Grooved Axles

[Mojo Racing]

VK... Did you send a car in to this race?

If you did... and it is a SS or a BASX... let me know... I will overnight one of mine out there.... Maybe John will do a challenge race for us...

 

[Vitamin K]

VK... Did you send a car in to this race?

If you did... and it is a SS or a BASX... let me know... I will overnight one of mine out there.... Maybe John will do a challenge race for us...

Hah, nope, sorry. Prefer that you'd just stick to the original discussion though, and read the several links provided that explain why surface contact area is not a component of friction.

 

[Mojo Racing]

Yeah... thought so.

Let me know when you change your mind...

 

[Obsessedderbydad]

For someone that knows so much about PWD racing and gives so much advise, you're sure scared to race. With all this knowledge you're passing on to ppl I'd think you were the guy to beat. You're as bad as Derby worx not wanting to race John.

 

[Vitamin K]

Yeah... thought so. Let me know when you change your mind...

For someone that knows so much about PWD racing and gives so much advise, you're sure scared to race. With all this knowledge you're passing on to ppl I'd think you were the guy to beat. You're as bad as Derby worx not wanting to race John.

Guys, seriously? Because I'm not currently racing in the leagues means I can't hold forth on basic scientific principles? For which I (and other folks) have linked supporting proof?

Just because your hypothetical car might beat my hypothetical car still doesn't prove that surface contact area is a component of friction. /images/boards/smilies/smile.gif

 

[OPARENNEN]

Some of these posts are a bit too caustic for me, unless it is meant in good fun. Sometimes I can't tell.

 

[LightninBoy]

I'll quote from 5Kids' website:

In reality, every axle and every bore has imperfections..... if you assumed that there were no imperfections then you would come to the result that grooves do not help in a pwd race... by having grooved axles you minimize your chances of riding on a bad part of the wheel bore or axle. Quite simply you are riding on less bore/axle area so you increase your odds of having a faster car by eliminating possible bad spots. Additionally having a center grooved axle makes the wheel ride on the two ends of the bore stabilizing the wheel. Imagine a high spot in the middle of the bore either on the axle or the wheel bore, the wheel would wobble back and forth creating a teeter-tooter effect making for an unstable wiggly car..... bad, bad, bad... BSA axles are horrible, they aren't round and they aren't concentric from end to end. Adding a groove removes all of the bad material in the middle and forces your wheel to ride on the two outer points, stabilizing the car. If legal in your race buy quality grooved axles..... not multi-grooved either, single center groove.

This thread should have ended here.

 

[dpatrick911]

The frictional force is proportional to the real, not apparent, area of contact, and the real area of contact is proportional to the load. Therefore the area cancels and the frictional force is proportional to the load. Real contact area is "atomic scale roughness". If you were to look at any surface under a powerful microscope it would not be smooth. In fact it would look much like a mountain range with high peaks and valleys. When we place two surfaces in contact with one another, there are places where the peaks are touching. At these points the material "cold welds" together. It takes a force to break these welds apart. These welds are the reason for friction. As you increase the load these peaks deform and spread so the area of contact increases. The force divided by the real area is roughly the yield pressure, which is a material property and roughly constant, so you end up with the real area of contact roughly proportional to the load.

The car still weights 5oz. Grooved axles don't make the car lighter. That 5oz. is just applied to a smaller surface area. At least that is what we see, it makes sense from a "what I can see and touch standpoint". However as the description above explains... the peaks we would see under a microscope on the axles would deform and become "shorter" or spread out, because of the increase load over the smaller surface area just prior to the surfaces contacting on another. Once the surface make contact the breakdown of those peaks starts until the load is supported. Mathmatically the contact area would remain the same as non grooved axles for the reasons described above. The reason grooved axles are faster likely has more to do with surface imperfections over a larger surface area than anything. Imperfections not visible to the naked eye.

 

[Obsessedderbydad]

It's ok VK. The guy who challenged you hasn't league raced either. For all we know he's blowin smoke.

 

[Crash Enburn]

Mathematically, they shouldn't reduce friction, since surface area contact isn't a factor in that equation. However, since they reduce the actual area of contact, there's less space for surface irregularities to factor in.

The mathematical standard formula for friction:
F[sub]r[/sub] = μN

F[sub]r [/sub]is the Force of resistance (the friction)
μ is the coefficient of friction.
N is the normal or perpendicular force pushing the two objects together (like gravity's pull on the body).

