, ride height to get a much more solid feel - much more. On the highspeed stuff, if it is an aero float, then this also can be improved with ride height and the front aero parts - cup lip and dive planes.
- also remember that the car is setup to work and feel good on the street by Porsche - and to be safe from throttle lift oversteer to keep the unprepared from killing themselves. Best part about the gt3/RS is you can with some small adjustments make it work much better on the track.
991 vs 997
- the longer wheelbase of the 991 and all the real effects this creates cannot be replicated in the 997 platform - but the wider front track, once you rotate the struts, shim the control arms for camber/caster, run a 265 front Hoosier on an aftermarket wheel that has a more agressive offset to run the wider tire and to compensate for the strut rotation, then you can set up a gt3 with the same front track as the new 991 - add the setup stuff mention above with aero stuff and the front will be totally planted.
Spring Rates (GT vs non GT cars)
- another thing that you are possibly noticing is the softer rear springs in the non-gt cars. Even in the 997mk1gt3/rs with 'only' a 600# spring, you can get that squating lifting feeling on a throttle stab - the mk2s come with 660#s rears + better front aero so this again 'fixes' this issue. One of the huge improvements I felt, and this surprised me, was when I upped the rear springs and re-valved the shocks for 900# springs. There obviously is a compromise from a street perspective, not nearly as much as you would think, but by 'holding up' the rear of the car with a firmer spring it again gives the front of the car a much more planted feel - this was a revelation to me. I would point out that the Euro tuners (KW Suspension as an example) use 1100# springs on the rear of their Clubsport suspension for 911s and a 450# front - the Ohlin kit that a few have installed use a 1300# rear and 700# front.
Paul
1) Rear Engine + RWD platform
- if you are directly coming from a 4wdr or a fwd car with front engine, there for sure is an immediate sensation, small but noticeable, that the front of the car 'feels' lighter and that it could be described as a floating feel
- if you can't feel the difference driving a 4wdr Audi with the engine hanging over the front axle vs a 2wdr gt3 with the engine hanging over the rear axle then?
2) Setup
- I also had this floating feel when I first drove the gt3 - and I drive 4wdr Audis as daily so totally get what you are describing. That said, and as Eduardo from Orbit said, it is also almost entirely in the setup of the car - ie this can be dialed out. It is really quite amazing how sensitive these cars are to small alignment adjustments - especially as your butt gets dialed into the car.
- even as a recent example for me where I made another improvement was the highspeed stuff that Francois mentioned. I run an agressive rear wing - just like the feeling of that at Mosport - well last year I started using the front cup spoiler and on the back straight as the car would get that lighter front feeling it is now completely gone.
- so, setup, especially default from the factory, can be highly optimized camber, caster, toe, ride height to get a much more solid feel - much more. On the highspeed stuff, if it is an aero float, then this also can be improved with ride height and the front aero parts - cup lip and dive planes.
- also remember that the car is setup to work and feel good on the street by Porsche - and to be safe from throttle lift oversteer to keep the unprepared from killing themselves. Best part about the gt3/RS is you can with some small adjustments make it work much better on the track.
991 vs 997
- the longer wheelbase of the 991 and all the real effects this creates cannot be replicated in the 997 platform - but the wider front track, once you rotate the struts, shim the control arms for camber/caster, run a 265 front Hoosier on an aftermarket wheel that has a more agressive offset to run the wider tire and to compensate for the strut rotation, then you can set up a gt3 with the same front track as the new 991 - add the setup stuff mention above with aero stuff and the front will be totally planted.
Spring Rates (GT vs non GT cars)
- another thing that you are possibly noticing is the softer rear springs in the non-gt cars. Even in the 997mk1gt3/rs with 'only' a 600# spring, you can get that squating lifting feeling on a throttle stab - the mk2s come with 660#s rears + better front aero so this again 'fixes' this issue. One of the huge improvements I felt, and this surprised me, was when I upped the rear springs and re-valved the shocks for 900# springs. There obviously is a compromise from a street perspective, not nearly as much as you would think, but by 'holding up' the rear of the car with a firmer spring it again gives the front of the car a much more planted feel - this was a revelation to me. I would point out that the Euro tuners (KW Suspension as an example) use 1100# springs on the rear of their Clubsport suspension for 911s and a 450# front - the Ohlin kit that a few have installed use a 1300# rear and 700# front.
Paul
Last edited by 997gt3north; 05-18-2012 at 09:19 AM.
05-18-2012, 10:26 AM
#23
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I'm just glad this place talks about weekend warrior topics and not bling crap like 21" wheels, LEDs or "street racing." Got enough of that juvenile cheese at trainwreck.com and to be honest I am a little disappointed Champion Motorsport supports that place and not here. Don't know the politics and don't care.
couldnt have said it better myself!
05-18-2012, 11:41 AM
#26
Nordschleife Master
- even as a recent example for me where I made another improvement was the highspeed stuff that Francois mentioned. I run an agressive rear wing - just like the feeling of that at Mosport - well last year I started using the front cup spoiler and on the back straight as the car would get that lighter front feeling it is now completely gone.
Paul
Paul
Over the winter, I blocked off the radiator exhausts on the bottom, aft of the splitter (rad was already tilted and front bumper had the holes on top) in the quest for more front end "plantedness".
Have done 6 days at Mosport this year, and am happy to report that the car has settled down. Could be in my head, but it's more comfortable. YMMV.
05-18-2012, 11:41 AM
#27
Burning Brakes
Thread Starter
@997gt3north great info, wasn't sure if setup could really help it in that manner, glad it does. I was keeping my fingers crossed that the softer spring rates would be a major factor. I previously owned an RS4 and similar behavior in reverse, heavy braking from a high speed straight into tight turns caused the front to dive and the rear end to get unstable. I have been adverse to swapping out the supension, thus why I like an adjustable one from the factory. Looks like I'll have to get handy with a spanner!!
