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Last summer I had my '72 aligned because the tie rod sleeves had been completely removed, everything cleaned up,andI had just spent $850 on new tires.
This is the outcome of that alignment. I was disappointed because the guy didn't seem to abide by my request to increase caster as close to 2.75 as possible. Comparing the before (not shown here) and after, I don't think he touched it.
I then was gifted the Gyraline phone cradle and app for Christmas and went about increasing caster and adjusting camber and toe as it changed. The car has a slight rightward drift as it's going down the highway so I thought I'd get new readings on how it's set up. The alignment guy said the difference in caster is likely causing the drift. He didn't do anything to the car and suggested I equalize the caster better. (He also mentioned that the trailing arms need new bushings and alignment.)
What are the opinions about these readings? Thanks so much!
With radial tires you want to get about 6 degrees of positive caster. With the stock control arms/shafts you’re about at what the limit of what you can get without too much negative camber, but you might be able to get away with a little more. After that offset shafts or different arms will be the only way to get more.
The back isn’t horrible, but like you say it has worn out bushings. I would get that fixed first and get some stainless steel alignment shims. You’ll be able to dial it in much better without it being able to move around as much.
I doubt you can get 6 degrees of positive caster with stock components. Perhaps you can with offset arms. You absolutely can with SPC adjustable UCAs.
If you have the means, you'll be better off following @cagotzmann's instructions, and doing the alignment yourself. The tools will pay for themselves after a few alignments.
My big issue is the 1/4" of toe in the front.
Excessive tire wear.
If you have radials, I like much less.
Like 1/32" or zero.
And yes the caster stagger will make it drift.
Thank you leigh.
I'll try to increase the caster on the 2.7° side to get closer to the driver's 3.8°. If I can retain the camber about where it is, is the camber measurement OK?
I'm not sure I'm understanding or maybe my pic was too low for resolution. Total toe is .26° which robrobinette:ConvertToeDegreesToInches says is 1/8"... am I wrong? I can certainly bring the tie rods together a fraction after I equalize the caster.
I doubt you can get 6 degrees of positive caster with stock components. Perhaps you can with offset arms. You absolutely can with SPC adjustable UCAs.
If you have the means, you'll be better off following @cagotzmann's instructions, and doing the alignment yourself. The tools will pay for themselves after a few alignments.
Thanks Bikespace. I've read and reread cagotzmann's posts multiple times trying to wrap my head around the different alignment measurements and how to achieve them.
Yeah, I felt like the shimming to get the 3.8° was about the maximum I could do for bolt thread stick-out. If I can get the passenger side closer to that I'll be happy.
I am using the Gyraline alignment tool that came out very late last year. It's an iPhone cradle and app that you register against the wheels for measuring. It seems to be working as I'm getting closer to what's recommended than the first alignment last summer (first pic in #1). I went to the alignment shop to get verification that I was on the right track - they didn't even charge me to do the read-out, so it was definitely a win and much appreciated.
I found this info on another Corvette forum posted 10 years back and think it's a very handy "for this, do that". I reformatted it, cleaned it up, and saved as a PDF.
I guess I am a bit of an alignment nerd. I autocrossed for 27 years and always did my own.
That said I really like Van Steel's alignment recommendations for our C3s.
Especially the advanced street version.
Unless you are autocrossing, I see zero reason to run more than 0.5* camber.
Front toe-in should be near zero.
Your tires will wear 1/2 as much.
Caster and camber should be the same on both sides. Not close, the same.
Put as much caster in, after you set the camber, as you can get, while keeping both casters the same.
I can not stand the whole "staggered caster to compensate for road crown myth".
I call B.S. on that. I have never seen two roads that have the same crown. And interstates vary in every lane.
And I hate a car that steers left in one lane and right in another.
But the rear of a C3 should have 1/8" toe-in, no less.
I guess I am a bit of an alignment nerd. I autocrossed for 27 years and always did my own.
That said I really like Van Steel's alignment recommendations for our C3s.
Especially the advanced street version.
Unless you are autocrossing, I see zero reason to run more than 0.5* camber.
Front toe-in should be near zero.
Your tires will wear 1/2 as much.
Caster and camber should be the same on both sides. Not close, the same.
Put as much caster in, after you set the camber, as you can get, while keeping both casters the same.
I can not stand the whole "staggered caster to compensate for road crown myth".
I call B.S. on that. I have never seen two roads that have the same crown. And interstates vary in every lane.
And I hate a car that steers left in one lane and right in another.
But the rear of a C3 should have 1/8" toe-in, no less.
Camber first, then caster, the toe-in last.
That's a good setup. I wonder how much wandering will remain until the OP takes care of the trailing arm bushings. Strut rod bushings, too, or do you already have heim-jointed strut rods?
Originally Posted by barkingrats
(He also mentioned that the trailing arms need new bushings and alignment.)
That's a good setup. I wonder how much wandering will remain until the OP takes care of the trailing arm bushings. Strut rod bushings, too, or do you already have heim-jointed strut rods?
This car is set up very stock and original.
I've not noticed any sensations of steering from the rear. Here are the rear readings from yesterday's rack measurements:
I'm getting confused on toe in and toe out as it relates to positive or negative measurements... Is the left rear toe in by .15° because it's a negative?
Unless you are autocrossing, I see zero reason to run more than 0.5* camber.
Front toe-in should be near zero.
Your tires will wear 1/2 as much.
Caster and camber should be the same on both sides. Not close, the same.
Put as much caster in, after you set the camber, as you can get, while keeping both casters the same.
But the rear of a C3 should have 1/8" toe-in, no less.
Camber first, then caster, the toe-in last.
