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Took my Z06 into one of the larger dealerships in SA today for a track alignment. On the phone service mgr swore they would have no problem adjusting rear caster. I'm looking at this sheet, and I cannot find anything that looks like rear caster. Perhaps I am missing it so let me know your thoughts before I get medieval. Thx.
Typically the alignment machines can't check it so you won't see it on the print out. You need a special bracket and a level. Then they would have to write it down for you someplace.
Odds are they don't even have the tools and therefore can't measure/check rear castor. Went thru the same spiel here.
That's my concern. Despite their "yes, we can do that" answers I'm not seeing evidence that they can. I guess I will have to make an appt with the service manager and discuss what I need from them, and whether or not they can actually deliver what I need.
Odds are they don't even have the tools and therefore can't measure/check rear castor. Went thru the same spiel here.
Odds are high that is true. It is an unusual setting and most shops aren't used to setting it. I only know of two other GM cars that had a rear caster setting/adjustment. They were the Pontiac Solstice and it's sister car the Saturn Sky. The typical attitude would be the owner doesn't understand that caster is only in the front so they say, yes we can do it expecting the Customer to see caster on the sheet and be happy.
OP just go into the service desk with your printout and ask them to show you where the rear caster setting is mentioned. Take a GM document along with you so you can show them there is a rear caster setting. They should be able to find it in the computer but sometimes they don't look very hard.
Bill, etc: Thanks for the feedback. I'm going to do just what you said. Thankfully the rear caster GM document was posted in the master How-Tos.
If they don't have the gauge, I'll ask for a refund and take it to another local dealer that I found in another thread that is known to have the tools to adjust rear caster.
I'm very wary of tracking this car now until I know for certain the rear caster is set correctly. I'm not in the mood for Snap Oversteer
Reading the Master How-To on rear caster today, and looking at the rear end of my car on my lift today, it occurred to me that it might be easy to read the caster angle with an iPhone. The phone has a very sensitive angle gauge within the compass function.
I placed two appropriately sized bolts in the adapter holes noted on the tech bulletin, ensured that my lift ramps were at zero, and then measured the caster angle (see pics). Unless I am crazy, it sure looks like the rear caster is 0 degrees on both sides.
Maybe someone will tell me I'm nuts, but I'd love feedback.
Reading the Master How-To on rear caster today, and looking at the rear end of my car on my lift today, it occurred to me that it might be easy to read the caster angle with an iPhone. The phone has a very sensitive angle gauge within the compass function.
I placed two appropriately sized bolts in the adapter holes noted on the tech bulletin, ensured that my lift ramps were at zero, and then measured the caster angle (see pics). Unless I am crazy, it sure looks like the rear caster is 0 degrees on both sides.
Maybe someone will tell me I'm nuts, but I'd love feedback.
Looks good to me! With just a little more knowledge/effort, you could do your own alignments and even experiment with different settings.
Looks good to me! With just a little more knowledge/effort, you could do your own alignments and even experiment with different settings.
After watching youtube videos all morning, its pretty clear its not rocket science! Anything I can do in my garage is preferable to having someone else do it.
Reading the Master How-To on rear caster today, and looking at the rear end of my car on my lift today, it occurred to me that it might be easy to read the caster angle with an iPhone. The phone has a very sensitive angle gauge within the compass function.
I placed two appropriately sized bolts in the adapter holes noted on the tech bulletin, ensured that my lift ramps were at zero, and then measured the caster angle (see pics). Unless I am crazy, it sure looks like the rear caster is 0 degrees on both sides.
Maybe someone will tell me I'm nuts, but I'd love feedback.
This looks like a really great find. Although the iPhone app appears to have only a 1 degree display resolution, it could still be a valuable tool. The rear caster spec is 0 degrees +/- 0.8 degrees, so you could assume your alignment is very close to right if both sides measure 0 degrees with the iPhone. The serious handling issues seem to be noticed when rear caster is off by a substantial amount (several degrees). The iPhone app could be a nice double check after having a shop do an alignment.
This looks like a really great find. Although the iPhone app appears to have only a 1 degree display resolution, it could still be a valuable tool. The rear caster spec is 0 degrees +/- 0.8 degrees, so you could assume your alignment is very close to right if both sides measure 0 degrees with the iPhone. The serious handling issues seem to be noticed when rear caster is off by a substantial amount (several degrees). The iPhone app could be a nice double check after having a shop do an alignment.
Ernie
I found another free iphone app called slant gauge that reads down to tenths after calibration - checked it again and my rear caster definitely looks to be within 0.1 degrees of zero on both sides. Nifty way to make sure the caster is set after alignment.
2016 Z, you are brilliant! That is exactly the solution I have been searching. My dealer got the tool but the angle measure gauge was useless, probably broken, so he couldn't measure it. I am going to check mine this morning.
From: Syracuse-Central Square New York Winer of the all Corvette race WGI 8/23!
2016 Z you should win a prize for your find! I will use that iPhone angle gauge at least once a week in my shop instead of the old eye ball test. Many times we are trying to determine for estimating purposes in the parking lot if a customers suspension is off well this makes it easy and impressive too.
We do a lot of alignments in our shop and I don't understand why they gave you more camber in the rear than the front. It wont hurt but I would not leave it there long on the street 2.1 are big numbers for the rear. I like the toe in.
I bet they had no idea there is an adjustable rear castor. Your test is right on man. Wish we didn't order the 125.00 bracket from GM recently. I'm disappointed in myself I didn't do the same as you. Want a job at my shop?
Yep..."Slant Gauge" Its not 100% user friendly, but it sure works well. Hope it helps, Ron! Only downside I can find is it cannot be zero'd to the floor like more expensive gauges, but a bit of quick math should overcome that when you have a steady floor reading.
MD - I wondered about that rear camber since from what I have read most track cars run about a degree less camber in the rear vs the front. Guess I'll see how it handles this week and adjust from there...
So...now I am obsessed. I found an app I like a little better; it seems to provide slightly more stable readings and it is more user friendly. Definitely makes checking rear caster and 4 wheel camber easy when used with a straight edge. I was able to check all 4 wheels and my rear caster in under a minute, and the readings agree with the alignment specs I just had done at the shop.
OK, so I just finished measuring the rear castor using the "2016 Z" method and found that the RT rear castor is spot on at 0-0.2 degrees. The LT rear castor, however, is off by 2.2 deg with the wheel pointing fwd. I think that explains the weird behavior of the rear in the "keyhole" at Mid-Ohio this last week.
I was tempted to try to adjust this myself but I am reminded that the camber may also change during this adjustment and since I have no way to measure that in my garage, I will let the dealer do it (no additional charge, of course) using the 2016 Z method. (Since his tool is busted.)
Unless there is a similarly easy way for me to measure camber that someone can tell me.
I am assuming that there are no adverse consequences to street driving the car as is until I can get it to the dealer. I don't plan to track it anymore for a while.
To check camber, you just need a straight edge against the tire (sufficiently forward of the bubble or bulge that occurs at the bottom of the tire, which will throw off the measurement..) and hold the angle gauge against the straight edge. Then you can directly read the camber from the app. I checked it a few times to make sure I was reproducing the correct measurement before I was certain.
I'm not 100% sure you can use his front caster measurement technique because it assumes a static 16:1 steering ratio, and the C7 has variable ratio steering, but when I checked my front caster it was within 2/10ths of what the alignment shop readings printed on my sheet.
I suspect the readings are off those tenths because of the variable ratio, but can someone with more experience chime in here?
Z06 alignment question
