Are NASCAR vehicles weighted to turn left?

Factual Questions
1

Mrs. RickJay and I were out to dinner last night and a NASCAR event was on the big screen TV. I watched in fascination as the cars just drove around in a circle, eternally turning left. It’s not very interesting but it’s certainly hypnotic.

I was curious; since all NASCAR events are like this - circles and ovals, always turning left - are the cars designed with this in mind? Since they don’t ever turn the other way, do they, say, add extra weight to the left side of the car, or put bigger tired on the right side? What about the steering mechanism itself?
Or is this prohibited by the rules?

2

This would probably be better for GQ but since it’s here I’m going to post what I remember from watching races. I think they actually DO set the cars up to turn left, but it’s not from weight, it’s because of the way they set the shocks up. IIRC they make the shocks on the left side of the car tighter(less air?) and the shocks on the right softer.

Take that for what it’s worth. (Nothing.)

3

I don’t know why I thought this was in MPSIMS. Probably because I, like all NASCAR fans, am drunk on Sunday.

4

Teams don’t have a lot of flexibility when it comes to weight distribution, but they have some. They are limited as to how much weight can be left of the centerline of the car (60%, I believe.)

The fueling system fills from the left side for this purpose, which is why cars used on the road course at Watkins Glen fuel from the right side (as it’s primarily a right-hand course.) Lead ballast is also used to control weight placement.

Tires are of uniform size and weight, according to NASCAR rules, although teams can change air pressure.

There is some left-side bias in the suspension geometry, primarily in camber (amount of tilt of the front tires) and in toe (angle of tire relative to straight ahead.) Front tires are tilted to allow for a larger contact patch in the corners, and the toe can be adjusted in or out to aid the car’s turning ability. This is why commentators will often refer to the car being “knocked out of toe” after brushing the wall, as the tie rod connecting the hub to the steering can become bent or moved, changing the amount of toe and therefore the effectiveness of the steering.

5

Except this week’s race was a Saturday night short track special, so there goes your theory. :smiley:

6

I saw an aerial view of a NASCAR track. The bowl was full of whitish-grey haze. If you had been at the track instead of watching it on TV, I’d suggest that there was another reason why it was ‘hypnotic’. :smiley:

7

Hey - I’ve actually driven a NASCAR, at Texas Motor Speedway. They are indeed setup to turn left easily, but I don’t know the details of what it takes to do that. The right rear corner of the car is higher than the front left, that much I recall. When you’re driving on the straightaway, it takes rightwards pressure on the steering wheel to keep it going straight. When you get to the corner, it feels like a very natural thing for the car to do, and just slides right down into the corner very easily.

8

Cool, I might be right!

9

The NASCAR rule book says cars must have no more that 56% left side weight. They use lead bars that are placed in the left and right side frame rails to set this weight. A typical Nextel Cup car weighs about 2900 pounds without the weight, it must weight 3400 pounds when it crosses the scales.

The biggest help in making the cars turn left is called tire stagger. That is the difference between the circumference of the right and left side tires. The tires supplied by Goodyear are made with the left side tires smaller than the right side. Fine adjustments are made using air pressure. An example of this would be if you roll a paper cup on it’s side. The smaller end turns sharper that the bigger end. A typical Nextel Cup race car has about 40 items that can be adjusted in some form to help the handling of the car. The better teams have done a better job of figuring out which adjustments need to be made to win the race.

And a hardy congrats to Kasey Kahne, a local boy done good, he won his first Nextel cup race last night. He is from Enumclaw, that is about 20 miles from me.

10

Thanks for correcting me on the weight percentage. After I posted that, 60% sounded too high, but I couldn’t remember the right number.

Are you sure tires are still staggered like that? I know they were in the bias-ply days, but it was my understanding that they changed that when Goodyear switched to radials.

11

As a related question, is there any special reason why stock car tracks are simple ovals instead of more complex Formula-1 type affairs?

