Scottvoight's NASCAR Blog

February 13, 2010

Tight and Loose, what are they?

Filed under: NASCAR News and Views — Scott Voight @ 8:54 am

During the Daytona 500 several drivers were complaining their cars were tight. In this condition the front wheels lose grip with the road. This causes the car to thrust the front of the car toward the outside wall. If a driver rounds a left hand curve to fast the car will tend to take the curve very wide and drift toward the right this is called pushing in NASCAR. To keep from crashing you have to take your foot off the gas and slow the car down to turning your wheels to the left to regain traction. 

Depending on how bad the loose condition is there are several ways to correct it. The first thing a crew chief will do is to adjust the tire pressure. If the right side of the car has less tire pressure than the left, the car will turn left easier. Because the car body rolls over onto the tire in the curve and puts more of the cars weight on that side, using inertia to help steer the car. The tires themselves will flex and act like a shock absorber works in your car.

Another way is to change the load (the cars weight when it rolls over) on the spring in the rear of the car, on the left side. It is like walking on stilts if one stilt is shorter than the other your body will lean to the shorter side and your body weight will be shifted more to that side. So by compressing the spring in the car, the car body leans over to one side more and helps the car turn. This is called loosening up or freeing up the car.

When the car is experiencing a major tight condition the crew will add a spring rubber to the spring on the opposite side of the direction of the curve. Another  words, if a driver is having trouble turning left, a spring rubber will be added to the right rear spring. A spring rubber is a rubber doughnut that is about 3 inches thick. It is put between the coils of a spring preventing it from compressing. If you took out the spring in your pen and put a tooth pick between one of the coils when you push down on the spring it will not compress as far down as it would without it. This forces the car body to roll to the left better by holding the right side up higher, thus helping the car to steer to the left.

There are other ways to adjust the car for a tight condition during practice, but these are the two most common ways to change the tight condition during a pit stop and the ones you will hear the announcers talk about the most.

A loose condition is something entirely different and concerns the rear of the car. This is where the rear tires lose grip with the road in a curve and want to slide toward the outside wall. This is like driving your car into a left hand curve with gravel on the road. The rear tires of the car lose traction with the road, because of the gravel, and it slides to the right. To correct the slide you have to steer the car to the right to catch (straighten the direction of the car) the car and resume going in a straight line.

Loose is almost the opposite of tight so if you do the opposite things described for a tight condition it will fix a loose condition.

Remember, when you were young and went sledding, if you put weight on one side of the sled it will go that direction. The body of the car is similar to the body on the sled. The more weight that is added to one tire or corner of the car inertia will cause the car will go in that direction too.

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