So here is what my measures are compared to Van Steele's "advanced street":
Changes to make are to decrease the left caster 3.8° to 2.7°. (I don't think the right side a-arm bolt can accommodate more shims but I'll double check that before decreasing the left side.)
Then decrease camber for both sides just a small bit.
Toe seems really close to zero now but after the two adjustments above try to get zero degrees/inches.
Camber: Looks good. Under .5. Both within .2 No worries.
Caster: One side will always limit the caster.
If your right side bolt is maxed out and you have 2.7*, then that is all you can get.
I would make the other side the same. At least within a tenth or two.
Toe-in: Last Shoot for closer to zero total on the front.
1/32" or less. Same as .09* degrees. Total.
Rear:
Camber : good
Caster: not adjustable
Toe: You want 1/8" toe here, or a tad more, due to the rear suspension, and bump steer. Total toe.
1/8" = 0.3* degrees
You are still way low at .08*. The rear will steer (twitchy) if you do not go over 0.3*
Tip:
Pry on the rear T/A bushings with a crowbar and make sure they are solid and do not move (more than 1/16" or so). Same self steering issue if they move.
Then tap the shims in lightly tight with a hammer when you change them. No slop.
If you can get the toe the same on both sides, you will have zero thrust angle. That is usually difficult. A small thrust angle is no big deal. It just means the front tires tracks 1/4" to the right of the front tires, etc. If it gets high it will be more difficult to keep the steering wheel centered.
Mr Barkingrats,
I can't add much to your discussion about the alignment numbers, but I would like to hear your experience with the Gyraline tool. I got one about the same time you did, but I could never get it to replicate the numbers. I got my adjustment where I thought it should be, but when I did it over, just to check, it always came out different. The people at the company where great and tried to walk me through it, but not much luck. They even sent me another tool in case there was an issue with the original one, but it was the same. I can't even count how many times I tried it, but could never get the numbers to repeat. I was very disappointed since it seemed to be a great idea. I am obviously missing one tiny little detail but cannot figure it out.
I found that to repeat I had to be very careful to place the cradle on the same spot from reading to reading. Putting small Sharpie dots where the pads contact the wheels helped achieve this along with making sure the pads were only contacting the flat of the wheels "below" the radius that creates the rim's lip. I got repeatable results after some practice.
I may not have been clear about the sequence of alignments for the car:
Had an alignment done last summer, I don't think he touched anything but the toe. The outcome wasn't very close to the measures I had asked for (same Van Steel doc Leigh provided above).
Got the Gyraline and then did initial adjustments about March. It is very rainy here in the winter and spring so I didn't get the car on the road until May. It has had very sloppy steering since getting it on the road last summer. While I was under the car for other reasons I saw that the bottom of the rag joint was torn. I changed that a week or two ago which greatly solved the skittish steering.
I didn't do another check with the Gyraline because I wasn't very confident in my own interpretation of the readings and decided to see what a shop's readouts would be. These latest readings indicate the Gyraline worked because you can see I was able to get it closer to what I was after.
Overall, I think it's more accurate than the string/laser method using a tape measure. I've also read that the repeatability of these digital readings on a shop rack is not exacting, so if the Gyraline varies 2-hundredths of an inch (mid-precision setting) this way or that, it's not a concern. Another thing... it's a street car where the tires are going to age out long before the tread is used up.
If you don't want to make your own out of cutting boards and grease, you can pick up a pair of turn plates, too.
What makes you say it doesn't work?
For ease of wheel turning, someone recommended using plastic grocery bags beneath the tires. I found this works very well!
Mr Barkingrats,
I can't add much to your discussion about the alignment numbers, but I would like to hear your experience with the Gyraline tool. I got one about the same time you did, but I could never get it to replicate the numbers. I got my adjustment where I thought it should be, but when I did it over, just to check, it always came out different. The people at the company where great and tried to walk me through it, but not much luck. They even sent me another tool in case there was an issue with the original one, but it was the same. I can't even count how many times I tried it, but could never get the numbers to repeat. I was very disappointed since it seemed to be a great idea. I am obviously missing one tiny little detail but cannot figure it out.
Probably has a MEM's accelerometer. Got this online:
What is the resolution of the accelerometer on the iPhone? Both of these accelerometers can operate in two modes, allowing the chip to measure either ±2g and ±8g. In both modes the chip can sample at either 100 Mhz or 400 Mhz. Apple operates the accelerometer in the ±2g mode (presumably at 100 Mhz) with a nominal resolution of 0.018g.
I think that only about one degree of resolution. You might try orienting your phone in all three axes and see if you get the same value for G. I played around with the chip once to see if I could integrate deceleration twice to get 70:0 braking distance but gave it up as not accurate enough.
OK, this sounds like what might be going on. I knew the Gyraline needed to be placed on a flat level surface before starting, which I did. But if my phone isn't calibrated correctly, I can understand not getting consistent results. I can see what I will be doing this weekend, taking my phone apart looking for the gyroscope...or maybe just calling my grandson. Ignatz, thanks for the idea.
I too tried the Gyraline.
I thought it was a great idea.
But I have an android, Google Pixel phone.
No repeatability at all.
Yet my compass app works extremely well to one degree.
Any ideas?
I am not sure if it is the phone, or the app just not being android friendly.
Ah never mind.
I just checked their website again.
When I bought it they said they were Beta Testing Android.
Now they say IPhone Only
Waste of $100.
Last edited by leigh1322; Jul 17, 2025 at 09:13 PM.
When I bought it they said they were Beta Testing Android.
Now they say IPhone Only
Waste of $100.
You should be able to pick up an outdated iPhone for next to nothing, wouldn't need cell service, just wi-fi to download the app. I use my wife's old iPhone 7.
Alignment Results - Opinions?
