Measuring your chassis for alignment is the very first step in setting up the car. The use
As promised, I'm embarking on a journey through the most basic, and most important, race car setup steps. I'm doing this because we all need to refine our chassis setup knowledge, regardless of our place in the points standings. No matter how long (or short) you have been racing, I believe you will find something in this series that will help you better prepare your race car. And we will present the topics in a practical progression.
Yes, I have previously covered most, if not all, of the subjects you will find in this series. But what I will now do is add important information that I have acquired from very smart racers over the years. And I'm going to present the information in a more complete way with better explanations as to why we need to do each step.
This way, we can all learn and move forward with a better program. So, I encourage each and every one of you to pour over these articles and find those bits of information you might have missed, not known about, or maybe not fully understood before, like I did.
If you are new to the classes of racing where you can make widespread adjustments and are confused as to what you need to do to be competitive, this is it. The guys who are spanking you week in and week out know this stuff well. Make no mistake, you need to follow these basic steps in order to be in a position to be successful.
In past articles that are available online at www.circletrack.com, each of the routines we mention is explained in more detail than we have room for here. I encourage you to go to our website and read those articles. There are also many books available to explain how to do bumpsteer and more. So, let's get started.
There are several scenarios that create the need to check and adjust our race car's alignment. It's critical to know which way all four wheels are pointed at every point on the racetrack. As the car goes through a range of motion from accelerating down the straights through negotiating the turns, all four wheels are in some transition from their static location at normal ride height, and the direction they point can and does change.
If you have taken delivery of a new chassis, acquired a used chassis, had a major crash, or are just trying to find out why your car does not work well, you need to go through a complete chassis alignment routine. So, here is what you do, step by step.
Step 1—Establish, or reestablish your chassis ride height. This can be anything you desire, but once you determine what works for you, stick to it from now on. Be sure not to cut the minimums too close. At many tracks, there remains a minimum ride height that must be in place at the end of the race or you are disqualified.
Most car manufacturers and car builders have already determined the correct ride heights and the car was built to those specifications. You'll be closer to your destination if you follow their guidelines from the start. If in doubt, just give them a call. I will say here that setting up a car to 4-inch ride heights when it was designed for 5-inch heights will cause all kinds of problems and you have a lot of work to do.
If you are running on bumps, that puts the front end 3 or more inches lower than normal ride height, it won't hurt you to add a quarter inch to the lowest static ride height to avoid possible complications later on with the tech crew.
Step 2—You need to now set your static caster and camber amounts, as well as the static toe settings for the wheels. This is important because it helps to establish the control arm angles and the tie rod angles for future work.
Center your steering before setting toe. With the steering centered, I usually point the right front wheel straight ahead and toe the left front out the required amount. Or, you can split the difference between the two front wheels, whichever you choose.
While you're at it with the toe plates, check the rear wheels for toe. The rear wheels need to be exactly parallel to each other. If not, have the rearend straightened before you get started.
If you are new to this type of car, you might not know exactly what casters, cambers, and toe-out you need. You can ask a fellow competitor what they use and follow that advice for now. These are not considered setup secrets. You might need to refine those amounts in the future, but you probably won't need to change much.
Step 3—Use strings, lasers, or a fixture to establish the static alignment of all four wheels. What this means is; the rear wheels are pointed straight forward perpendicular to your datum line and not to the right or left. The right rear wheel is inline (or some offset left or right to your liking) with the right front wheel. We usually measure this at the tire contact patch or very close to it.
To establish the datum line, many teams use the centerline of the car, mostly representing the mid-point of the front and rear clips. For an offset chassis, other methods work to establish a line of reference like using the straight rail. Once you establish your reference line, mark it on the chassis so that you can go back to it for future alignment checks.
Take your time through this process. Make very accurate measurements at each phase. This may take some time, but it is critical to every other component that this be done correctly. You'll need a few other hands to help with this and it's a good way to get the team together and help them really understand the car.
Step 4—Next check your right and left front wheel motions for bumpsteer. That means that when the wheels travel up and down, there should be very little steering motion and they should stay pointed in a common direction. The acceptable amounts vary among experts, but less than 0.020-inch of toe change is desirable in the distance the wheel will travel on the track.
With the movement to softer setups for both dirt and asphalt cars, the range of this motion has necessarily changed. We now see more compressed movement, or bump, with both front wheels, whereas in the past, the left front wheel did not move very much vertically through the entire lap.