Racing Counterclockwise

Cecil's Columns/Staff Reports
1

–Note to JillGat: I don’t know if this column is online…I couldnt find it, at least!–

Anyhoo, the technical, physical reason (I ain’t gonna vouch for any metaphysical or “traditional” reasons) that auto races are run counterclocwise is torque. When a spinning object (i.e. the crankshaft) is pulled in a given direction, a torque of great force is created perpendicular to the movement. When the crankshaft is turned left, as in an auto race, the crankshaft and anything attached to it (garish paint job, redneck, etc.) is pushed down into the road. If races were run clockwise, above items would be pulled up and off the road, resulting in muchos problemos.

2

Really? The races at Road Atlanta are run clockwise and the track has been having races there for . . .hmm, nearly 30 years.

I’ve attended more than a few of these races, and I do not recall torque being cited excessively as the cause of engine failure.

your humble TubaDiva

3

So, Ennius, you also think that right handed screw threads are due to torque, rather than to most people being right-handed? (See related thread somewhere [in GQ?].)

4

And yet another person is completely confused by the “torque vector” fiction.

John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams

5

Hey, guys, take it up with my physics teacher. He told me this, and did a great demonstration using a spinning bicycle wheel. I’m not saying this is the only reason races are run counterclockwise (and I guess the spoilers could counteract the torque), but it’s a reason that might have had some factor in the decision at most places to go counterclockwise. I’m not gonna vouch for Georgians; they elected Newt for years…

6

I’ve always thought that (most) oval car races are counterclockwise because horse races are counterclockwise. Horses don’t generate much torque.

7

The “centrifugal force” is perpendicular to the movement of the tires, so gyroscopic effects don’t come into play; and the tires are the only part of the car that have enough combined RPM’s and moment of inertia for gyroscopic effects to be meaningful.

Car races are counterclockwise because horse races are counterclockwise.

John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams

8

I’m not talking about centrifugal " force," JWK. But at least you tried to give me a scientific reason for why I may have been misguided. I still hold that the spinning crankshaft (btw, moment of inertia has nothing to do with this) can generate enough torque to create problems, but no one seems to be willing/able to refute this scientifically…if you can, I’ll freely admit my error!

9

Ennius
Member posted 08-21-1999 01:31 PM

“Anyhoo, the technical, physical reason (I ain't gonna vouch for any metaphysical or "traditional" reasons) that auto races are run counterclocwise is torque.”

  If you’re saying that torque is an explanation in addition to ones of tradition, that’s a possibility, but not for the reasons you give.

      “When a spinning object (i.e. the crankshaft) is pulled in a given direction, a torque of great force is created perpendicular to the movement.”

      “Great force” is kinda subjective, isn’t it?

     “When the crankshaft is turned left, as in an auto race, the crankshaft and anything attached to it (garish paint job, redneck, etc.) is pushed down into the road.“

    I don’t think you understand what torque is. Torque applies to angular motion, not lateral motion. If there is significant torque on the vehicle (which is a possibility), then it would make the car roll, not levitate or sink. Half of the car would be pushed into the road, and half would be lifted. If this effect is too large, the car will roll over. But the direction of the track determines **which way** the car will roll over; it doesn’t change whether or not the car **will** roll over.

Ennius
Member posted 08-24-1999 11:11 AM

  “I still hold that the spinning crankshaft (btw, moment of inertia has nothing to do with this)”

  Torque = angular acceleration times moment of inertia. While the “centrifugal force” isn’t relevant, the moment of inertia is. Moment of inertia is a variable which is combination of how much mass there is and how far from the center it is. The farther from the center, the farther it has to go each revolution, and therefore the more torque required to increase the RPM.

 "can generate enough torque to create problems, but no one seems to be willing/able to refute this scientifically...if you can, I'll freely admit my error!"

 The axis of the crankshaft is in the direction of travel of the car (lateral axis, I believe). The axis of revolution (that is, the car going around the track) is vertical. Any cross product would lie along the other axis; that is, the axis running from the left side of the car to the right. Therefore, if the car rolls, it's going to roll end over end. While it is possible for cars to roll like that, it takes a lot of energy. I really don't see a crankshaft, which really doesn't have a particularly large moment of inertia, creating that sort of torque. And if a crankshaft can do it, wheels should be able to do it much more easily, since wheel torgue would make the car roll along its lateral axis. Is there a significant difference in percentage of cars that roll end over end in clockwise vs. counterclockwise races?

-Ryan
" ‘Ideas on Earth were badges of friendship or enmity. Their content did not matter.’ " -Kurt Vonnegut, * Breakfast of Champions *

10

One might also point out that crankshafts can go side to side in a transverse mount engine, and we don’t see them separating those cars in SCCA races according to the direction of crankshaft rotation.

I think that Ennius made two errors in his initial post. First, the thinking is two dimensional, but physics is three-dimensional (thus the difference between lifting off the road and torquing around the axis). Second, even if the thought were correct, in the absence of evidence to support the theory, stating it as if it were fact makes for bad science.

