Alignment shops in DFW area - rear caster?
#1
Alignment shops in DFW area - 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?
Thanks!
TLDR; Anyone know of any shops in the DFW area that can measure and set rear caster?
Thanks!
#2
Rear caster wouldn't cause that problem. On my '16 Z51 I had positive caster on one side and negative on the other from the factory.
#3
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.
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.
Last edited by Foosh; 01-26-2017 at 02:10 PM.
#4
Safety Car
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
- 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
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pdiddy972 (03-18-2017)
#5
The alignment specs were posted in another thread, but here are the specs Rick is talking about.
Last edited by Foosh; 01-26-2017 at 02:14 PM.
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Yaupon (01-23-2018)
#7
Le Mans Master
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?
Thanks!
TLDR; Anyone know of any shops in the DFW area that can measure and set rear caster?
Thanks!
The following users liked this post:
94LT4 (04-15-2019)
#9
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.
#10
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.
#11
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
- 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
#13
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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.
Bill
#15
#16
#18
Le Mans Master
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.
Last edited by Kracka; 06-15-2017 at 01:51 PM.
#19
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.
#20
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.
Last edited by BrunoTheMellow; 06-20-2017 at 01:42 PM.