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991.2 GT3 track alignment

Old 12-28-2017, 11:16 AM
  #31  
orthojoe
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Originally Posted by mdrums
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?
Yes. That seems to be the case, which is why I'm going to just run with stock alignment first and see how it goes
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Old 12-28-2017, 02:43 PM
  #32  
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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 should heed this advice.
Made changes to the .2 based on similar alignment done on .1 and before I ever drove the car. What I notice now on the .2 that never felt on .1 is what feels like wandering during street driving. Does not feel as planted as .1. Can't determine if it is the driving characteristic of the Dunlop's (first time I've driven on this brand) or the track alignment or the fact that I lowered (uh, oh, hear a lesson coming...) the car as well - anywhere from 5/16' to 7/16".

Below is what the car is currently set to vs how it arrived (before) and the specified range from Porsche tech manual.
Front Left = -2.3, before -1.7. Specified range = -1.6 -1.5
Front Right = -2.3, before -1.9. Specified range = -1.6 -1.5
Rear Left = -2.0, before -1.9. Specified range = -1.6 -1.5
Rear Right = -2.0, before -1.8. Specified range = -1.6 -1.5
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Old 12-28-2017, 04:43 PM
  #33  
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Originally Posted by C2Spin View Post
I should heed this advice.
Made changes to the .2 based on similar alignment done on .1 and before I ever drove the car. What I notice now on the .2 that never felt on .1 is what feels like wandering during street driving. Does not feel as planted as .1. Can't determine if it is the driving characteristic of the Dunlop's (first time I've driven on this brand) or the track alignment or the fact that I lowered (uh, oh, hear a lesson coming...) the car as well - anywhere from 5/16' to 7/16".

Below is what the car is currently set to vs how it arrived (before) and the specified range from Porsche tech manual.
Front Left = -2.3, before -1.7. Specified range = -1.6 -1.5
Front Right = -2.3, before -1.9. Specified range = -1.6 -1.5
Rear Left = -2.0, before -1.9. Specified range = -1.6 -1.5
Rear Right = -2.0, before -1.8. Specified range = -1.6 -1.5
Thanks for the numbers. The stock settings do look a little more aggressive than I expected.
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Old 12-28-2017, 05:23 PM
  #34  
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It is likely the caster change from lowering it. What Toe do you have? What caster?
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Old 12-28-2017, 05:55 PM
  #35  
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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.
+1 I'm running a little more camber and toe than stock but not much beyond the upper range of the stock settings. Shop suggested a more aggressive alignment wouldn't make the GT4 any faster and I should adjust my driving style or start with the sway bar settings to suit personal preferences rather than messing with the alignment.
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Old 12-29-2017, 11:33 AM
  #36  
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Originally Posted by MileHigh911 View Post
It is likely the caster change from lowering it. What Toe do you have? What caster?
Caster: Front Left = 10.2*, before was 9.6*. No specified range given by Porsche tech.
Caster: Front Right = 10.1*, before was 9.8*. No specified range given by Porsche tech.
Cross Caster Front: 0.1* was -0.1*. Specified range = -0.3* to 0.3* (not sure what cross caster is, but think it has to do with safety - meaning, when you let go of the wheel the car has a tendency to drift to the right and not into oncoming traffic)
Toe: Front Left = 0.02*, before was -0.05*. Specified range = 0.00* to 0.03*
Toe: Front Right = 0.02*, before was 0.09*. Specified range = 0.00* to 0.03*
Total Toe Front = 0.04*, before was 0.04* (not sure what this measure means). Specified range = 0.00* to 0.07*

Toe Rear Left: 0.16*, before was 0.10*. Specified range = 0.13* to 0.20*
Toe Rear Right: 0.16*, before was 0.09*. Specified range = 0.13* to 0.20*
Total Toe Rear: 0.32*, before was 0.20*. Specified range = 0.27* to 0.40*

Funny how some of the actual delivery ranges were outside of the specified range. NOTE: Specified range was through 2016 GT3, so specified ranges could be different for 2018 GT3.
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Old 12-29-2017, 01:00 PM
  #37  
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Your specs wouldn't necessarily make the car drift around on the roads and feel less planted. It could be that the Dunlops have more of a tendancy to tramline on the road surface than the SC2's. It could also be that lowering your car induced more bump steer. However, I'd be surprised if much bump steer has been induced lowering the car less than an inch per your previous statement.

