VancouverL71

I am complete novice but will attempt an alignment in my garage and would appreciate a few pointers to get me on the way.
Here are the facts: 1969 Big block
I want a factory feel as I will not be on the race track.
I just put in new pscv and ram, new idler arm, new front wheel bearings, new upper and lower ball joints and new tie rod on one side. Car now wonders all over the road.

Just put it up on cement pads so I can access underneath and will shim the car level tomorrow morning and find the centerline with several plumb bobs

I plan to do the following in this order

1. front caster
2. front camber
3. front toe in

4. rear camber
5. rear toe in

I have 2 questions after reading many threads and watching many youtube videos on the alignment.

Firstly, what are the factory specs I am trying to achieve?
Is this correct
front caster 1 degree positive
front camber zero degrees
front toe 1/32" total toe in
rear camber .25 deg negative
rear toe 1/8" total toe in

I have the AIM but can't find this information in it. I beleive the above numbers came from Van Steele but have seen other versions that are very different.

Secondly, how do I measure the caster? The front camber is very easy to understand but I don't understand how you measure the caster. I read that you add shims in the back of your control arms (or decrease in front) to increase positive caster. But how do you measure where you are at. Most posts gloss over that particular point.

Any help would be very much appreciated.
Pete

revitup

Rear toe-in and camber are pretty easy to adjust with a measuring tape and level. Front alignment isn't as simple. Adding and removing shims at the control arms will simultaneously affect both caster and camber involving a significant trial and error process as you will need to torque the control arms, lower the car, drive it to settle your adjustments, measure and repeat multiple times. I wouldn't even attempt it unless it's just to get it drivable to get it to an alignment shop. Which it sounds like it already is.

revitup

As far as specs, I think it depends how you're going to drive the car.

VancouverL71

Thanks Rev,
I realize that I will take this to the alignment shop much later but at this stage the only way for me to properly understand this stuff is to get my hands dirty. 6 months ago I didn't know what a control arms/shim or tie rod was so I may miss the obvious. I will tackle this slowly and methodically.
Firstly
Your numbers are close to what I have and others I have read so I will shoot for both front and rear camber at zero degrees (easy math) and total toe in 1/32" up front and 1/8" in rear. As for the caster numbers,,, I have read various numbers on line as to what a street set up should be (1.1 to 3.3 positive, 1.0 positive, and your 2.75 positive). So it sounds to me that 2.0 positive is a good easy math target.
Secondly, as for the caster, I still do not have any idea how to measure it at home. Does anyone know? I understand that the camber will effect the caster and visa versa but what exactly am I measuring?
Any ideas? Pete

jnb5101

The caster is the amount the wheel tilts (off vertical) when the steering is turned to it's maximum in either direction. Get a magnetic angle gauge and attach it to the wheel at the top or bottom; with the steering set straight ahead, zero it; turn the steering to maximum and read the degrees of tilt. That's your caster.

revitup

Caster is an imaginary line that runs through the upper ball joint and extends through the lower ball joint. Viewed from the side, the line will tilt forward or backward. The tilting of this line is caster. If the line tilts towards the back of the car, at the top, it's positive caster. If the line tilts forward then it's negative caster. I believe it would take some fairly sophisticated equipment to measure that angle accurately. Even the most basic DIY tools are a few hundred bucks I think.

cagotzmann

Caster can be calculated from camber.
Use this as a reference.

http://www.smartracingproducts.com/s...nal_update.pdf

Read the section on caster measurements.

But the basic is measure the camber with the left wheel turned to the left at 10,15,or 20 degrees. Measure the camber.

Then turn the wheel to the right 10,15,20 degrees, again measure the camber. The total difference in camber x by

most alignment shops use 15 degrees as the reference which is what I think the specs are measured from. But the more importance is the same on both sides, referenced as cross caster tolerance. should be 0.1 side to side.

10 = 3
15 = 2
20 = 1.5

equals total caster. The instructions don't show you how to determine positive vs negative caster but I believe if the first measurement is positive then it is positive caster.

