The lift arm attaches to the...
The lift arm attaches to the rear end housing and runs forward to an attachment point. The movement of the arm is controlled by a spring and shock on acceleration and on a spring when the car is braking.
Tire Grooving and Siping
As track conditions change, so do our needs pertaining to tires. We usually have the opportunity to change the grooving in the tires to increase the grip and to help control heat buildup. This is a highly complex subject and best left to experts such as Professor C.P. Furney Jr., who took the time and effort to help us dirt racers understand more about dirt Late Model tires by writing a book about it. Selection and Application of Late Model Dirt Racing Tires is a comprehensive and detailed discussion about the properties of dirt tires and how to utilize them for different conditions.
We can change the characteristics of our dirt tires by understanding how the conditions of the track, at any given moment, affect the surface rubber on the tire. The idea is to help the tire produce the maximum allowable grip by making appropriate changes to the tread pattern by cutting (siping) or grooving. How do you do that? Read the book.
Dirt Car Aerodynamics
Most dirt racers probably do not agree that aero has a profound effect on dirt cars. For the most part, they are more right than wrong. On the other hand, aero may play a major role in dirt car performance, and our understanding of it may answer some nagging questions as to how certain setups work well and others do not.
When we examine the shape of the dirt car, we see large, flat sides, wedge-shaped noses, large rear spoilers, and open rears around the bumper. These are shapes that can produce considerable aero effects, both good and bad.
The fifth coil, which controls...
The fifth coil, which controls the acceleration forces, is to the rear. The sixth coil, which controls the braking forces, is to the front.
If you have ever observed a dirt Late Model car cruising through the pits at around 10 or 15 mph, you may have noticed a lot of dust billowing out of the back of the car. Have you ever wondered why there is so much disturbance of the dust on the ground? A pickup truck can go by and not move any dust, so what causes the difference? It is the suction created by air being pulled out of the back of the car as it moves through the air and sucks the dust up off the ground-and this is at only 10-15 mph. Think of the effect at 60-80 mph in the turns.
So if we agree that there is a low pressure effect and with it some amount of downforce, we might try to utilize that effect to our advantage. The car's attitude works to improve downforce or destroy it. Many racers struggle with a car that pushes on exit when the LF wheel, and the nose, is hiked up a foot or more off the ground. No wonder it pushes; the car is catching a lot of air under the LF, and that might cause aero lift instead of aero downforce.
The car might stick better up front, through the middle, and off the corner if we can keep the LF corner down and allow the aerodynamic downforce to work. All is going to be lost once that LF comes up as we accelerate.
Tight, Moist Tracks
Most dirt tracks start an event with a lot of moisture due to the crew watering and/or tearing up the surface prior to the event. The conditions do not usually change much from practice to qualifying, and the surface may become even more moist if the crew waters the track prior to the qualifying runs.
The trend among top racers has been to run more even spring rates across the front and rear and a more level track bar to balance the setup when there is a lot of traction. The bar may even be mounted on the right side of the chassis for more consistency. We need all of this when the tracks more closely resemble asphalt conditions as the G-forces increase. We can then utilize all four tires and a more level body configuration relative to the track surface to improve the aero downforce that exists.