Aligning the front end of your car can easily be done in your garage. Sure, you could just take it to a local shop that does front end alignments, but they probably will not have the proper equipment to align a racecar. Using the information in this article, you will be able to align the front end of your racecar whenever you want and do it cheaper and more accurately than at an alignment shop.
Before You Begin
You will need some specialty tools to align your car but do not let that throw you for a loop. The tools required to align your car using the method discussed here should cost you less than $300. These tools include a digital protractor with alternate reference and hold options, a scribe, a tape measure and a toe gauge. (note: Dennis @ Oval Speed in Massapequa stocks Caster/Camber Gauges for about $150, Oval Speed - (516) 541-7920 4786 Sunrise Highway, Massapequa NY (behind Caldwell Banker real estate office)
Many of these tools are used for other things and may already be in your toolbox. They are all fairly straightforward tools to use and once you have aligned a couple of cars, aligning the front end becomes simple enough that you can even make a few bucks helping others align their cars.
Prior to aligning the front end, it is very important that the car be race ready with the driver weight in the driver’s seat. This includes having the weight of all fluids in the car, the car at ride height and the driver’s weight in the driver’s seat. I recommend scaling the car before it is aligned so that all weight ratios are correct.
Caster
Caster is the inclination of the top and bottom ball joints. This is a critical measurement and should be made using a digital protractor.
The top ball joints should always be further toward the rear of the car than the bottom ball joint. This is positive caster. Positive caster places the tire’s center of drag behind the steering pivot for self-alignment at speed. Caster, for most door cars, needs to be a minimum of 5° but, for most strut-type cars, 10° is the preferred setting. If you have a stock front suspension, you might have a hard time getting 5°. Try to get as much as you can.
Adjusting caster is merely a matter of making adjustments that move the top ball joint toward the front or rear of the car. For instance, to add more positive caster, you make adjustments that will move the top ball joint toward the rear of the car. On the front side of the top a-arm, this is accomplished by either lengthening the rod end or removing shims. On the backside of the a-arm, you want to screw the rod end in or add shims. This forces the top ball joint to move back and increases caster. As the ball joint moves back, it will also want to come in. You will have to space the entire a-arm out to keep the camber at the correct setting or adjust the bottom a-arm in if it is adjustable. It is very important that both sides of the car be set exactly the same.
Setting caster on a strut car is definitely easier. Adjusting caster is accomplished by increasing or decreasing the length of the rod end on the front lower control arm. If you need more caster, you need to shorten the rod end. This will bring the bottom of the a-arm forward causing an increase in caster. Lengthening the rod end will push the bottom of the strut backward to give you less caster. At the same time, you need to adjust your main a-arm, which goes straight in toward the frame to get the camber correct.
The angle measurements of caster are easily made using a digital protractor; however, stock-type spindles can make it a little more tricky. I have found that on most spindles there is a flat, machined area in the ball joint area. This machined area should be machined true to the centerlines of the ball joints. To get an accurate measurement, it is important that you keep the digital protractor parallel to the side of the wheel at all times when setting the caster. There are some companies that have caster/camber gauges available but most of these are magnetic and are hard to use with the aluminum wheels most drag racers use. (note: most alignment gauge companies also make threaded adapters to bolt on to spindles (most GM spindles are 7/8 fine thread)
Camber
Camber is the angle of the tire as you are looking from the front of the car. Negative camber is when the top of the tire is leaning in and positive camber is when the top of the tire is leaning out. On most drag cars, try to keep the camber as close to 0° as possible. Camber angle is also critical and requires precise measurement. I suggest using a digital protractor to obtain the measurement. Caster/camber can be checked fairly easily, but if you have front disc brakes, the process is extremely simple. You simply place the protractor against the rotor at 90° to the ground and set your camber to 0°. It is good to check the camber change by jacking the car up until the front suspension is at its limit. Check the camber here and then lower the front suspension all the way down and check the camber there. It is important to check your camber change before the car is complete because the only way to adjust your camber change after it is built is by changing the mounting of your top a-arms or the mounting of the a-arms on the strut.
To adjust camber on an a-arm car, screw both rod ends on the top in or out (or by adding or removing shims on the top) or adjust your lower control arm in or out if it is adjustable once your caster is set. On a strut car, adjust the rod end in or out on the main control arm (goes from the main frame rail to the bottom of the strut).
Now that you know how to align the front end of your racecar, make sure that it is done at the beginning of every race season (if not more often). If you have any questions about the specific settings for your car, make sure you check with the manufacturer of your components.
Setting Toe
What is toe? Toe is simply the distance between the centers of the tires measured on the front side of the tires and on the backside of the tires. Toe in is when the tires are closer together in the front than they are in the back. Toe out is when the distance between the tires is greater on the front of the tires than on the back of the tires. In drag racing, toe out is not acceptable.
It is very important that the driver weight be in the car when setting toe in! Jack up the front of the car and have someone spin the tire as you scribe a line as close to the center of the tire as you can. When you do this, be very careful to make sure the car does not move back and forth as the tire is turned. Do not scribe the line any deeper than necessary to see the center of the tire. Once the tires are scribed and the car is back on the ground, you have to push the car backward approximately 20 feet. Then push it back forward and stop in the same location with the front wheels parallel to each other and aimed straight forward.
I use a trammel-type toe gauge to check toe. Place the toe gauge behind the front tires and set it on the scribe lines. Then move it to the front and set it on the scribe lines. You want to have between 1/16" and 1/8" toe in (lesser measurement on the front of the tire compared to the back). If you make any changes in the front suspension, you need to repeat this entire process to make sure that your toe change is correct. In order to get an accurate measurement, make sure that the last movement of the car is forward.
Checking Toe Change
After toe in is set, you want to jack the front of the car up until the shocks run out of their travel. Put the toe gauge on the back and again set it on the scribe lines and move it to the front to check toe change. If you have 1/16" toe in on the ground, you want to make sure that you have 1/16" toe in when the car is jacked up in front as well. If not, add or subtract washers between the tie rod rod end and steering arm until you have the correct setting. Do not use an excessive amount of washers between the tie rod rod end and the steering arm. Once you have your setting, you can make a spacer to the correct height you need. The spacer should be beveled so that there is no binding occurring between the rod end and the steering arm. You should never use more than 1/2" of spacing unless the rack is mounted in the wrong location.
Toe and front-end alignment are very easy to set yourself and both are important to the overall performance of a racecar. Using the few simple tools listed in these two articles, you can easily setup the front-end of your car without the extra expense of taking it to an alignment shop or chassis builder.