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I'm trying to get my C7 Z51's alignment checked and I haven't yet found a shop near Dallas, TX that can confirm they can measure rear caster (using the GM tool that is - CH-47960-10). Most places I call just say they check all angles - toe/camber/caster. But when they say caster they usually only mean front caster. My 2015 C7 has always drifted slightly (even after an alignment) and I have yet to have the rear caster checked so I'm thinking that has to be the problem.
TLDR; Anyone know of any shops in the DFW area that can measure and set rear caster?
Negative caster certainly could be a cause for drifting. Positive caster tends to straighten the wheel when the vehicle is traveling forward, and thus is used to enhance straight-line stability.
The mechanism that causes this tendency can be seen in the castering front wheels of a shopping cart. The steering axis of a shopping cart wheel is set forward of where the wheel contacts the ground. As the cart is pushed forward, the steering axis pulls the wheel along, and since the wheel drags along the ground, it falls directly in line behind the steering axis.
Performance shops such as DSC Sport recommend positive caster of 6.5-7 degrees in the front and 0.7 degrees in the rear. The factory does not do a precise alignment, and the alignments of new cars out of BG vary quite a bit. My car drifted a bit until I had a very precise alignment done at DSC Sport, using the specs above. It is now arrow straight and stable.
There are a number of shops local to DFW very capable.
- G Speed located at Motorsport Ranch in Cresson and;
- RAC Performance in Carrollton - talk to Hans.
These are BY FAR not the only two capable shops in the DFW area, I'm just providing two that I personally know do good work.
VERY IMPORTANT - Make sure you take the alignment sheet posted in this thread and tell them EXACTLY what you want all the settings and get a printout having the tech write on the sheet the rear caster..
I'm trying to get my C7 Z51's alignment checked and I haven't yet found a shop near Dallas, TX that can confirm they can measure rear caster (using the GM tool that is - CH-47960-10). Most places I call just say they check all angles - toe/camber/caster. But when they say caster they usually only mean front caster. My 2015 C7 has always drifted slightly (even after an alignment) and I have yet to have the rear caster checked so I'm thinking that has to be the problem.
TLDR; Anyone know of any shops in the DFW area that can measure and set rear caster?
OK cool, thanks for the spec sheet! And I have heard good things about RAC so I will probably go there. Given that RAC isn't a GM facility, can they still measure rear caster on a C7? They probably can just using one of the tools for the Porsches I guess. Although I can probably just do what rikhek said and confirm that they write down the rear caster angle to make sure something was actually changed.
The tool, CH47960-10 is C7 specific. It is a little fixture that fits into two hole in the rear knuckle. If they do track alignments on C7 they probably have one.
There are a number of shops local to DFW very capable.
- G Speed located at Motorsport Ranch in Cresson and;
- RAC Performance in Carrollton - talk to Hans.
These are BY FAR not the only two capable shops in the DFW area, I'm just providing two that I personally know do good work.
VERY IMPORTANT - Make sure you take the alignment sheet posted in this thread and tell them EXACTLY what you want all the settings and get a printout having the tech write on the sheet the rear caster..
Rick
RAC-been using them for years. I cannot imagine there's anything unique as far as a C7 alignment goes.
RAC-been using them for years. I cannot imagine there's anything unique as far as a C7 alignment goes.
Yes, C7 requires an adapter ($180) that establishes the vertical axis through the ball joints for the gauge to be attached to. GM specifies a specific gauge that makes it easier to do the job but a saw blade angle gauge with 0.1 degree accuracy will work. You can get one in the mid $30s.
Some people have said to use a couple of steel pins stuck in the reference holes in the knuckle but you need a gauge long enough to go across both pins.
Do not assume any shop can set the rear caster. There are only 3 GM cars that have adjustable rear caster and two are out production. There are only a couple other brands that have adjustable rear caster and I imagine each require a special tool to adapt a gauge to the axis through the ball joints. The method used to establish front caster can't be used because the rear wheels can't be moved through a 30 degree arc from side to side.
Ask any shop what tools they will use to set rear caster. A lot will tell you it can't be done as it isn't something the mechanics have heard of.
When done you want them to write the rear caster settings on the alignment sheet. Both before and after readings.
I would also recommend Texas Track Works in Fort Worth, they do a really good job.
Got an appointment on Tuesday. So far, sounds like a great team from just a phone call. gave me a bunch of hints and truly sounded like they do good work! Can't wait.
I used TTW once, when they were still going by their original name, and left, lets just say, less than impressed. I wish you the best of luck and hopefully have a much better experience than I did. With that C7-specific tool, you might be better off checking with the big dealerships such as Classic and Huffines. I've been happy with my alignments from Huffines in Lewisville, but I have no idea if they have that tool or not.
I used TTW once, when they were still going by their original name, and left, lets just say, less than impressed. I wish you the best of luck and hopefully have a much better experience than I did. With that C7-specific tool, you might be better off checking with the big dealerships such as Classic and Huffines. I've been happy with my alignments from Huffines in Lewisville, but I have no idea if they have that tool or not.
I'm one to watch closely. Thanks for the feedback.
I used TTW once, when they were still going by their original name, and left, lets just say, less than impressed. I wish you the best of luck and hopefully have a much better experience than I did. With that C7-specific tool, you might be better off checking with the big dealerships such as Classic and Huffines. I've been happy with my alignments from Huffines in Lewisville, but I have no idea if they have that tool or not.
Well you were correct to a certain extent. I was not impressed. I was told over the phone that they had the corvette specific tool, even after I asked if he was sure. While aligning the car, I asked about it and the guy said he did not have the tool and that he would give me 50% off for the misinformation. The aligner also had trouble getting the rear camber negative enough without throwing out the toe, however the rear of my car is raised all the way due to tire rub with 285/35R20 ratio tires and I attribute some of it to that. I also mentioned about removing the washers but he said it most likely wouldn't do anything. Once I get proper fitting tires and lower it again, I'll get it rechecked. I'll look into a place that can do a proper caster check in the fall. Here are the before/after, still better than it was but like I said, not impressed:
Last edited by BrunoTheMellow; 06-20-2017 at 01:42 PM.
01-26-2017, 01:33 PM
Alignment shops in DFW area - rear caster?
