The upper control arm attachment...
The upper control arm attachment on a Dirt Late Model offers the opportunity to easily remount the arm for antidive and redesigning of the moment center. All you have to do is weld on a new set of bungs in the desired location and reattach the control arm. We have done just that with many Late Model cars.
Brake bias influence can easily be determined for any race car by entering the corner with medium to heavy braking first and then entering with light braking to see if there is a difference in the car's attitude. If there is, try to adjust the brake bias to improve the entry conditions under heavy braking to what it is under light braking.
8. Bite Off The Corners
We could always use more bite off the corners on dirt. The exit portion of the track provides little traction and most corners are usually more flat. We almost always need to develop more rear traction upon acceleration. To give the car more rear traction, we need to understand a little about the dynamics at work on the car when we are accelerating.
We should work to develop ways to create more rear traction on acceleration only so we don't ruin our mid-turn handling. There are several ways to do that without changing the handling at other points around the racetrack. One way is to reduce the "shock" of sudden application of throttle and torque to the rear wheels.
We can use lift arms and pull bars with various stiffness of shocks and springs. More and slower movement is needed for slick conditions and much less movement for the tackier conditions. Another way to gain bite involves the use of a spring-loaded pushrod that allows a certain amount of forward right rear wheel movement to steer the rear end more to the left.
9. The Antis
Dirt cars have been modified...
Dirt cars have been modified over the years to a more aerodynamic wedged shape where the oncoming air is directed over the top and around the sides of the hood and not under the car. This will produce a significant amount of downforce due to creation of low pressure areas under the hood. Note the flair around the wheel wells.
Antidive and antisquat are mechanical influences that can help our transitional phases of entry and exit. We can regulate the amount of both depending on the need. A small amount of antidive on our dirt cars can help prevent sudden nose dive on entry by utilizing mechanical resistance to the downward motion of the suspension.
Antisquat results from the pull bar trying to straighten out, or become more horizontal as the car accelerates and the rear end desires to rotate. The more pull bar angle you have, the more antisquat there is. The lift arm also creates antisquat and can actually lift the rear of the car on acceleration. Lateral movement of the front end and/or rear of the lift arm can alter the loads among the two rear tires upon acceleration.
10. Aero Package
Racers discovered the need for better aero designs some years ago. Just look at the Dirt Late Model cars and how they have evolved. The front ends are wedges that scoop the oncoming air up and over the car. The wheel wells are shaped to route air out and away from the front tires creating downforce.
The degree that you need to get involved with aero for your car depends a lot on what you run and where. Aero influence varies with the speed of the vehicle. There is an algebraic increase in both drag and downforce associated with increases in speed through air. That is why a car with twice the horsepower does not go twice as fast.
Try to understand how aero downforce is created and then configure your car so that you take advantage of every area where you could produce more downforce. On dirt, we need the most loading on our front tires that we can get and aero generated load is not weight we have to accelerate.
The ideas we have presented and the methods we preach have a basis. I would never promote technology that I haven't seen work. I would rather not say anything rather than mislead. No one has to buy into any of what is printed here, but you do need to think out your particular setup and how you attack your racetrack.
To be more successful, it helps when you get your car set up correctly for the basics of geometry, alignment and balance. Develop a proper approach to the setups for the tracks that you intend to race at and be prepared and willing to make changes to your setup when the track conditions change. That ideology will never change.