Advanced Chassis Alignment

We always try to think of the elements of a good, winning setup in terms of priority. It saves time and energy to put the most important items at the top of the list and work on them first. In Circle Track, we stress the importance of moment center design and having a balanced setup to give the car what it wants. Before this can be accomplished, you must address the critical area of chassis tuning.

We have talked about the importance of proper steering related to Ackermann as well as the alignment of the rearend. Now, we will show how to align all the critical parts so the wheels will track true to the path of the race car. Poor alignment can ruin an otherwise great setup.

A good, well-balanced setup is a product of making sure all of the elements are in place. Many times I have run across a car that has all the right ingredients of roll center design-a good balance of front and rear suspension design, and proper weight distribution. It has all the necessary components, except for one thing-it has a serious alignment problem.

Whole-car alignment is critical. Four-wheel alignment can be the final setup parameter that can take you to the front or keep you in the rear of the field. The problem is that no amount of manipulating other setup components will overcome a wheel-alignment problem. While it is probably true that a car out of alignment is more forgiving on dirt, it is important on both dirt and asphalt to have your wheels properly aligned.

1. Toe Settings - Proper toe settings at the front and the rear are important. A set of tires not toed correctly will create a lot of drag, much like applying the brakes.

2. Rear Alignment - The direction that the rearend is pointed in relation to the chassis can dictate how a car will behave in the turns. For example, on turn entry, if the rearend is pointed to the right of the chassis centerline, no amount of setup tuning will prevent the car from being loose. That looseness will stay with the car throughout the turns, especially ruining the turn exit. If the rearend is pointed to the left of the centerline of the chassis, the car will be tight through the middle and off the corner.

3. Front to Rear Tracking - The tire contact patches must track straight ahead from front to rear. In most cases, you need to line up the right-side tire contact patches. The final alignment will show the right-side patches are in line with one another along with the rearend being perpendicular to that line.

4. Ackermann Adjusted - The last alignment priority is making sure you have very little Ackermann, which is the creation of additional front toe as the wheels are turned. On most quarter- to half-mile racetracks, little Ackermann is needed to make sure the wheels are tracking inline with the radius of the turn for each wheel. Calculations show that for those tracks with fairly large radii (much more than was used to design for passenger cars for turning the corner at the stop sign), a small amount of added toe is needed to properly align the front wheels to their individual radii.

There used to be only one reliable way to align a race car. You used a string. You either measured to the tires at hub height or measured at the floor by creating right triangles on the floor. That's still a viable way to do it-and necessary for lower-budget race teams.

A quicker and more accurate way to align the car in all areas is by the use of a laser system. The key to maintaining accuracy in a laser system is to be able to check the tool to make sure the beam is truly tracking at right angles to the mounting device. The unit we used is called a True Laser Track. The laser can be removed from the hub adapter and turned to check if the laser pointed to the same spot on a target. This must be done each and every time we use the tool to check alignment.