GT 4 suspension
07-27-2016, 08:10 PM
#1
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GT 4 suspension
I took my GT4 in for its first oil change today 3340 miles and to get an alignment and there is where the surprise was. The tech at our local dealership that works on my car is a Master Tech and an avid PCA member and auto x driver. When he brought the car out for me he also had a surprise. He said my car could not be aligned to factory specs in the rear. The reason is that when he adjusted the rear camber to factory specs he did not have enough adjustment on the rear toe links to attain factory directed toe setting. The only way to get proper toe, especially on the left side was to reduce the rear camber on that side to less than factory specs. NOT GOOD. I have checked with other GT 4 owners and they have had the same issue. The rear toe links are standard 981 tow links and do not have the necessary length adjustment to allow factory toe to be set if the camber is set at factory directed specs. INTERESTING to say the least. some have gone to aftermarket toe links to achieve factory camber specs .. takes you out of the stock class and others have lowered their car and thus been able to achieve factory specs wit factory parts. I am looking forward to the response from PORSCHE to my techs inquiry. A truly great car and I am appreciative of PORSCHE designing and building it for us, but it would be nice to have all the right parts to achieve factory designed specs with the alignment.
07-27-2016, 08:50 PM
#2
I took my GT4 in for its first oil change today 3340 miles and to get an alignment and there is where the surprise was. The tech at our local dealership that works on my car is a Master Tech and an avid PCA member and auto x driver. When he brought the car out for me he also had a surprise. He said my car could not be aligned to factory specs in the rear. The reason is that when he adjusted the rear camber to factory specs he did not have enough adjustment on the rear toe links to attain factory directed toe setting. The only way to get proper toe, especially on the left side was to reduce the rear camber on that side to less than factory specs. NOT GOOD. I have checked with other GT 4 owners and they have had the same issue. The rear toe links are standard 981 tow links and do not have the necessary length adjustment to allow factory toe to be set if the camber is set at factory directed specs. INTERESTING to say the least. some have gone to aftermarket toe links to achieve factory camber specs .. takes you out of the stock class and others have lowered their car and thus been able to achieve factory specs wit factory parts. I am looking forward to the response from PORSCHE to my techs inquiry. A truly great car and I am appreciative of PORSCHE designing and building it for us, but it would be nice to have all the right parts to achieve factory designed specs with the alignment.
No flame, but there are numerous posts (found via search) on this already. Now did you master tech perform a Porsche approved corner balance pre of the alignment. If he did (its covered by warranty) and still had the issue he should've submitted a warranty claim for not being able to get an alignment into spec.
07-27-2016, 09:14 PM
#3
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No flame, but there are numerous posts (found via search) on this already. Now did you master tech perform a Porsche approved corner balance pre of the alignment. If he did (its covered by warranty) and still had the issue he should've submitted a warranty claim for not being able to get an alignment into spec.
07-28-2016, 08:31 AM
#4
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No flame, but there are numerous posts (found via search) on this already. Now did you master tech perform a Porsche approved corner balance pre of the alignment. If he did (its covered by warranty) and still had the issue he should've submitted a warranty claim for not being able to get an alignment into spec.
07-28-2016, 08:51 AM
#5
How far from spec did they get? My alignment sheet shows spec as -1.42 to -1.58 and the most I could get was -1.36. Most of the discussion in this forum is around HPDE and folks have been going to aftermarket rear toe arms. (See the track wiki "sticky" at the top.) I know zip about autocross but would .1 to .2 less neg camber make much of a difference? Still it's disappointing in principle that we can't align to the factory spec without mods.
07-28-2016, 02:03 PM
#6
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How far from spec did they get? My alignment sheet shows spec as -1.42 to -1.58 and the most I could get was -1.36. Most of the discussion in this forum is around HPDE and folks have been going to aftermarket rear toe arms. (See the track wiki "sticky" at the top.) I know zip about autocross but would .1 to .2 less neg camber make much of a difference? Still it's disappointing in principle that we can't align to the factory spec without mods.
07-28-2016, 04:08 PM
#7
If your car is at stock height your master tech did not perform the corner balance under warranty as you hinted at in an earlier post. The Porsche spec allows for adjustment of height which will change the camber setting and therefore will give you more toe adjustability. Tell'em to quit feeding you kool-aid and do their job.
