Doesn't matter whether you are speeding down a highway, driving in the rain or flying around a beach. Without the right kind of tyres you will go more off track than pay per view Sasha Grey.
For a dirt track you need traction more than you need power or the blessing of the Pope. For traction on dirt your worst enemy are street tyres. The wheels spun pointlessly all the time.
You need knobby tyres. You need narrower tyres that can easily cut through the sand like the way that 1NZFE powered Corolla did. And you need lower pressure to keep the tyre walls soft and more pliable. I released the pressure, wet the sand down around the tyres and we just drove out. And last but not least, if you can lower the weight of your car you have a better handling vehicle regardless of power.
If you can, have uber-thin Kate Moss to drive your car. How that woman always remains so thin is a mystery other women worry about. Taping the handbrake button - it's a trick used by experienced dirt autocross drivers. The handbrake comes in handy when making tight turns. Rear wheels lock up, the rear slides around. They tape the button so that when they let it go, the lever falls down and there is not risk of the lever sticking and causing you to lose valuable time.
Skip to main content. Shift Garage. In this condition the tire with the most weight load gets the most bite. Or you could think of this as the tire with the least weight gets the least amount of bite.
A standard transmission clutch is a good similarity to this truism. Try this test at home and you will see how this works. On a level road with the engine revs at about RPM, gently let out on the clutch until the car just starts to roll, but you still have a lot of slippage in the clutch.
Now, without changing the clutch load, press the throttle to the floor. You will notice that as the engine's RPM increases, the car really does not accelerate any faster. However, if you change the clutch load, the car will accelerate very differently. All is going to be lost once that LF comes up as we accelerate. 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. The rear geometry needs to be arranged so that minimal rear steer takes place in order to keep the car going straight ahead, much like an asphalt car.
With all four tires on the ground, a high amount of LR weight can be put in the car to provide improved traction off the corners. The car will turn in well and drive through the middle because of the balanced setup causing the LF tire to work to turn the car. Some racers have even been known to run a stiffer RR spring when conditions warrant less RR chassis travel. Mid-Point Traction As the track begins to dry out through the qualifying heat races, a team must observe the surface conditions during the heats just before they race.
If the track is going black-slick, the setup may need to change as well as the tire selection. These slicker track conditions can cause excess heat buildup in the tires, and more siping is required to help cool the rubber. The RR can be a little softer to promote traction off the corners, but that will produce more chassis roll at the rear and unload the LF tire.
The LF is not going to hike up, but it will become less loaded. So the crossweight, or LR weight, will need to come down so that the balance of weight between the rear tires doesn't become uneven. This prevents a condition in which the LR as well as the RF ends up with a high weight while the RR supports very little weight.
Less equally loaded rear tires mean less traction off the corners. Dry, Slick Conditions As the track dries out further and the surface becomes dry and slick, drastic measures must be taken. We need more weight transfer, a sideways attitude of the car relative to the direction of travel, and a rear geometry that will help overcome the tendency of the car to push on entry and through the middle.
We would soften the right-side springs to help the front turn and the rear to promote traction off the corners. The track bar must be mounted on the left side of the chassis and angled to a greater degree left side higher to help pin the RR tire. The greater angle of the bar also causes the chassis to hike up in the rear, which produces rear steer, the degree dependent on the angle of the linkage bars in the rear suspension.
While all of this is happening, we need to make sure that the LF doesn't lift too high off the ground. Recall the aero discussion about keeping the nose close to the ground to keep the downforce in effect.
The LF tire can be floating somewhat, but if it is not well off the ground allowing air to get under the front end, the aero will still work. A considerable amount of rear steer steering to the right, usually utilizing the LR coming forward may promote the aero effect, which helps keep the car down on the inside of the track in the corners.
This comes from the flat sides of the car striking the air, similar to the effect of a wing on a Sprint Car. Once the car has moved through the middle and it is time to accelerate off the corner, we need the LR to squat and the tire to come back into a more straightforward position for better exit performance.
Most racers now agree that all rear steer should be accomplished through LR wheel movement. If the RR wheel moves excessively, the feel is inconsistent to the driver because the RR is normally the dominant driven wheel off the corners. The movement of the LR wheel is much less offensive in nature.
Conclusion In a particular event, we may experience a wide variety of track surface conditions that require us to adjust our setup. A team that makes an educated guess about the changes to make has a better chance of winning than a team that makes very few changes. It takes a lot of work to make these changes, and we must think correctly in order to make the best changes. In the long run, if we expect a fighting chance at winning, we must learn to react.
After all, the top teams have definitely learned, they make the adjustments, and, best of all, they win often. Next month we will detail how to make those adjustments. Close Ad. The Future. Join MotorTrend. Bob Bolles writer Chuck Gonzalez photographer.
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