Tech Q&A: Paul Andrews

February 8, 2001
6:07 PM EST (2307 GMT)

Q: Using a scanner, I've heard the crews say that they are going to do a tire sheet and plug check at the end of a practice run. What exactly are the crews checking for and what roles do they play in getting the car set up for the race? Jeremy Harvey Bolivar, Mo.

A: Usually, a tire sheet and plug check could be done in qualifying or practice trim, but usually most effective in race trim. When you're preparing for the race, you want your tire sheet to show the tires' temperature front to rear, left to right and across the tire. That tells you what kind of camber wear you have. If your car is tight or loose, you should usually hear that on the scanners also, and the tire sheet can tell you whether your car is tight or loose. The plug check is simply, when you shut the motor off at the end of the straightaway without letting it decelerate, then you look at the plugs to see if the motor can be any leaner or richer for fuel mileage or whatever it is that you're looking for.

Q: I know that each track set up for the cars is different, Do the teams have a different carburetor for each track or do they use the same one each time and re-jet it for the different tracks? Allen Dendy Jr. Prineville,Ore.

A: Usually, it's the same style of carburetor. It may not be the exact same carburetor, but it will at least be the same style. It's re-jetted for every track and every weather condition.

Q: Explain the reaction of roll center by changing the angle of the panhard bar. I have discovered that by increasing the angle of the panhard bar, we reduce the amount of chassis roll on the right side. Explain why. Thank you DBH David Harrison Leawood, Kansas

A: When you raise the panhard bar it raises the roll center, and makes the car roll less. When you lower it, it lowers the roll center. The car tends to roll further with the track bar lower as it rolls from left side to right side.

Q: With all of the talk about fuel mileage lately, why don't the Winston Cup cars use fuel gauges? Lee Utterback Gaithersburg, Md

A: Well, it's not allowed. I wish we could use one, or at least some type of light or warning device that lets us know that we've reached a certain point. The best thing we've got is a fuel pressure gauge, which is located at the carburetor. So, when you lose fuel pressure, it's usually too late then.