Step 2. Bumpsteer
Several companies now produce and sell alignment equipment that is portable and easy to us
Before you begin your alignment setup and checks, you need to check and correct for any bumpsteer problems. If the car is going to be raced at a low attitude in the front, position the wheels in the range of motion the car will be running at on the racetrack. A perfect bumpsteer setup at static ride height might be much different when measured at high compression of the front end.
Step 3. Ackermann Measurement
Let's go ahead and check our Ackermann first so that we don't upset the later adjustments and settings. This is best done accurately with the laser systems. However, the "analog" method using strings and can also tell us whether we have unwanted Ackermann or not.
If using a laser system, follow the manufacturer's suggestions and recommendations for measuring for Ackermann. If you do not have a laser system, you can use strings. Here is how you do it.
Ackermann is when we gain toe as the wheels are turned. This simple method can utilize eit
Start by pointing the front wheels straight ahead. Pull a string along the outside of the tires at the tire bulge at about the spindle pin height (avoid the lettering areas). Project the line out to the front of the car 10 feet and make a mark on the floor with the string aligned with the sidewall (I use a piece of wide masking tape and a Sharpie marker). Do this for each front tire.
Then, turn the steering wheel about the same amount it is turned on the track when you're going through the turns. Again, string the front tires and make marks at 10 feet out in front. The distance between the two marks for each wheel should be the same for the left front wheel and the right front wheel if there is no Ackermann present. If those distances are different, there is some amount of Ackermann or Reverse Ackermann present.
A greater measurement for the left tire indicates Ackermann (gain in toe-out) and a greater measurement for the right tire indicates Reverse Ackermann (loss of toe-out). A 1-inch difference equals about a 1/4-inch of Ackermann or added/loss of toe for an 85 inch circumference tire. So, if you can get your differences to 1/4-inch or less, where the left side is more, you should be good to go.
Step 4. Wheel Run-out Check
You will need a tried and true plumb bob when you setup for alignment checking as well as
Check both the front wheels and the rear wheels for Run-out. This means that as the wheel rotates, the outer edge of the tire will wobble slightly. We must compensate for this slight distortion by finding the extreme high spot at a point equal in height to the hub height. We can simply use a jackstand to hold the tape steady and rotate the tire noting the distance from the stand. Once we locate the high point (seen as the least distance to the offset), we mark it with an arrow and then rotate the tire (be it front or rear) so the arrow is at the top pointing straight up.
Now, check the toe at the rearend. Use toe plates or toe bars for the "analog" method and the laser systems for a more accurate assessment. Even small amounts of toe-in or toe-out are not acceptable. Be careful how each person holds the toe plates so that the measurements are consistent. Do the measurement several times to ensure accuracy and repeatability.
I use a thin tip magic marker and place my measurement points on masking tape that is easi
When using the laser systems that attach to the hubs, remember to thoroughly clean the surface of the hub and make sure there are no protruding threads from the bolt holes. It is recommended that you go over the hub surface with a flat file to eliminate any bulges or protruding edges of metal that would cause the laser to not be aligned properly.
Follow the manufacturer's recommendations for setting up the laser systems. Remember that the accuracy of the measurements is directly related to how closely you follow the directions and how carefully you read the system. There is a logical progression to alignment and each company has put a lot of thought into the methods. The end results, if properly applied, will be the same.
Step 5. System to Frame Setup
This is what our basic alignment will look like. Measurements (a) and (b) will be the same
Once the rear wheels have been toed straight ahead, square the laser system to the frame. Most car builders will align at least one framerail parallel to the intended centerline of the chassis. It may be located on the right side or as the weight box on the left side next to the driver. You can also align the laser system to the centers between the front and rear clip rails closest to the main framerails.
For the analog method, this setup can also be done using strings. We will setup a "box" with strings on each side and at the front and rear. We use plumb bobs to make marks on the floor off the outsides of the framerails or the front and rear clip rails. For Perimeter cars, or ones with no offset in the chassis, we can split the measurement between the front and rear clip rails closest to the center section to find the centerline of the chassis.
This chart will help you determine the offset of the contact patch from the position at hu
For offset chassis, we will be able to use a straight rail, or we could again split the clip rails. Measuring between the marks, we can split the distance in half and place a mark at the halfway point, or at the centerline of the car.
Step 6. Center the Steering Box
This is another view that shows the steps to take in checking the alignment of the rearend
Center the front steering rack. This is done by turning the steering wheel lock to lock and back half the number of turns from full lock in either direction. Once mid-rack (or mid-box with drag link steering) is found, lock the steering shaft with two vise-grip type of pliers against the frame.
We want to make sure the steering is centered and the wheels are pointed straight ahead. Once the steering box has been set to center, adjust each tie rod so that the right and left wheels are pointing straight ahead. With the laser systems, this is done quickly and accurately.
With the string method, run a string down each side of the car at hub height and parallel to the centerline you have established. Then, simply measure to the side walls or wheel rim of each front tire with the tape measure and make both front and rear measurements equal by adjusting the tie rod lengths. We can set our wheel toe later on after we have aligned the car.