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08-04-2016, 06:41 AM
#8
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A bit of an update. My dealer got word back from PORSCHE that while they were aware of some issues with rear suspension alignment from customer reports, mine seems to be the worst case reported. As a result they have requested that I bring the car to the dealer and a through evaluation will be made of the issue using my car to find a solution. Will miss have the car for up to a week but at the same time I am glad that PORSCHE has once again stepped ' up to the plate" to work a solution. Its a great car just needing a tweak to overcome this small issue
08-06-2016, 08:02 PM
#9
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A bit of an update. My dealer got word back from PORSCHE that while they were aware of some issues with rear suspension alignment from customer reports, mine seems to be the worst case reported. As a result they have requested that I bring the car to the dealer and a through evaluation will be made of the issue using my car to find a solution. Will miss have the car for up to a week but at the same time I am glad that PORSCHE has once again stepped ' up to the plate" to work a solution. Its a great car just needing a tweak to overcome this small issue
https://rennlist.com/forums/gt4/9085...l#post13507883
08-06-2016, 09:40 PM
#11
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The WSM for the GT4 shows 109 mm (+2/-0) front and 130 mm (+2/-0) rear, measured at locations shown in the WSM that I'm sure you are familiar with. The WSM notes says these measurements are to be taken with full fuel tank and fluid reservoirs, but no driver or additional weights.
The service tech today used the same target settings for front/rear height as I find in the WSM, but he typed the tolerance incorrectly where this paperwork shows +/- 2 mm instead of +2/-0.
08-06-2016, 09:55 PM
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The WSM also states for left/right difference and front/rear deviation:
Permitted transverse inclination of the vehicle: Max. difference in height, left to right = 5 mm
Permitted longitudinal inclination of the vehicle: Max. total deviations at front and rear = 10 mm
So if both front and rear height were set at target (109 front, 130 rear) there would be a 21 mm deviation (130-109), violating the max 10 mm deviation. So something needs clarification. The service manager at the Porsche dealership is chasing these specs and WSM language to ground truth before we go any further.
FWIW, while I'm in the WSM reading, I see that the same section of the WSM states the following for corner balance: "Max. wheel-load difference, right to left, on front axle 10 kg and on rear axle 15 kg. Try for max. 5 kg on the front axle and max. 10 kg on the rear axle."
Permitted transverse inclination of the vehicle: Max. difference in height, left to right = 5 mm
Permitted longitudinal inclination of the vehicle: Max. total deviations at front and rear = 10 mm
So if both front and rear height were set at target (109 front, 130 rear) there would be a 21 mm deviation (130-109), violating the max 10 mm deviation. So something needs clarification. The service manager at the Porsche dealership is chasing these specs and WSM language to ground truth before we go any further.
FWIW, while I'm in the WSM reading, I see that the same section of the WSM states the following for corner balance: "Max. wheel-load difference, right to left, on front axle 10 kg and on rear axle 15 kg. Try for max. 5 kg on the front axle and max. 10 kg on the rear axle."
08-06-2016, 10:26 PM
#13
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The WSM also states for left/right difference and front/rear deviation:
Permitted transverse inclination of the vehicle: Max. difference in height, left to right = 5 mm
Permitted longitudinal inclination of the vehicle: Max. total deviations at front and rear = 10 mm
So if both front and rear height were set at target (109 front, 130 rear) there would be a 21 mm deviation (130-109), violating the max 10 mm deviation. So something needs clarification. The service manager at the Porsche dealership is chasing these specs and WSM language to ground truth before we go any further.
FWIW, while I'm in the WSM reading, I see that the same section of the WSM states the following for corner balance: "Max. wheel-load difference, right to left, on front axle 10 kg and on rear axle 15 kg. Try for max. 5 kg on the front axle and max. 10 kg on the rear axle."
Permitted transverse inclination of the vehicle: Max. difference in height, left to right = 5 mm
Permitted longitudinal inclination of the vehicle: Max. total deviations at front and rear = 10 mm
So if both front and rear height were set at target (109 front, 130 rear) there would be a 21 mm deviation (130-109), violating the max 10 mm deviation. So something needs clarification. The service manager at the Porsche dealership is chasing these specs and WSM language to ground truth before we go any further.
FWIW, while I'm in the WSM reading, I see that the same section of the WSM states the following for corner balance: "Max. wheel-load difference, right to left, on front axle 10 kg and on rear axle 15 kg. Try for max. 5 kg on the front axle and max. 10 kg on the rear axle."
Also shouldn't the dealer check and report the measured height for each of the four points.
Each rotation of the strut adjusting nut changes ride height by 1.1 mm with the sway bars disconnected.
08-06-2016, 11:03 PM
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The fuel tank was 1/2 full at the time of measurement. He should have reported all 4, but since at least 1 side front and rear was out of spec, I'm taking the car back for a whole day visit. I had agreed with them before I took the car in today that if ride height was off (as I suspected it was) I would bring the car back early one day and get a loaner car.
08-07-2016, 06:45 PM
#15
just measured my new GT4 with 360 mi and full tank. LF 110.23 RF 110.21 LR 135.00 RR 134.15. The front is 3mm lower than my first GT4 with 1000 mi on it when measured, the rear is the same. Will check again @1000mi.