(The cars we race now couldn’t handle it, but the cars adapt to the tracks. Back in the 1930s maybe it could have been done.)

12

NASCAR runs two road courses per year, so its not that they can’t, but they certainly don’t have the grace that Formula 1 or even LeMans style sports cars do. And the budgets of NASCAR teams allow them to build purpose built “road course” cars which are internally much different than the cars they run on the ovals, though they look the same on the outside.

Why? Tradition. Classic “stock car” racing (as in real off the assembly line cars with tricked out engines) in America was typically done on small oval tracks, most likely on a track originally built for horse racing. NASCAR grew up out of this tradition. Road racing was done, originally on real roads as in Europe, but typically the cars in these races were generally sport cars. For a variety of reasons, this side of the sport never could get itself together into a dominate organization like Formula 1 in Europe or NASCAR over here.

13

At each race Goodyear bring two different tires, one for the left and one for the right side. The left side tires have a smaller circumference than the rights and are made with a softer rubber, the idea is that all 4 tires will wear at the same rate during a race. Jayski.com lists the tires info for each race, scroll down to the Goodyear notes. Goodyear makes about 30 different tires that are used throughout the season in NASCAR’s 3 top divisions. The tire combination used at Richmond is also used at Phoenix and New Hampshire. The size and type of track determines which tires will be used.

14

I worked on the pit crew of a bomber class race car last year. Tires had to be all the same diameter, but we set the tire pressures from right front going clockwise to 40,32,28 and 18 psi.

15

Are any NASCAR races ever run clockwise?

Wouldn’t it be cool if the NASCAR commissioner (or whatever he’s called) showed up at Daytona and said “We’re going to run the other way around this year, just for the hell of it!”? :cool:

16

The road courses are run clockwise.

17

Isn’t this because of the banking of the track itself? I have driven a street car on a NASCAR track (Lowes Motor Speedway in Charlotte) and it does the same thing.

18

That’s a good question. I know the back straightaway is banked. The front is flat IIRC, but it’s not really straight - it’s three segments that you just round out with a big leftward arc, and I think the car went around that arc pretty much by itself.

19

The banking is also a reason for “self cleaning accidents” in many race tracks. The crash happens, and the cars slide “down” the hill, off the racing grooves. It doesn’t always happen this way, but many tracks have this tendancy.

Banking does interesting things, this past winter, driving south on the Everett Turpike out of Manchester NH, we were in a snowstorm, traveling about 10MPH. Normally, the banking of the turn works wonderfully. The cars stick to the road, turn nicely, and are capable of negotiating the turn at VERY high speed (though I tend to keep it near the posted limits). This day, however, the banking worked against us. Periodically, the car in front of me would begin sliding down the banking, and as I reached that same spot, I’d slide down the hill. It was very humorous in the situation, even though it was frustrating due to the delay in getting to work. I was genuinely afraid of sliding all the way off the roadway, even though I was WAY under the speed limits.

I’ve also driven at NHIS (New Hampshire International Speedway) in Louden NH, and found my VW Golf turned very nicely in the banked turns. Amazingly comfortable at 70+. ( I was a worker, returning to the garage area, during a track school event, so I couldn’t/wouldn’t push it faster than that).

If you watch a race, and they go through some of the technology segments, you will see multiple things that contribute to a tendancy of the cars to “turn left”. Wheel camber, toe settings, spring and shock settings, wedge (I still don’t understand that 100%), weight distribution (mentioned above), air pressure, etc…

Most fast tracks have banked straightaways, they help with entering and exiting the turns. If the car is already “leaning” that way as you exit/enter, you get less weight shifting, which can upset traction. This is also influnced by using the brakes while using the gas to shift weight to the desired wheel(s). You will also notice that they rarely go straight on a straightaway, as you generally move towards the wall coming off of the corner, and away from it heading into the corner. Check out the rubber trails next time you see a straight section.