For dirt cars, where a lot of vertical movement is desirable to get more weight transfer on dry-slick racetracks, reduced compression and rebound may be helpful, and a lot of movement should be expected. Of course, this depends on the track conditions. The tighter the track, meaning the more grip, the more we need to control the suspension movement by stiffening the shock rates.
The angle of the trailing...
The angle of the trailing links can be used to cause rear steer to the left upon acceleration as the cahssis squats. We need to be cautious with this effect, as overdoing it will cause excess rear steer to the right at mid-turn as the left side of the car is raised.
7. POOR FORWARD BITE
]At the higher-banked racetracks, we usually do not have a problem with traction off the corners because of the downforce created by the banking. On many flatter tracks, it may seem like we can never get enough bite.
Bite can be enhanced by several methods: a) use of a softer RR spring (only 10-15 pounds on asphalt and more on dirt); b) use of a pull bar or lift arm to reduce the "shock" from the initial application of power to the rear tires when we get back into the throttle; c) introducing rear steer as the car squats on exit. This is done using the rear trailing arm angles and/or a height differential of the links.
On a three-link rear suspension, a higher trailing arm angle (front pivot mounted higher) on the left trailing arm will push the LR back as the car squats on exit, providing rear steer to the left and promoting forward bite.
On a four-bar rear suspension, the arms can be positioned to provide rear steer similar to that of the three-link as the car squats. This is usually done by mounting the front of the links in the higher holes on the left side. With the use of a lift bar, this effect could be reversed, causing rear steer to the right.
8. PROPER GEARING/REAREND PROBLEMS
A car that is sluggish off the corner and tends to be a rocket at the end of the straightaway may be geared incorrectly. The place to accelerate quickly is not at the end, but at the beginning of the straightaway for several reasons.
Using a lower gear to get off the corners will produce more increase in mph in the first half of the straight than a higher gear will produce in the last half of the straight. We can pass much better and more safely coming off a corner than on entry. Diving in under a competitor can have some very negative consequences.
We must properly maintain our rearend. The wrong tension springs in a locker rearend or springs that have lost their tension will cause all kinds of setup problems as the wheels lock up erratically. A mid-season inspection and maintenance on our rearend will help us avoid mid- to late-season problems.
Sliders such as these must...
Sliders such as these must be inspected and maintained often to prevent corrosion. If these parts do not move freely, then the setup will be off and the handling will be hard to nail down.
All race cars need maintenance. Ball joints, Heim joints, sliders, brakes, the cooling system, the fuel system, and any other system that we rely on must be inspected. Dirt cars are especially prone to corrosion problems due to the fact that the cars are constantly washed down and cleaned after every event.
The coilover eliminators must be maintained, sometimes on a week-to-week basis. Shocks must be inspected often. You should take them off and cycle them by hand through the complete range of motion. Broken valving and air intrusion can be detected by doing this, and handling problems associated with bad shocks can be avoided.
Remember that you need to...
Remember that you need to run the correct stagger based on the radius of your track. Problems with tightness in the middle (when using a spool rear differential) or tightness off the corners (when using a locker differential) can be caused by insufficient stagger. The formula shown is for determining the correct stagger.
10. DRIVING STYLE
Last, but certainly not least, is a short discussion about driving. Many drivers are "never wrong," so they think. And trying to convince a parent that their little darling isn't perfect can be very frustrating for a consultant or crew chief. But sometimes getting ahead is only a matter of helping the driver to understand the track. The best driving line might be in a different place from what feels fast to the driver. The stopwatch and passing performance depend on driving the correct line, not what feels fast to the driver.