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2011 GS Alignment Issue/Question

OldCorvetteFan

Well-known member
Joined
Jul 3, 2005
Messages
117
Location
Northwest Illinois
Corvette
Black 95 6 spd Coupe (Sold); 2011 GS
I bought the car in April, and the selling dealer installed new Michelin Super Sports on it.


I drove it from Dallas, TX to Northwest Illinois, so I put some 1100 miles on it. I've put another four or five hundred miles on it since I bought it.


After reading all the horror stories of worn out tires, I decided that getting an alignment sooner was better than later. There didn't seem to be any issues with the car with respect to handling, response, wandering, or anything else.


My local dealer has done pretty good work for me in the past, and I had a 20% off coupon that I needed to use, so I thought I'd give them a try.


I'd seen the recommendations for the Pfadt alignment, and took a copy of that with me when I spoke with the Service department. I told them that I didn't have any issues with the car, and I primarily wanted the alignment as a precaution, and that I was looking to balance tire life and good street handling (I have no plans to track the car).


When I picked the car up, the tech mentioned that he had some trouble setting the caster that I desired, but in my desire to get to the car, I failed to think through what he was saying, and I also failed to get a copy of the before and after settings.


Unfortunately, on my way home, I noticed that the car was now showing a strong tendency to drift right. I checked at various speeds and various roads, and they all resulted in the same behavior: release the wheel, and the car immediately starts drifting right.


I didn't drive the car over the weekend, and returned it to them Monday morning, describing what I'd observed. A few hours later, I got a call from them saying that the car was ready, the rightward drift was solved, and that the tech had set the car up to minimize tire wear.


So this time I remembered to get the before and after printouts, and it's clear that the tech didn't understand the Pfadt alignment specifications. Sadly, the car STILL has a tendency toward drifting to the right. Rather than taking the car back for a third time, I'm now trying to locate a good alignment shop in this area:


Dubuque, IA
Madison, WI
Rockford, IL
Sterling, IL


If you have a recommendation, please let me know.


Here is the data from the BEFORE and AFTER printout, along with the factory specifications that the dealer used:


Note: The BEFORE settings are what the Technician set it to originally. I don't know what they were when I bought the car (yes, I feel stupid).


FRONT CAMBER:
Factory Range: -1.6° to -0.4°
Pfadt Recommendation: -0.9° to -0.7°
Before: -1.0°(L), -0.7°(R)
After: -1.1°(L), -0.9°(R)
Cross Camber: -0.3°(Before), -0.1°(After)
Factory Specified Cross Camber Range: -0.6° to 0.6°


FRONT CASTER
Factory Range: 7.0° to 8.2°
Pfadt Recommendation: 7.5° to 8.5°
Before: 7.6° (L), 5.9°(R)
After: 7.4°(L), 8.1°(R)
Cross Caster: 1.7°(Before), -0.7°(After)
Specified Cross Caster Range: -0.6° to 0.6°


FRONT TOE:
Factory Range: -0.05° to 0.15°
Pfadt Recommendation: -0.17° to 0.0° (TOTAL Toe)
Before: -0.15°(L), -0.15°(R)
After: 0.04°(L), 0.08°(R)
Total Toe: -0.29°(Before), 0.12°(After)
Specified Total Toe: -0.10° to 0.30°


SAI (Left): 17.7°(Before), 17.4°(After)
SAI (Right): 9.1°(Before), 9.5°(After)


REAR CAMBER:
Factory Range: -1.8° to -0.6°
Pfadt Recommendation: -0.4° to -0.6°
Before: -0.5°(L), -0.6°(R)
After: 0.0°(L and R)
Cross Camber: 0.1° (Before), 0.0°(After)


REAR TOE:
Factory Range: -0.10° to 0.10°
Pfadt Recommendation: -0.17° to 0.0° (TOTAL Toe)
Before: -0.13°(L), -0.21°(R)
After: -0.01°(L), 0.02°(R)
Total Toe: -0.34°(Before), 0.01°(After)
Total Toe Specification: -0.20° to 0.20°


Thrust Angle: 0.04°(Before), -0.02°(After)




So I think it's clear that the Tech missed the Pfadt Toe specification, and read it as each side rather than total.


But what's up with the SAI? I thought those numbers were supposed to be very close between left and right (within a degree or so), and that >1 degree means that something is bent or broken.


Furthermore, there are still several settings that fall OUTSIDE the factory specifications!


I'd also like to know how close some of these readings need to be - for example, if all other readings were OK, does a cross camber actual reading of -0.1° mean that you're close enough?


I would appreciate any detailed explanation of these measurements, and if anyone can provide a recommended shop for me, I would be very grateful.


Thanks,
Steven
 

catbert

Moderator
Joined
Aug 26, 2004
Messages
3,487
Location
Tobacco Road, NC
I used the modified alignment specs Pfadt on my oem Goodyears and they showed 11% wear at 5,500 miles then I took them off (because they are terrible) . I replaced the tires with Michelin Pilot Sports and they show about 10% wear after the next 5,500 miles. The wear is even across the tire, and the car tracks true.

The setting aren't rocket science, and the local Firestone store had no trouble with aligning to the new specs. BTW the car is a 2012 Grand Sport.
 

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