One might just say that the the car is moving around more and it is not a bad thing - just a change.

Personally speaking, I noticed my car is a little more lively on the road from my .1 but it doesn't really bother me.

- Chris
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Old 12-29-2017, 02:41 PM
  #38  
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Thanks, Chris for that POV. Admittedly, I've only driven the car 110 miles so need a bit more time in the seat and good weather to better evaluate.
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Old 12-29-2017, 09:07 PM
  #39  
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Originally Posted by C2Spin View Post
Caster: Front Left = 10.2*, before was 9.6*. No specified range given by Porsche tech.
Caster: Front Right = 10.1*, before was 9.8*. No specified range given by Porsche tech.
Cross Caster Front: 0.1* was -0.1*. Specified range = -0.3* to 0.3* (not sure what cross caster is, but think it has to do with safety - meaning, when you let go of the wheel the car has a tendency to drift to the right and not into oncoming traffic)
Toe: Front Left = 0.02*, before was -0.05*. Specified range = 0.00* to 0.03*
Toe: Front Right = 0.02*, before was 0.09*. Specified range = 0.00* to 0.03*
Total Toe Front = 0.04*, before was 0.04* (not sure what this measure means). Specified range = 0.00* to 0.07*

Toe Rear Left: 0.16*, before was 0.10*. Specified range = 0.13* to 0.20*
Toe Rear Right: 0.16*, before was 0.09*. Specified range = 0.13* to 0.20*
Total Toe Rear: 0.32*, before was 0.20*. Specified range = 0.27* to 0.40*

Funny how some of the actual delivery ranges were outside of the specified range. NOTE: Specified range was through 2016 GT3, so specified ranges could be different for 2018 GT3.
same happened to me. Had to realign per manual factory specs after delivery


Last edited by mrhamamg; 12-30-2017 at 04:24 AM.
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Old 12-29-2017, 09:14 PM
  #40  
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You do realize that a track alignment will negatively impact the carís handling characteristics driving under normal conditions, right?

if you donít want a car that will wander on the street and wear the tires aggressively you should stick to factory alignment specs.

- Chris.
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Old 12-30-2017, 12:59 AM
  #41  
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Yeah, Chris, that's why I purposely used the phrase "track rats like me" in the first post. The alignments and the cars we are talking about here are meant to be for mostly track use, either to improve performance or to preserve tires for track use, or both, and accept the sacrifice for the occasional street use. For driving the cars the way they were designed, to drive them like you stole them!
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Old 12-30-2017, 01:10 AM
  #42  
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Originally Posted by Palting View Post
Yeah, Chris, that's why I purposely used the phrase "track rats like me" in the first post. The alignments and the cars we are talking about here are meant to be for mostly track use, either to improve performance or to preserve tires for track use, or both, and accept the sacrifice for the occasional street use. For driving the cars the way they were designed, to drive them like you stole them!
Sorry that wasnít directed towards you. It was directed to the post above mine.

Chris.
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Old 12-30-2017, 11:10 AM
  #43  
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Adjustable castor pucks for sure.
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Old 01-12-2018, 11:24 AM
  #44  
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Does anybody have what the factory alignment settings should be? Are they any different than the .1?
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Old 01-12-2018, 12:33 PM
  #45  
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Originally Posted by C2Spin View Post
I should heed this advice.
Made changes to the .2 based on similar alignment done on .1 and before I ever drove the car. What I notice now on the .2 that never felt on .1 is what feels like wandering during street driving. Does not feel as planted as .1. Can't determine if it is the driving characteristic of the Dunlop's (first time I've driven on this brand) or the track alignment or the fact that I lowered (uh, oh, hear a lesson coming...) the car as well - anywhere from 5/16' to 7/16".

Below is what the car is currently set to vs how it arrived (before) and the specified range from Porsche tech manual.
Front Left = -2.3, before -1.7. Specified range = -1.6 -1.5
Front Right = -2.3, before -1.9. Specified range = -1.6 -1.5
Rear Left = -2.0, before -1.9. Specified range = -1.6 -1.5
Rear Right = -2.0, before -1.8. Specified range = -1.6 -1.5
Originally Posted by orthojoe View Post
Does anybody have what the factory alignment settings should be? Are they any different than the .1?
I thought the numbers posted by C2spin are the factory specified alignment setting ranges?
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