Alignment by GT350Clone
Originally written by GT350Clone in 2003
In the course of building & sorting the car, we had experience with several alignment shops. Most “production” alignment shops are equipped to deal with a “shim-adjusted” front end, or they just don’t want to mess with it for “$49.95”. The third shop we dealt with looked at the modifications, and demanded $65/hour to align the car. After the $300 mark, we begged them to stop. NONE of the shops we dealt with were able to diagnose the “real” problem we were having with SEVERE bumpsteer.
After those experience, we did a lot of reading, and bought/made our own alignment equipment for under $100. Following is my method for “Home Alignment”.
As far as specs… For most vintage Mustangs, you’re looking for -1/2* camber, +2* to +3* caster, and 1/8″ toe-in. For more aggressive driving, run more negative camber. For power steering cars, strong arms, or lots of highway stability, run more positive caster. Track guys should read tire wear and temperatures and adjust alignments according.
You do need to have the car on a level surface – not hard to do at all. You can use 1×6’s and/or sheets of masonite under the tires to get it level… I made my own front slider plates from steel plate and dowel pins.
The “shop alignment” that you get is only as good as the operator, and there is a LOT of tolerance in the specs. Operators are paid based on how many they do, not how well they do them. While -1/4* may be the camber spec, you could end up being +1/4* on one side and -3/4* on the other and be “within spec”. Home alignment tools are usually accurate to with 1/8*, so if you’re willing to spend the time, you can be much more accurate. The tool cost will pay back on your first “regular $50” alignment.
You MUST have a level, smooth garage floor.
You need a tape measure.
I made my own slider plates from 1/2″ thick steel plate 12″ x 12″, which I lay down on top of some 3/8″ x 2″ steel dowel pins. This will allow your tires to slide on the floor instead of binding and changing your readings.
A Caster/Camber gauge REALLY (HIGHLY recommended) helps (about $50). It will get you within about 1/8 degree. Without one, you can get within 1/2 degree though. They are available from most race shops, even J.C. Whitney!
If you don’t have a C/C gauge, you will need an 18-24″ level that can be read vertically.
Get the front tires on the slider plates with the dowels under the plates. I also lay some 1 x 6’s down and slide them under the REAR tires just to keep the car level front to back. (That 7/8″ front-to-back will affect caster reading…)
SET CAMBER FIRST.
Camber is the top/bottom tilt of the tire as viewed from the front. You want camber from between 0* and 1/2* negative (which means the top of the tire is tilted in). If you are using a level, you will hold it vertically touching the rim top and bottom – for each 1/8″ you move the level away from the RIM (not tire), you have 1/2 degree. If you move the TOP of the level away from the rim, that is NEGATIVE camber. If you move the BOTTOM of the level away from the rim, that is POSITIVE camber. SO, you will want the RIM to be somewhere between EXACTLY vertical, and tilted IN 1/8″ at the top.
SET CASTER NEXT.
Caster in the least critical for tire wear, but will cause you car to “pull” to one side if it’s too far off.
Turn the front of the wheel 20 degrees “out”. (1.5 turns with “slow” box, 1.25 turns with fast box, 1 turn with 15:1 Rack & Pinion)
Measure Camber. (If using a level instead of a gauge, each 1/8″ of space between the level and the rim = 1/2 degree)
Turn the front of the wheel 20 degrees “in”.
Take the “out” reading (usually a positive number), and SUBTRACT the “in” reading (usually a negative number) from it, then multiply by 1.5. That is your caster reading.
Out = -1 degree
In = +.5 degrees
-1 – .5 = -1.5 * 1.5 = -2.25 degrees (NEGATIVE) caster. (THAT’S BAD!)
Out = +1 degree
In = -.5 degrees
1 – -.5 = 1.5 * 1.5 = +2.25 degrees (POSITIVE) caster.
MATH NOTE: In the above example, you are subtracting a negative number from a positive number. Two negative equal a positive, so you essentially just add the two numbers together!!!
Ideally, you want 2-3 degrees of positive caster per side. To get MORE positive caster, add shims to the front upper a-arm bolt on 65-66, or shorten the strut rod on 67-up. Some cars will not get more than 1 degree of caster on 1 side or the other due to factory tolerances, tweaks, or wrecks over the years. The amount of caster is not as important as making sure it is EQUAL side-to-side.
DO TOE-IN LAST.
Make sure the steering wheel is centered and STAYS centered. You have 2 good ways to do this…
1) Using a tape measure, you measure the distance between the front tire at both the front and rear of the tire. The front measurement needs to be 1/8″ LESS than the rear measurement.
2) Tape a piece of kite string to the rear tread of the REAR tire at about the height of the center of the wheel. Stretch the kite string to the front of the car, holding it away from the tires at the height of the center of the wheel. Move the string toward the car until it JUST touches the backside of the front wheel. Measure the distance between the front of the front tire and the string. It should be 1/16″ on each side.
Copyright © 2003 GT350Clone.com
Last modified: August 20, 2009
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