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I've read almost all of them. My frustration was the inability to come out with some actual values to give the alignment tech. There was a thread where @Bill Dearborn did provide the stock specs with a suggested adjustment to minimize tire wear. I believe I have captured the numbers in the attached image. I was going to add the DSC specs to my table, but they use mm and not degrees, making the comparison useless. A couple of thoughts:
Per Bill, the factory specs aren't really that aggressive. We do often see owners who are surprised to see their tires worn to the chord at approx 10K miles. Do you guys think that's just how it is, or were those cars an anomaly, and they came from the factory with a bad alignment?
If those examples are an anomaly, I'm thinking I'll just go with the factory specs (with a much tighter +/-). With the ridiculously low amount of miles I put on my car, maybe it won't be a problem.
Goals: I do like to carve up the twisty backroads, although I don't plan to track my car. I do plan to ask the locals who they recommend for C7 alignment, along with the rear caster requirement.
What is a reasonable (+/-) to ask the tech to achieve?
From: 2007 Nat'l Corvette Challenge 11.50 index Champ. New Jersey
Originally Posted by need-for-speed
I've read almost all of them. My frustration was the inability to come out with some actual values to give the alignment tech. There was a thread where @Bill Dearborn did provide the stock specs with a suggested adjustment to minimize tire wear. I believe I have captured the numbers in the attached image. I was going to add the DSC specs to my table, but they use mm and not degrees, making the comparison useless. A couple of thoughts:
Per Bill, the factory specs aren't really that aggressive. We do often see owners who are surprised to see their tires worn to the chord at approx 10K miles. Do you guys think that's just how it is, or were those cars an anomaly, and they came from the factory with a bad alignment?
If those examples are an anomaly, I'm thinking I'll just go with the factory specs (with a much tighter +/-). With the ridiculously low amount of miles I put on my car, maybe it won't be a problem.
Goals: I do like to carve up the twisty backroads, although I don't plan to track my car. I do plan to ask the locals who they recommend for C7 alignment, along with the rear caster requirement.
What is a reasonable (+/-) to ask the tech to achieve?
I'm not sure why the right & left sides would not be equal or as close to equal as possible?
Toe should be measured in in, 0.05 in rather than degrees. Run a small amount of toe out on the front to help turn in on track (80/20 split use). If only driving on street, 0 out the toe and minimize camber (-1.2 is what I run, and is still very conservative, a street camber setting)
I've heard of running differing camber per side to deal with the crowning of the roads, personally I've had all street settings on 2 of my vettes and never thought of trying to account for crowning. Tire wear and street feel felt great to me.
I'm not sure why the right & left sides would not be equal or as close to equal as possible?
Ron
I believe that is GM's compensation for the road crown. With front camber being equal the car would pull to the right when riding to the right side of the road crown and to the left when riding on the left side of the crown. Since most travel is on the right side of the crown they can offset the pull by running more negative camber on the right side as a car will pull in the direction of the most positive camber.
Toe should be measured in in, 0.05 in rather than degrees. Run a small amount of toe out on the front to help turn in on track (80/20 split use). If only driving on street, 0 out the toe and minimize camber (-1.2 is what I run, and is still very conservative, a street camber setting)
I've heard of running differing camber per side to deal with the crowning of the roads, personally I've had all street settings on 2 of my vettes and never thought of trying to account for crowning. Tire wear and street feel felt great to me.
Originally Posted by need-for-speed
Thanks Slade. This document states degrees for toe?
The reason toe is measured in degrees is because it is the most accurate way of measuring toe. When using distance measurements such as mm or fractions of inches the measurement changes with the diameter of the wheel. A 1/32 toe setting on a 20 inch wheel doesn't provide the same angle as a 1/32 setting does on a 16 inch wheel. When measuring the toe angle of a wheel using degrees it doesn't matter whether the wheel has a diameter of 1 foot or 20 ft. The angle will always be the same number of degrees.
I know it is hard to measure degrees if you don't have an alignment machine, however, there are conversion formulas and charts that let you convert between the two methods of measurement. For example:
A key item to remember is wheel diameter is actually the two points where you make your measurement. If that is on the edge of the rim or outside of the tire diameter. When using a string method to measure toe most of the time you will be measuring to the wheel edge. However, if you are using toe plates with tape measures stretched between them you now have a wider distance (maybe 24 inches) between the two measurement points and you need to recalculate for that change.
Bill
Last edited by Bill Dearborn; Jul 14, 2022 at 04:35 PM.
Thanks Bill. That makes sense. Leave it to GM to spec it in degrees
I Shop in Northwest Houston that is recommended by the local Corvette guys. Sals Auto Sport. I talked to him on the phone and he sounds very competent and interested in getting the alignment as accurate as possible. He brought up rear caster on C7s before I did. He also mentioned the crappy tolerances that are considered acceptable (turns the image on the machine for a particular corner green ) versus getting both sides the same which is what I want. I’m gonna discuss with him where to set toe, etc. Got an appointment for Thursday.
After that, I gotta put 1,000 mile on her ASAP for my GMEPP.
I have never bought the "road crown" argument for different alignments left and right. If you spend any amount of time on the freeway, then the car will pull to the left in the center and left lanes, using that rationale. I set my wheels identical left and right for street use. I also do not allow +/- on my settings. I pick a number and make certain my wheels are at that number. A +/- variance just allows for laziness.
If you run on a short track that goes around a circuit to the left, then that may be a reason to favor left turns, so a bit more camber and castor on the right.
Yeah, this guy charges more, but he will spend 2 hours or more getting all the readings right, and the same side to side, including rear caster, as opposed to the wide open tolerances in the specs. He’ll also road force balance the tires for $35 ea if needed.
Here were my final alignment specs that I had done right after I had my Z06 lowered.
So did they have the tools to measure the rear caster and did they set it if they did? The alignment machine can't measure rear caster since the alignment heads aren't fastened to the knuckle under the car.
So did they have the tools to measure the rear caster and did they set it if they did? The alignment machine can't measure rear caster since the alignment heads aren't fastened to the knuckle under the car.
Bill
Yes. Forza here in Phoenix is one of the best and they knew all about the rear caster. Let me be out there with them when they set it and explained what they were doing. Is sad how many people / shops are unaware of this adjustment.
yet another alignment thread