You will have to note the angles as positive and negative because to need the total change in camber.

eg reading 1 = + 1.2 degrees turned left 15 degrees

reading 2 = -.6 degrees turned right 15 degrees

difference = 1.8 degrees x 2 = 3.6 degrees caster. I have confirmed this using my camber caster gauge

http://www.longacreracing.com/produc...%84%a2+Adapter

cagotzmann

go with these numbers. I have used these many times for different driving conditions.

ignatz

I posted this earlier this year. Highlighted caster in the text.

I use the string method to set toe and it is very repeatable (provided your suspension is pretty good to begin with). To set caster and camber I built a little jig that attaches to my lug bolts with magnets. It has a front surface mirror and a digital angle cube. The cube is pretty good, maybe a tenth or two of repeatability. Caster is the trickier setting. I shine a laser pointer onto the mirror which reflects onto a poster board. With a marker I note where the spot shines and turn the steering to make enough marks to plot a line. The angle of that line gives me the axis of rotation, at least good enough to get both sides set to the same angle.

Here's what my jig looks like:



Something to note, every time you make a change, you need to move the car and get everything settled again.

cagotzmann

If you like to learn, this is a enjoyable task, but does have some drawbacks.

Drawbacks

1. If you screw it up you will kill your tires very quickly.
2. You need a lot of patience.
3. You will get many opinions on DIY methods
4. Your car will drive like crap.

Positive if you get it right.
1. Your car will always handle as it should
2. Your tires will thank you.
3. You will never waste money on shops that don't know how to align C3 corvettes.
4. It will give you confidence on doing more repairs to your suspension because you wont need to pay a shop again to align correctly.

Now to get it right has some costs to it.
The trade off is between your time and your wallet.

I use my car for track days, so it not uncommon to change my alignment every few weeks.

I have invested my interest in alignment with 2 concerns
1. my time if worth money
2. needs to be easy to repeat.
3. I don't what to remove wheels from the car. ( see # 1)

To take all the measurements I need ,it takes me a total of 15 minutes
were caster takes the most time.

So with #1 DIY String alignment went out the door.

There are many inexpensive tools that will aid in DIY alignment. example in the other post angle cube. Smart strings etc.

Camber / Caster are the easy ones for DIY. You will get many opinions on how to measure toe.

I always ask this question. How many miles do you drive your car. The only way to know how well the method works for you is tire life. Improper toe settings is a easy way to kill a set of tires.

I have found there are many settings that make the car drive and handle (track) straight on the road but still kill your tire life. Just because someone claims it never handle so well, doesn't mean they will get proper tire life. If you are learning the DIY Methods verify them with a local alignment shop. ($30 @ my dealership) measurements only.

The only tool I invested in was from longacre racing

http://www.longacreracing.com/produc...%84%a2+Adapter

This is not required as others will show you there home made rigs and you can calculate caster from camber.

One of the most important and most forgotten settings is thrust angle.
This is the relation of the rear axle to the front axle steering effect. This shows up as crabbing during acceleration, loose feeling during hard braking, car wonders in a straight line.

I use the axle lines to setup thrust angle, other use the frame of the car. I believe the axle lines should be used since this is where the wheels are mounted and take into account all the parts / tolerance of the suspension to the frame mounting. Front axle vs Rear axle.

You want the rear wheels pointing in the same direction as the front wheels. The easiest why I found to do this is using a laser level mounted to the rear wheel and measure the distance at the front axle. Compare left side vs right side. They should be the same. Then you can adjust rear toe for the correct total toe, and check again. If you set rear thrust to the frame you must assume the front axle is also correctly aligned to the frame. It most likely is off after 30 years.

Here is a good test to see how good your frame is.

Place a bar in front of you tires similar to the picture shown below. ( Picture shows how I setup for toe measurements.)

except place the bar pointing outward from the rear tires. and measure left side vs right side. They should be equal but they wont be. How much they are off will give you an idea how straight your wheel axles really are. Then you can decide on how to set your thrust angle. Use the frame or use the axle lines.



This is what I read from the scale on the bars to measure toe.

