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991.2 GT3 track alignment

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Old 12-26-2017, 08:56 PM
  #16
Mr. Turtles
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The community is not ignoring you Palting, there is actually a very similar thread already that has been answered

https://rennlist.com/forums/991-gt3-...nment-rwd.html

And as per Orthojoe's recent comments on the 991.2 go slowly. Too many changes too fast can mess everything up with no gains. My personal experience with the 991S was that some camber around 2 in front and a little more in the back helped my tires to wear evenly.

https://rennlist.com/forums/991-gt3-...s-awesome.html
(entry 23)
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Old 12-26-2017, 09:37 PM
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Thanks. Subscribed to orthojoes new thread. Man, my car better get here soon, I'm already subscribed to a dozen threads just because I'm getting too antsy! Only three more months, but it seems like forever.
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Old 12-26-2017, 10:36 PM
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Here is what I believe to be true
1) For whatever reason, alignment changes from stock on the 991 GT3 and 981 GT4 DO NOT improve the performance of the car. Some changes could actually make the car perform worse.

2) In the past I would constantly be chasing for the right alignment to give me even tire wear and longer lasting tires. I was never able to find a setup that yielded in tires that lasted longer.

This is what I would do, regardless of what your skill level is and is what I plan to do.

1) Drive the car with bone stock alignment and dial out any characteristics you don’t like via the sway bars and see how long the tires last this way

2) Dial in max amount of camber up front before front caster gets to be too great and causes rubbing in the fender liner. I’m predicting you can probably get about -2.5 camber before the front caster turns into a problem. Dial in the rear to be about 0.3 less camber than the front (-2.2). Set the rear total toe in at 6mm, the front total toe out at 3mm. See what you think of the car then and see how many days you get out the tires.

3) Report back to me/us so I can just do one of the above and save some time and money. LOL




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Old 12-27-2017, 01:24 AM
  #19
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Originally Posted by orthojoe View Post
Here is what I believe to be true
1) For whatever reason, alignment changes from stock on the 991 GT3 and 981 GT4 DO NOT improve the performance of the car. Some changes could actually make the car perform worse.

2) In the past I would constantly be chasing for the right alignment to give me even tire wear and longer lasting tires. I was never able to find a setup that yielded in tires that lasted longer.

This is what I would do, regardless of what your skill level is and is what I plan to do.

1) Drive the car with bone stock alignment and dial out any characteristics you donít like via the sway bars and see how long the tires last this way

2) Dial in max amount of camber up front before front caster gets to be too great and causes rubbing in the fender liner. Iím predicting you can probably get about -2.5 camber before the front caster turns into a problem. Dial in the rear to be about 0.3 less camber than the front (-2.2). Set the rear total toe in at 6mm, the front total toe out at 3mm. See what you think of the car then and see how many days you get out the tires.

3) Report back to me/us so I can just do one of the above and save some time and money. LOL
Pardon my ignorance, what kind of caster problem will you run into if you have too much front camber?
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Old 12-27-2017, 01:29 AM
  #20
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The front tires may rub inside. This depends in part on how much camber, how wide the tires are and offset of rims.
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Old 12-27-2017, 01:31 AM
  #21
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Originally Posted by Palting View Post
Thanks. Subscribed to orthojoes new thread. Man, my car better get here soon, I'm already subscribed to a dozen threads just because I'm getting too antsy! Only three more months, but it seems like forever.

Not sure whatís worse - I have my new car but Iím surrounded by snow for hundreds of miles.
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Old 12-27-2017, 02:12 AM
  #22
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Originally Posted by Wind911
Pardon my ignorance, what kind of caster problem will you run into if you have too much front camber?
Adding front camber via the lower control arm shims also adds caster. If you look at cars that have aggressive camber but aren't running adjustable thrust arm bushings the wheel is pushed way forward in the well and no longer centered. In my .1 when I had -2.7 up front the tire ended up rubbing a hole in the fender liner. You need adjustable thrust arm bushings to dial back the caster. I'm not going to deal with that this time around. Stock components only.
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Old 12-27-2017, 02:32 AM
  #23
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Originally Posted by orthojoe View Post
Adding front camber via the lower control arm shims also adds caster. If you look at cars that have aggressive camber but aren't running adjustable thrust arm bushings the wheel is pushed way forward in the well and no longer centered. In my .1 when I had -2.7 up front the tire ended up rubbing a hole in the fender liner. You need adjustable thrust arm bushings to dial back the caster. I'm not going to deal with that this time around. Stock components only.
Thanks for the explanation that's what i suspected. On my 996-3 I run -3.2 front camber via shims and the tire will always grind off the middle pins that holds the liner. Other than that it's fine so I leave it alone.
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Old 12-27-2017, 02:52 AM
  #24
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Originally Posted by orthojoe View Post
Here is what I believe to be true
1) For whatever reason, alignment changes from stock on the 991 GT3 and 981 GT4 DO NOT improve the performance of the car. Some changes could actually make the car perform worse.

2) In the past I would constantly be chasing for the right alignment to give me even tire wear and longer lasting tires. I was never able to find a setup that yielded in tires that lasted longer.

This is what I would do, regardless of what your skill level is and is what I plan to do.

1) Drive the car with bone stock alignment and dial out any characteristics you donít like via the sway bars and see how long the tires last this way

2) Dial in max amount of camber up front before front caster gets to be too great and causes rubbing in the fender liner. Iím predicting you can probably get about -2.5 camber before the front caster turns into a problem. Dial in the rear to be about 0.3 less camber than the front (-2.2). Set the rear total toe in at 6mm, the front total toe out at 3mm. See what you think of the car then and see how many days you get out the tires.

