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Recently installed the LG drop spindles and went in to get an alignment from an independent (well reviewed) shop and asked for the DSC sport settings for street/occasional track use. The owner of the shop fought with me about the settings and kept saying its no good and he would do it differently. I'm not too knowledgeable with suspension set ups so I started to question DSC. Here is what I ended up with, he said the rear toe indicated in the DSC was too much and it would eat tires. He also said his hunter machine isn't able to see rear caster? Thoughts/opinions on what I should do? Is this good to run? Should I got to a dealership? I'm looking for a longer lasting tire route, but I do spend weekends in the canyons.
You need to get the rear caster setup ASAP. There's a special GM tool installed on the knuckle during the alignment to measure it and do the alignment accordingly. Once it's measurable, any alignment shop can do it. I've sourced the tool myself and also have a digital angle cube, so I can theoretically get it aligned anywhere. Your can search for the tool on the forums to find the part number. A forum member is also manufacturing a similar tool for the job for cheaper.
Up to you. I don't use dealers for alignment, myself. Some of the race shops will already have the tool. To be able to get it done at any shop (and actually get it fixed where you got it done), you should source these tools:
Thanks for the links. It’s really annoying that I have to buy a tool so an alignment shop and do a proper alignment! I’d rather just find a shop that is better equipped. Rear caster aside, how does everything else look in the alignment?
Since you're from Socal, you can schedule an appointment with West End alignment in Gardena. They have the rear caster tool to do a proper alignment. Chris did my alignment a few months ago with my DSC controller.
Since you're from Socal, you can schedule an appointment with West End alignment in Gardena. They have the rear caster tool to do a proper alignment. Chris did my alignment a few months ago with my DSC controller.
yeah, he initially installed my lowering bolts but I don’t like his ‘I have to do corner balancing and always charge $350’.
Your front wheel alignment looks pretty good for street driving. The rear not so much... Too much camber in the rear for street driving and best tire life. I would want more like -0.7 to a max of -1.0 rear camber for street only use. You also have too much rear toe in. I would want to see closer to zero toe in the rear.
With these settings the camber will wear the inside edge of the tire and the toe will wear the outside edge of the tire so wear might be balanced, but wear will be higher than it needs to be. Handling will be fine with these settings since you don't rack the car or autocross.
Since he changed the rear caster significantly, I would suspect he threw off the caster since he did not have a way to measure it. Caster will not affect tire wear but it will make the car less stable especially if there is a significant cross caster difference. You should shoot for 0.0 to 0.7 positive rear caster with each side the same.
That's strange, he didn't mention anything about corner balancing to me.
just called him, correction, he only forces the corner balancing when adjusting ride height--since he was lowering my car he then required it.
Originally Posted by RacerRik
Your front wheel alignment looks pretty good for street driving. The rear not so much... Too much camber in the rear for street driving and best tire life. I would want more like -0.7 to a max of -1.0 rear camber for street only use. You also have too much rear toe in. I would want to see closer to zero toe in the rear.
With these settings the camber will wear the inside edge of the tire and the toe will wear the outside edge of the tire so wear might be balanced, but wear will be higher than it needs to be. Handling will be fine with these settings since you don't rack the car or autocross.
Since he changed the rear caster significantly, I would suspect he threw off the caster since he did not have a way to measure it. Caster will not affect tire wear but it will make the car less stable especially if there is a significant cross caster difference. You should shoot for 0.0 to 0.7 positive rear caster with each side the same.
This was following the DSC recommendation. Hard to keep track of who to listen to to be honest. How do you know rear caster was significantly changed?
Because I noted when doing my own alignment that rear caster is three times more sensitive than camber when adjusting the cams. What I mean by that is adjusting one lower control arm cam results in a change to caster angle of three times the amount it changes camber. The likelihood of getting lucky on both sides is really low!
Another problem is that the C7 Corvette shop manual incorrectly sates that one adjustment cam is used for camber and one is used for caster. To set both camber and caster correctly involves a bunch of back and forth adjustments of both lower control arm cams.
As far as recommendations, DSC has experience with racing. If you are racing your car, go with their suggestions. If you do not track or autocross your car, their suggestions are not going to be good for maximizing tire life.
Your guy gave you an alignment that matches the DSC Street/Track Alignment fairly closely. The big difference is with rear toe which I agree may be far too much rear toe. His rear toe settings show ~ 1/32 of toe in on each side.
You received the typical answer when it comes to rear caster. Most specialists and shops no nothing about it. There are only 3 car brands in the US that have ever had adjustable rear caster. The Pontiac Solstice, Saturn Skye and the C7 Corvette. Alignment machines have no ability to measure rear caster as it isn't needed for the vast majority of cars and would require adding an electronic angle gauge that can be fastened to the rear knuckles of the cars. The GM Rear Caster gauge was designed for the Solstice and Skye and plugs directly into holes in their rear knuckles but an adapter has to be used to use the gauge on the C7.
I don't know how your dropped knuckles were made but one thing you have to find out is whether or not they have had holes in the knuckles to be able to attach an adapter or gauge of any type. Without the holes, you more than likely can't have rear caster adjusted on your car.