Measure to the 0.5 mm. On the line = mm reading between to line = 0.5 mm reading. This method I can measure to 0.01 degree / wheel.

The best string method can measure using a 15" wheel is 0.1 degree / wheel. This is because a human can accurately read a scale at 1/32"

Then I input my readings in a excel spreadsheet.









Enjoy the process it is very rewarding if you get it right.

VancouverL71

Wow, that is so helpful, Thanks you guys. I now I understand how to measure caster. Now I understand why most threads kind of gloss over the whole caster setup.

So here comes the 100,000 dollar question. As they all effect each other, what should I tackle first?

I just made sure the car is level from side to side. It also makes sense to me to check the axle lines and with both levels, tapes and a laser level, this should be pretty easy to do so I will go about doing that.

I have just now discovered one of my main problems. All 4 wheels have positive camber, (sticking out at the top) and two of them a considerable amount. Does it make sense to set up zero camber first. I have virtually no shims on either of the control arms so should I add equal amount front and back just to get the camber corrected at the front two wheels?

Much earlier before I understood control arms etc, DUB mentioned that I may have a problem with my cradle based on my lack of shims but it would seem to me that I should add some to straighten up my camber issue as a first step.

I assume Toe should be dealt with last??

jnb5101

caster first-it involves adding or removing shims in different numbers at both locations
camber next- add or remove an equal number of shims at both locations
toe last
the shop manual has a very good write-up on this

cagotzmann

Here is the steps I use to align my tires.

This is what I use for under the wheels when I want to make adjustments with the wheels on the ground, and to measure caster with

https://www.walmart.com/ip/Color-Fle...g-Mat/20531370

I put grease between the sheets. Some use tiles but I find the tiles break to easily.

1. Make sure the tire pressure is equal in all tires. And measure the tread depth. ( reference for later include mileage of the car)
1.a check the ride height at all 4 corners ( reference for later )

IMPORTANT !!!!
1.b check how much play you have in your suspension. Properly adjusted wheel bearings etc. If you have worn parts it will be near impossible to get the same readings time and time again.

2. I don't level the car but I do measure the angle of the floor to add or subtract camber angle readings. ( too much wasted time leveling the car when its not needed)
3. Once I measure the floor I then mark the spot for future reference and indicate if I add or subtract degree's. My floor is 0.1 degree off perfect level. So on the left side I need to add 0.1 degree of camber reading and subtract 0.1 degree on the right side. Both front and rear axles are the same.
4. Next I setup to check the axles for alignment. Measure left side vs right side.
5. Check Thrust angle for the rear wheels
6. adjust rear camber and re-check thrust angle for the rear.
7. adjust rear thrust angle ( rear wheels relative to front axle equal on both side) don't worry about the amount. Just that both are equal. It will be impossible to get perfect amount on each side but I try to get the left vs right side with-in 2 mm difference @ the front axle.
7. adjust rear toe and re-check thrust angle for the rear. Once you know the amount the toe is out adjust shims equal on both sides to maintain your thrust angle)
8. if your thrust angle is off adjust the one side and re-check total toe.



Now for the front.

1. I center the steering wheel. Check check the thrust angle to the rear axle. ( same procedure as the rear thrust ) I point a laser level to the back wheels and measure the distance from the rear axle. If they are the same then your thrust angles will be with-in 0.01 degree's. If they are not don't worry about it yet.

2. adjust front caster and make sure left side vs right side is with-in 0.1-0.2 degree's.

3. adjust front camber and re-check front caster.

4. Now its time to set the front thrust angle. Center your steering wheel and adjust the toe angles to get equal measurement from the rear axle. Once you are happy with this step measure total toe and adjust equal amounts on both side for total toe settings.

During each complete adjustment steps I drive the car around the block and re measure the settings. Some just roll the car back and forth but I found driving the car settles the suspension better. But if you are in a hurry just roll the car back and forth.

Last step check your ride height again at all four corners if everything went well they should be with-in 1/4" with a good suspension. If its out you will then need to check other parts such as springs / bushings / body mounts etc.