You will note that area is NOT included in this calculation. Less area or more, the amount of friction is the same.

Another function of the groove is that it happens to sit right where any bore scratching may have occurred when inserting a bent axle.

 

[Mister B Racing]

Gosh... I knew I should have stayed away from the PWD forum a while longer. While you guys argue about friction and gravity or what ever, I'm going racing.

Racing these cars is all about overcoming friction and gravity. I don't know or care how much or little friction there is between axles and wheels. That's why we prep everything, that's why we polish and wax and buff everything!

All together now! Polish, wax, and buff! Lets race!

 

[BlewBYu]

LOL! Didn't know I was creating a firestorm of controversy with my original question! The one thing that I am taking from this is that grooved axles ARE faster than non-grooved ones based upon several factors. I'm OK with that, as I have my answer.

 

[HMH Racing]

Only thing I would add is "properly grooved axles" are faster, other than that I think you got it /images/boards/smilies/smile.gif

 

[Obsessedderbydad]

Mathematically, they shouldn't reduce friction, since surface area contact isn't a factor in that equation. However, since they reduce the actual area of contact, there's less space for surface irregularities to factor in.

The mathematical standard formula for friction:
F[sub]r[/sub] = μN

F[sub]r [/sub]is the Force of resistance (the friction)
μ is the coefficient of friction.
N is the normal or perpendicular force pushing the two objects together (like gravity's pull on the body).

You will note that area is NOT included in this calculation. Less area or more, the amount of friction is the same.

Another function of the groove is that it happens to sit right where any bore scratching may have occurred when inserting a bent axle.

That's only one of many many friction formulas

 

[Bullet]

Personally, I just think the return of Mr. Chips has everyone fired up! /images/boards/smilies/tongue.gif I will play into his forum persona on this one....lol

Good discussion for everyone though, gets the brain thinking 'bout stuff!

 

[Quicktimederby]

Funny how you can know everything about everything, and still cat build a car to compete. I get lost a few minutes of reading that big old discourse. I'll just keep being stupid, and using proven methods that work better for me.

 

[dpatrick911]

The thing about this entire post and the pages and pages of replies that I find amusing is, we are all basically saying the same thing. Grooved Axles do indeed seem to be faster! The hows and whys are of little concern. Unless you are interested in that stuff. If you are interested, you have basically had a crash course about friction and the physics laws that explain the hows and whys of friction. If you don't care and just want to go fast. Awesome! Go for it. I don't really care about how a diesel engine works either. But I do care that my order from DD4H, in the back of an 18 wheeler, coming from Utah to Michigan, gets to my door before race day. Hopefully some day, I will have all of the pieces of my puzzle put together to be able to compete with you guys in league racing. With that said, I am the type of person that wants to know the hows and whys, purely out of curiosity and my love for learning. This stuff is fascinating to me and obviously at least a few other people on the forum. Nobody is trying to one up anybody else. We are not bending the the laws of physics for the benefit of some hidden agenda. Again, we are all basically saying the same thing. Grooved Axles do indeed appear to be faster! But maybe not for the reasons you think! Just laying it out for those that might be curious about the whats, hows, and whys.

 

[Mr Chips Racing]

Here we go boys this is what I'm talking about. A good 'ol debate. Should we break out the politics and religion?

I do enjoy the likes of people who "think" they are smart. I also enjoy doing what QT mentioned. Do any of you remember that guy who was the physics teacher that was fast? NOT. How about putting your car on your treadmill.... That was a good one. Or wait make a paste with graphite and "pack" your wheels.

Folks we may not have a Mr. Butterhole but it looks to me we are in the dawn of a new era of individuals who like to preach and once again do not race.

Oh and in my experience.... Grooved axles are faster for me.

 

[Obsessedderbydad]

Gosh... I knew I should have stayed away from the PWD forum a while longer. While you guys argue about friction and gravity or what ever, I'm going racing. Racing these cars is all about overcoming friction and gravity. I don't know or care how much or little friction there is between axles and wheels. That's why we prep everything, that's why we polish and wax and buff everything! All together now! Polish, wax, and buff! Lets race!

/images/boards/smilies/thumb.gif

 

[Mojo Racing]

And it is not that I do not race... it is just that I have not had a car in here yet. I will totally be at the MA and Fire series in here....

And if someone else would have had a car in the race this Saturday, I would have made sure one of mine was here.

I was TOTALLY willing to stand behind my experience with one of my cars.