Further reflection on certain points would make one think twice about the assumptions in the statement. 1) Oval racing is generally an American invention; in the rest of the world they tend to prefer ‘road’ racing, where the turns are both left AND right. 2) In Britain, among other places, racing is usually done clockwise around the track, just as horse races in Britain are run. 3) You don’t see passenger cars lifting off into the air when cornering around a right turn too fast (the equivalent of the clockwise oval). Although, I DO think it would be fun if we could jump over stopped traffic by doing a right donut. :slight_smile:

11

As a further post on this, someone might want to check out the truth of this:

I have a racing friend who indicates that racing in America went clockwise at first, but that with the advent of the passenger car with a left-sided steering wheel, it was determined to go counter-clockwise to protect the driver from the outer wall of the track better.

12

Okay, I’ll admit that the absence of evidence is a bit damning–but let us remember, absence of evidence is not evidence of absence! Regardless of whether this phenomenon is actually observed, it is certainly a distinct possibility–if, as one of you who teem pointed out, you simply replace every instance of “crankshaft” in my posts with “wheels.” It is the wheels that create the angular momentum and the gyroscopic effect which I discussed. Bearing this in mind, I invite any Teemster (hmmm…) to try this simple experiment at home: take one bicycle wheel. Attach it to a longish axle. Hold said axle in front of you so that you are looking at the side of the wheel. Spin the wheel until it is rotating very quickly. Note now that you can do many fun things with your homemade gyroscope, such as balance it on the tip of your finger (as long as you don’t get dizzy from the precession), etc. Ignore these. Instead, pull the whole contraption to the right, simulating a car making a right-hand turn. Note that the wheel is yanked (here’s my beloved torque at work) up as well as to the right. Now pull the wheel left. Note the reverse. Does this phenomenon have any real effect on an automoblie? I dunno, and, judging from the responses to this post, probably not. But wouldn’t it be cool if this did in fact happen? And isn’t that more important than some silly fact like it doesn’t happen? But trust me on the bicycle wheel.

13

Check out this link:
www.nascar.com/news/1999news/April/14/00986209.html

See the last question on the page. If a governing body as large and prestigious as NASCAR doesn’t have a difinitive answer as to why THEIR OWN RACES are run counterclockwise, I’m not sure who would.

14

Istarted a similar question in the General forum, Why run counterclockwise.
I have nothing much to add here, except that the torque thing can be real.
In one of the European countries with hills, they started running buses with a flywheel to store energy (from braking, slowing). I can’t even tell how the heavy flywheel was placed. In any case they didn’t get it to work the way they had set it up. Every time the bus turned a corner, it fell on its side.
I have no source to quote, because I heard this some 20 years ago.

15

<sigh>

The wheel is not pulled ‘up and to the right’, it is torqued, that is, forced around the third axis, in this case the axis running parallel to the ground and perpendicular to the wheel’s axel. ‘Up and right’ is also ‘down and left’, which is the precise point the teeming millions have been trying to make for the last 10 posts or so. :wink:

But just so you don’t feel too bad about failure to understand conservation of angular momentum, you should know that there CAN BE torque difficulties from certain arrangements of drive wheels and crankshafts. I am not sure I understand it all, but apparently certain front-wheel drive vehicles do suffer from a torquing effect that can affect steerability, although I believe the direction of the turn is irrelevant.

And should you want to study angular momentum further, check out any first-year college physics text; there are some really interesting things you can do with spinning disks. :slight_smile:

16

SCCA’s no help either; I’ve been asking this question for quite some time, going back to the AOL days. Folks keep asking and we keep not finding out the answer. Seems nobody knows.

Ditto the flags issue as well; I’ve had a Mailbag question sitting on my desk for over a year because nobody in any racing organization has been able to tell me how the system of flagging evolved. Why do we end with checkered flags . . . how did all the various combinations of colors and etc. for all the other flagging situations get started?

There’s quite a few theories, but no real proof.

I’m continuing to work at it, though.

your humble TubaDiva/SDStaffDiv
for the Straight Dope

17

To DSYoungESQ:

I think you may not have actually tried this. I have. Let me assure you that, if you do as I have prescribed, the wheel will be torqued up when you try to pull it right, and torqued down when you try to turn it left. So the direction in which the bicycle wheel (as I said, I’m leaving cars alone for now, seeing as how I was apparently wrong…) is torqued along that third axis (btw, how can it be both parallel to the ground and perpendicular to the axle? The axle is parallel to the ground) is reliant upon which way you try to turn it. Try it, it works. And is Biancoli’s Physics good enough for you? It was my textbook last year…

18

Here’s one way to picture it in relation to cars. Let’s think about an airplane. It can turn in 3 dimensions. Left-to-right is called “yaw”. Nose-over-tail is “pitch”. and wing over wing is “roll”.
If we put some big wheels on it spinning fast like car tires, they are spinning around the “pitch” axis. If we try to turn the plane on the “yaw” axis, as a race car would. The gyroscopic effect, will cause the plane to try to “roll”. The same thing happens with the car, or the bicycle wheel. If it is spinning on axis 1. and we try to turn it around axis 2. it will try to turn around axis 3. So the car would try to roll whether it was a counter-clockwise track or clockwiset. It would just roll in the oposite direction.

19

The rotational torque of a car in a race is negligible. Think about it; at how many RPM’s is the car rotating? One or two? Heck, mount a car on a ball-bearing turntable, and I’ll push it faster than that!

John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams

20

Yes, I agree, the torque is probably very small.