ESPN's Andy Petree answers your questions

Former championship crew chief Andy Petree has the answers to your questions about air pressure, engine rebuilds and more in this week's mailbag.

Updated: November 5, 2008, 3:49 PM ET
ESPN.com

NASCAR Icons readers filled the mailbag with questions for ESPN analyst Andy Petree and he responded to some of the best ones below.

Andy Petree
Phil Cavali/ESPNAndy Petree agrees that rubbin' is racin', but David Gilliland's incident with Juan Pablo Montoya at Texas is another matter.
Petree is a former crew chief, driver and crew member on NASCAR teams, most notably as Dale Earnhardt's crew chief with Richard Childress Racing for back-to-back Cup titles in 1993 and 1994.

Petree, who joined ESPN in 2007, also owned Andy Petree Racing and he worked with such drivers as Ken Schrader, Kenny Wallace, Joe Nemechek, the late Bobby Hamilton and Greg Biffle.

Here are your questions and Petree' answers:

Do you agree with NASCAR parking the David Gilliland's No. 38 car Sunday? Personally, I absolutely agree it was the right thing to do, I am even toying with the fact he should also be parked at Phoenix. There is NO excuse for putting a driver in the wall like that -- even if that driver is the sometimes hot-headed Juan Pablo Montoya. Drivers give each other a bump from time to time, which is OK. Rubbin's racin', right?
Lisa,
England

Petree:
OK, rubbin's racing, yes. Bumping around and that kind of thing I agree you absolutely, positively never should do what he did, which was an intentional move and he crashed him in a straightaway at a high-speed race track.

NASCAR did the right thing by parking him. I think that he should have received more penalty. And I'm actually surprised that he'll even get to race these next two races. But if it was up to me he wouldn't.

Do the crew chiefs remove or rebuild the engines after a 500 mile race?
Sam Rodgers
Travelers Rest, S.C.

Petree: Oh, yeah, absolutely. They do an extensive rebuild every race. They'll take it all the way down to the bare block, every single piece, inspect every part. And there are components in the engine that have cycle limits. The crankshaft has a certain amount of cycles that it will run before they change it. And they calculate that. There's a formula they use, how many miles it has run so then they figure all the cycles that are on that particular part, whether it's connecting rods or crankshafts.

They'll change the valves every race, they'll change the valve springs every race, they'll change the pistons every race, obviously all the gaskets and all that stuff. But they do an extensive rebuild on that thing every time it's run.

When a driver complains about lack of grip, you always hear the crew chief say they will adjust the air pressure in their tires. To get more grip, do they decrease the air pressure? I think they must, but I never hear the analyst on TV mention which way the air pressure is being adjusted.
Raymond Paul
Lincoln, Calif.

Petree:
Well, here's the funny thing: If just going one certain way on air pressure just kept giving you more and more grip, they would all wind up at the lowest or highest pressure, whatever it took to get the most grip. It's really about the balance of the car, OK.

There are limits on air pressure on how far you can go up or down. Goodyear gives you parameters for that. And the teams pretty much stay in that and as a matter of fact they even require you to stay at a certain pressure in the right front. But what they're trying to do when they change air pressure is, let's say the car's loose, they're going to try to do some things with air pressure that are going to shift that balance to help give a little grip to the rear and possibly then take a little away from the front. It's always a balance that you're trying to find. And once the car is balanced that is really where you're going to find the maximum grip.

I am a huge Jeff Gordon fan and I can't help but wonder, how can he be fast enough to lead practice and win the pole but then fall fast during the race. What exactly happens to the car?
Tommy Briggs,
Clinton, Miss.

Petree:
I'm a big Jeff Gordon fan also. I can't stress enough just how competitive this sport is. And yeah, he was very fast in qualifying. But they have had some problems with making their car good for the race and then adjusting during the race to keep it good.

The thing is it's just so competitive and it's not easy. It tells you how hard it is to compete at this level. Jeff had a good run, he finished second last week. But he just didn't have the dominant car.

What happens is, programs like Carl Edwards they have a great program right now and they're really hitting on something. The sun never shines on the same person all the time and it's going to change. It's going to happen for Jeff. It's a shame that it hasn't happened already this year. I know he's winless, but all hope is not lost. He's still as good of a race car driver as he ever was and he will win more races when they finally hit on the right combination.

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