3) Report back to me/us so I can just do one of the above and save some time and money. LOL




I am planning similar but will run a little more camber front and rear due to higher speed track conditions. The other thing I noted is that my .1 did not like much toe-in rear, if any at all. The car would push and liked to load up the rear too much. I plan to run a neutral rear toe setting to let the car rotate faster and slight toe-out front.

Quite honestly - I think alignment has a lot to do with the driving style of the user. I like a car that is fairly loose and rotates quickly.

I will report back as I plan to align it next week and taking it to COTA end of January.

Going to laugh as I suspect I will be not far off my cup car times due to higher speeds attainable on the straights.

- Chris.
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Old 12-27-2017, 11:19 AM
  #25
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I assume the RWS will affect what normally works in the back in terms of toe in?
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Old 12-27-2017, 11:26 AM
  #26
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Originally Posted by orthojoe View Post
Adding front camber via the lower control arm shims also adds caster. If you look at cars that have aggressive camber but aren't running adjustable thrust arm bushings the wheel is pushed way forward in the well and no longer centered. In my .1 when I had -2.7 up front the tire ended up rubbing a hole in the fender liner. You need adjustable thrust arm bushings to dial back the caster. I'm not going to deal with that this time around. Stock components only.

Orthojoe, first of all thanks for your many great posts on the 991.1 and now the 991.2, they have been very informative. I was told by a friend running a 991.1 GT3 that I need to use caster pucks (to keep wheel at stock caster and avoid any rubbing) after I install 19inch - 265's up front and about 2.5 camber (also likely some shims to get to 2.5). Based on your recent comments were there any major concerns that you ran into with just these changes?
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Old 12-27-2017, 11:31 AM
  #27
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Your alignment for the track will depend on the tires you use. Also your track and driving style will dictate alignment. What works for one guy might not work for the other guy.

with that said....and I know my 991.2 GTS if different than your 991.2 GT3....I’ve found running Michelin Pilot Sport Cup 2 Tires...same Tires you all get on your GT3 is that -1.5 degrees camber all 4 corners with zero toe front and .14 degree toe in each side in rear ( I have rear steer) is working for me right now. I seem to be getting great tire wear at Sebring.

This alignment is far different than what I ran on my 997 2012 GTS.
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Old 12-27-2017, 12:01 PM
  #28
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Originally Posted by Hams955 View Post
I am planning similar but will run a little more camber front and rear due to higher speed track conditions. The other thing I noted is that my .1 did not like much toe-in rear, if any at all. The car would push and liked to load up the rear too much. I plan to run a neutral rear toe setting to let the car rotate faster and slight toe-out front.

Quite honestly - I think alignment has a lot to do with the driving style of the user. I like a car that is fairly loose and rotates quickly.

I will report back as I plan to align it next week and taking it to COTA end of January.

Going to laugh as I suspect I will be not far off my cup car times due to higher speeds attainable on the straights.

- Chris.
You are totally correct that driving style does affect what a preferred setup will be. Your choice in toe settings certainly reflects that, as I would expect the car to be fairly loose with zero toe in the rear. We should preface any reported setups with lap times and preferred handling characteristics of the car. I like more rear toe in and a stiff front bar because I prefer a rear end that is firmly planted so I can be aggressive with early power out of a corner at the expense of a slight amount of understeer. I think the front toe out helps dial out some of that understeer with better turn in, and I rely on some trail braking too.

Originally Posted by Chris R. View Post
I assume the RWS will affect what normally works in the back in terms of toe in?
I haven't found the setups to change much even with RWS. Although, there might be some affect given that hams955 can run with zero toe in the rear. I've always heard that zero toe in the rear can make a 911 undriveable, but he clearly does well with it and RWS may have something to do with it.

Originally Posted by Mr. Turtles View Post
Orthojoe, first of all thanks for your many great posts on the 991.1 and now the 991.2, they have been very informative. I was told by a friend running a 991.1 GT3 that I need to use caster pucks (to keep wheel at stock caster and avoid any rubbing) after I install 19inch - 265's up front and about 2.5 camber (also likely some shims to get to 2.5). Based on your recent comments were there any major concerns that you ran into with just these changes?
Unfortunately, I don't have any experience with running 265 up front. It does intuitively make sense that a wider tire will have less room/tolerance for excess caster and that you'll have to dial it back in order to prevent fender rubbing. The only way to dial it back is with the caster pucks.
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Old 12-27-2017, 12:05 PM
  #29
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Originally Posted by mdrums View Post
Your alignment for the track will depend on the tires you use. Also your track and driving style will dictate alignment. What works for one guy might not work for the other guy.

with that said....and I know my 991.2 GTS if different than your 991.2 GT3....Iíve found running Michelin Pilot Sport Cup 2 Tires...same Tires you all get on your GT3 is that -1.5 degrees camber all 4 corners with zero toe front and .14 degree toe in each side in rear ( I have rear steer) is working for me right now. I seem to be getting great tire wear at Sebring.

This alignment is far different than what I ran on my 997 2012 GTS.
Are you running less camber on your .2GTS compared to your 997GTS? If so, that falls in line with I believe, in that the newer cars don't need as much negative camber
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Old 12-28-2017, 12:11 PM
  #30
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Originally Posted by orthojoe View Post
Are you running less camber on your .2GTS compared to your 997GTS? If so, that falls in line with I believe, in that the newer cars don't need as much negative camber
Yes Joe...exactly...991.2 GTS running less camber than my 997.2GTS. I ran -2.5 front and -2 rear on 997.2 GTS on Nitto NT01 tires. I wish Nitto NT01's came in stock 20" sizes so I could direct compare but it seems like the overall 991 platform requires less camber than the 997 platform. You think so too?
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