If all goes well your car will drive nice and straight and most important you will maximum life from your tires.

You then next move to monitoring your tread wear rate to make sure they progress equally.

There are many variations of steps people use, I used input from as many sources as I could find and refined my steps based on what as worked for me based on

the amount of time and effort to maximize precision.

Precision was based on a comparison between my measured results vs the alignment machines used at the dealership.

So if you are happy with the results the last step is to get the results verified at an alignment shop. Don't worry if you don't get the same readings the first time. You now have an opportunity to test your measurement techniques. You have known results from the alignment shop. See what it takes to adjust your procedure to match there readings. This is were I learned the most about which method to measure was the most accurate. ( why I stopped using traditional string methods )

Now the good about being close enough is your car will tolerate a wide amount of error and drive and handle well, but your tire life wont be maximized. For people that only drive less than 2000 miles a year, will replace the tires based on age before the tread wears out.

You can choose how much precision matters.

For me to get the correct setup for track days is important to maximize handling and get equal tread wear in extreme conditions.

Let us know how to make out and what you find has worked well for you. I am sure someone out there will always find another method that improves things to make it easier for all.

cagotzmann

As a note for those who have spreader bars installed, disconnect them before trying to do your wheel alignment. They throw everything off when trying to set caster / camber.

ignatz

Why do you say that? Camber maybe wants to pull or push on it? With my car sitting on the ground the spreader bar can be easily twisted by hand. That suggests to me it isn't doing anything, just then.

cagotzmann

Try removing to adding some shims I see you if you can properly torque the upper arms. If you don't disconnect you will need to adjust the spreader bar as you tighten the upper arm bolts again. It is easy to forget and may not turn freely and allow the upper arm to move properly based on the extra shims or the removal of shims.

This is most noticeable when adding -1.5 degrees of camber. I usually re-adjust the spreader bar after the suspension settles after camber / caster adjustments.

ignatz

Now that I think about how, in the stock setup, the spreader bar is actually connected rigidly to the upper arms that makes perfect sense. A very good point. I have the SPC arms, so no shims. The control arms are bolted to the frame and adjustment takes place outside of that connection.

cagotzmann

I also have SPC arms but I also shim them because its faster to change from street the track alignment and back to street that it is to turn / adjust the SPC arms a get the same setup.

VancouverL71

OK, I got started today and found some pretty messed up numbers. I did use a protractor as below in the picture but have a proper one being delivered the end of this week. Here is what I have found so far.

Camber all four wheels is positive pointed straight ahead
Left Front 1.5 degrees pos
Right Front .7 degrees pos
Left Rear 1.0 degrees pos
Right Rear 1.25 degrees pos

Caster
using 20 degrees so multiply by 1.5
Left front wheel turned to the left 1.0 pos
Left front wheel turned to the right 1.7 pos
I believe this makes it a Negative Caster of 1.05

Right front wheel to the right 1.0 pos
Right front wheel to the left .3 pos
I believe this makes it a Positive 1.05 Caster

I also found considerable Toe In on the front wheels to the tune of over 1/2 inch each side (1 inch total Toe In) And that is measuring to the front and back position of the rims but it just occurred to me that I am unsure if I should measure to the front and back of the rims or the actual tires which will likely even double the amount of tow in.

One more strange thing, I have just one shim at FRONT of my left control arm and one shim at the REAR of my right control arm?? Wouldn't this explain my problem of positive caster on one side and negative on the other.

any help would be appreciated as i now need to start moving shims.

Thanks, Pete

cagotzmann

Don't worry about what shims are where (they most likely explain your measurements), since you already know none of the settings are correct. Just when you add shims make sure the measurement is going in the correct direction. eg. if you add shims at the rear of the control arm you should get more positive caster or change from negative to positive caster. This will confirm you have the correct procedure to change and your process to measure the change is working correctly.

As for the toe start with setting rim to rim equal or just slightly less at the front rim vs back of rim. This will not get you into any trouble.

Enjoy the journey it is real gratifying to learn to align your car.