toobroketoretire

I have always aligned my own front ends at home and if any of you are interested in learning how I'll be happy to teach you. All you need is a simple home made tool, a tape measure, an angle finder, and some blocks of wood. Once you see how easy it is to do you'll kick yourself for not learning how to do it sooner.

cagotzmann

Do you have a results of your method vs the readings on a alignment rack. I have been working on a method over the past 3 years from tape measure / strings etc only to find they not very acurate once measured on an alignment rack. When driving the car it will drive great, but then I have found the alignment can have a wide range of settings without the driver able to notice a difference. The problem with most of the DIY Methods is the distance of the measurements / precision that the human eye can determine.

eg measure 1/32" on a tape measure is usually very good. So using the string method you are measuring over a distance of the rim width ~ 15-18" depending on the rim size. Using the standard tape method you increase this by the tire dia ~ 25-28"

The best precision with strings is ~ 0.119 degree's / wheel
With a tape measure this increases precision to 0.0663 degree's / wheel

The good part is the car will tolerate a wide range of settings without affecting drivibility / tire wear. The key is balance the left vs right and the rear wheels point in the same direction as the front.

How do you deal / measure thrust angle ?

79vetter

I would like to see a nice write-up of this procedure...

diehrd

I would like to see how for sure

toobroketoretire

As I am a "cheapie" member I can only post a single picture at a time so be patient with me.

First of all I am not using that ridiculous "string method" that I hear people speak of but rather an angle finder to read the caster angle directly off the center line of the spindle.

The first thing you do is measure the distance from your center dust cap to the surface of your garage floor then take the wheels off and rest your spindles onto blocks of wood (and other things) so it sits at the same height.

toobroketoretire

Next you make a caster angle tool using a piece of 3/16" X 1" X 21" steel with two 90 degree bends (as shown) with the legs about 10-3/8" apart. Then drill a 1/4" hole 3/8" from the end of each leg. Those holes are for hanging the tool onto the ball ends of the grease zerks of the upper and lower ball joints (as shown in 1st picture).

toobroketoretire

After hanging the caster checking tool onto the grease zerks use an angle protractor or an electronic angle finder to read the caster angle from the backside of the tool (as shown in picture).

toobroketoretire

After reading the caster angle swap upper control arm shims from front to rear (or vice versa) until you get a 2-1/2 degree positive caster angle. After setting the caster angle place your angle finder against the side of the rotor and measure the camber angle. By adding or removing shims in equal amounts from the front and rear of the upper control arm set the camber angle to zero (straight up and down).

toobroketoretire

After setting the camber angle to zero put the wheels back on and roll the car backward about 10 feet then foreword 10 feet to allow the front end to settle or "normalize". Take a stiff 25 foot tape measure and measure the distance from the inside right tire tread to the outside left tire tread in the rear and compare that same measurement at the front of the tires. You want about 1/4" shorter distance in the front (toe in) and you adjust the tie rods in equal amounts to get that shorter distance.

(When I put front ends together I always put the left hand threads on the left and right hand threads on the right so the tie rod ends can be turned in the same direction when setting the toe in. Otherwise they have to be turned in opposite directions which can get real confusing).

My method of aligning a C3 front end is just as accurate as any alignment shop can achieve with the exception of the toe in but the toe in isn't all that important as it can be anywhere between 1/8" and 3/8". Its the caster and camber angles that are really important and my method can set them perfectly.

toobroketoretire

With my method the caster angle can be measured directly off the center line of the spindle by using my home made tool and an angle finder. And as the camber angle can be measured directly off the machined surface of the rotor there is no need to take it to an alignment shop. The so-called "string method" cannot measure the important caster or camber angles so that method is worthless at best. An inexpensive lumber yard digital angle finder would certainly be easier to use because of the larger digital readout so if you wish to use my method I suggest you buy one of those.

cagotzmann

Thanks for sharing.

How do you deal with / measure thurst angle ?

toobroketoretire

This is for aligning front ends...............not rear ends. But I also align my own rear ends and use two 8 foot pieces of aluminum flat bar to measure and set the thrust angle.

cagotzmann

So what happens if your garage floor slopes 2 degrees front to back.

What is your 0 reference as a starting point ?

Big2Bird

I used that ridiculous method on a friends custom 71.
He later had it checked on a laser table, and the guy asked how a guy in a driveway nailed it right on, all around.

toobroketoretire

If you want 2-1/2 degrees caster and your garage floor has a 2 degree slope then you set it to 1/2 degree.

toobroketoretire

Its impossible to measure the caster and camber angles with a string pulled tight along the sides of the car. If a laser later confirmed it was within specs it was already within specs. Think about it for a moment.........how can the inclination of the spindles be measured with a string pulled tight along the sides?

oldgto

usmilret

This is the kind of post that passes the common sense test. I have performed alignment checks before and I smack myself thinking "why didn't I fabricate a special tool like this one before?"

Anyway, if you would like to know the difference.

For the Front End.

1.Toe in and Toe out--is the amount front wheels are closer together in front then at rear at hub height.

2. Camber-- is outward or inward tilt of the wheel at the top.

3. Caster-- is the degree of tilt of steering axis forward or backward from vertical centerline of wheel. Caster is the steering angle that uses the weight and momentum of the chassis to lead the front wheels.


The front end steers the vehicle but the rear wheels direct the vehicle, this is called the thrust line.

For the Rear End.


1. Toe in and Toe out.
2. Camber.

Torqued Off

I think there is an issue with the validity of this, based on the one comment on slope of floor. It all looks correct, except how do you know if your floor is a good zero reference? I imagine, but do not know, that alignment racks have a way of setting a good zero reference point. I appreciate the logic of this way of doing this, but just wanting to understand the zero starting point is something we can trust with our own floors? I know mine is not perfectly flat in any direction for sure....maybe in some spots, but how do I know?

leadfoot4

Next time you're in an alignment shop, take a look at the "feet" of the rack. You'll see shims underneath them. When the rack is initially installed, it's physically leveled (if done properly), or as they say in the industry, "leveled to the horizon". Therefore, when your car is sitting on the rack, it's as level as it's going to be.