If you find a shop that has the tools (an adapter which is nothing but a steel bar and a gauge which can be a cheap saw blade angle gauge) and the knuckles have the holes that permit mounting of the adapter then you can have the alignment redone. If I were you I would purchase the two tools needed and go back to the guy who did your alignment and let him set rear caster. The other thing is I would tell him to set it at 0.0 degrees on each side Vs the DSC recommendation. The 0.0 recommendation is what Jim Mero says it should be and he should know since he was the GM test driver that determined what it should be.
Your front wheel alignment looks pretty good for street driving. The rear not so much... Too much camber in the rear for street driving and best tire life. I would want more like -0.7 to a max of -1.0 rear camber for street only use. You also have too much rear toe in. I would want to see closer to zero toe in the rear.
With these settings the camber will wear the inside edge of the tire and the toe will wear the outside edge of the tire so wear might be balanced, but wear will be higher than it needs to be. Handling will be fine with these settings since you don't rack the car or autocross.
Since he changed the rear caster significantly, I would suspect he threw off the caster since he did not have a way to measure it. Caster will not affect tire wear but it will make the car less stable especially if there is a significant cross caster difference. You should shoot for 0.0 to 0.7 positive rear caster with each side the same.
Was just able to look up factory recommendations for alignment for the FE7 for street setup that Bill posted a few weeks ago in another thread, and they want rear camber at -1.1. I would imagine that would be for optimal tire life, no?
Here is more detail specifically related to the OP's data on why I think think the rear caster will be off.
Looking at the right rear suspension, the original camber was at -1.5 deg. The alignment shop adjusted it to -1.2 deg, so that is a 0.3 deg change. If the shop followed the GM C7 Shop manual, they would have adjusted the camber by rotating the rear lower control arm cam. The manual shows the rear cam is used to adjust camber and the front cam is used to adjust caster - this is wrong information, but lets assume the shop followed GM's procedure. Adjusting only the rear cam inward would result in camber changing to +0.3 degrees (to get to the end result of -1.2 deg) and the caster would have changed by +0.9 deg. That is a big change in caster angle when you are looking for only 0.0 to 0.7 deg for proper caster.
Was just able to look up factory recommendations for alignment for the FE7 for street setup that Bill posted a few weeks ago in another thread, and they want rear camber at -1.1. I would imagine that would be for optimal tire life, no?
GM's original camber specs for the C7 were -0.5 deg for both front and rear. They revised that spec for the FE1, FE2, FE3 and FE4 cars to Front left camber of -0.2 deg, front Right camber of -0.5 deg and both rear cambers at -0.5 deg. That sounds ridiculous to me. Makes no more sense that stating the rear adjustment cam sets camber. But these specs are likely designed for maximum tire life.
The GM specs for FE6 and FE7 cars are Front left camber of -0.6 deg, front Right camber of -0.9 deg and both rear cambers at -1.1 deg. These specs are likely to increase performance at the cost of more tire wear for the higher performance variants of the car.
Your guy gave you an alignment that matches the DSC Street/Track Alignment fairly closely. The big difference is with rear toe which I agree may be far too much rear toe. His rear toe settings show ~ 1/32 of toe in on each side.
You received the typical answer when it comes to rear caster. Most specialists and shops no nothing about it. There are only 3 car brands in the US that have ever had adjustable rear caster. The Pontiac Solstice, Saturn Skye and the C7 Corvette. Alignment machines have no ability to measure rear caster as it isn't needed for the vast majority of cars and would require adding an electronic angle gauge that can be fastened to the rear knuckles of the cars. The GM Rear Caster gauge was designed for the Solstice and Skye and plugs directly into holes in their rear knuckles but an adapter has to be used to use the gauge on the C7.
Was just able to look up factory recommendations for alignment for the FE7 for street setup that Bill posted a few weeks ago in another thread, and they want rear camber at -1.1. I would imagine that would be for optimal tire life, no?
Any negative camber will accelerate tread wear. They car was designed to handle very well with those specs which are less aggressive than what a lot of people use.
I make and sell the rear caster tool needed to measure the adjustment. I'm not sure if the lg spindles have the caster holes or if the spacing is the same as oem. If you can confirm that from lg and your interested send me a pm.
On the c7 the rear alignment is a 3 pronged adjustment. Camber caster and toe all effect one another and must all be adjusted together, one moves the other etc.
Here is more detail specifically related to the OP's data on why I think think the rear caster will be off.
Looking at the right rear suspension, the original camber was at -1.5 deg. The alignment shop adjusted it to -1.2 deg, so that is a 0.3 deg change. If the shop followed the GM C7 Shop manual, they would have adjusted the camber by rotating the rear lower control arm cam. The manual shows the rear cam is used to adjust camber and the front cam is used to adjust caster - this is wrong information, but lets assume the shop followed GM's procedure. Adjusting only the rear cam inward would result in camber changing to +0.3 degrees (to get to the end result of -1.2 deg) and the caster would have changed by +0.9 deg. That is a big change in caster angle when you are looking for only 0.0 to 0.7 deg for proper caster.
I was thinking about this a bit more and realized that the the camber correction, if following GMs shop manual, would actually result in -0.9deg shift in caster not a positive shift. That being the case, the resulting caster is very likely to be negative which is really bad.
Feedback requested from the alignment gurus
