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Old 08-28-2009, 05:49 AM   #16
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Other way around
Oh ok. I didnt know what was going on
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Old 08-28-2009, 08:02 AM   #17
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64 is what i was told all the "cool" guys run.


lol,

ive always ran 64p for touring 48 for offroad.
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Old 08-28-2009, 08:30 AM   #18
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I'm not so sure about 64p being more efficient than 48p. I agree with Geezatec, there is more surface area in contact between your pinion and spur with 64p compared to 48p, which is why it runs quieter. The primary advantage is the ability to get finer gear ratio selectivity. This is more important when running foams where tire diameters vary so greatly compared to rubber tires. I think 64p has its greatest benefit in 12th scale racing.
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Old 08-28-2009, 09:52 AM   #19
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I'm not so sure about 64p being more efficient than 48p. I agree with Geezatec, there is more surface area in contact between your pinion and spur with 64p compared to 48p, which is why it runs quieter. The primary advantage is the ability to get finer gear ratio selectivity. This is more important when running foams where tire diameters vary so greatly compared to rubber tires. I think 64p has its greatest benefit in 12th scale racing.
It has been said already. Being quiet is a sign of efficiency even if only you look at noise as energy being wasted.

But that is just a perk on the side. The higher contact area and the closer mesh allowed are the reasons behind higher efficiency of the 64 pitch.

Xrays don't allow 64 pitch unless you modify your spurs to allow access to the motor screw. Not sure about all of them but 007 is like that. You also need to modify the spur holder if you can't get spurs with six holes.

And yes, I am in the 64 camp.
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Old 08-28-2009, 09:53 AM   #20
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I'm not so sure about 64p being more efficient than 48p. I agree with Geezatec, there is more surface area in contact between your pinion and spur with 64p compared to 48p, which is why it runs quieter. The primary advantage is the ability to get finer gear ratio selectivity. This is more important when running foams where tire diameters vary so greatly compared to rubber tires. I think 64p has its greatest benefit in 12th scale racing.
64P on 12th scale is great!! Also with 10th scale On-roads. 64p gears are good with on-roads indoor, racers on asphalt depend on preparation of track, being swepped with a broom or blow swepped. Off-roader stay with the 48P, their more durable with pebbles and dirt. They will not be chewed up cuz the fine teeth on 64P gears. You will see that nitro will never use 64P gears especially off-roaders.

Geuss we can tell the racers and the bashers between on use of 48P/64P gears.
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Old 08-28-2009, 10:07 AM   #21
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Being quiet is a sign of efficiency even if only you look at noise as energy being wasted.
I don't disagree with you, but more contact area will mean more drag. Whether or not this can be felt on the track is certainly debatable.

I like 64p where I can get away with it too...love a quiet car on the track.

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Old 08-28-2009, 10:10 AM   #22
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The biggest benefit of running 64p indoors is that if you need to bum a pinion or spur, everyone will have one, not too many people run 48 indoors
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Old 08-28-2009, 10:19 AM   #23
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I agree with this. Everyone runs for the most part 64 pitch in their touring cars at my track but I run 48 for the ease of the gear mesh as you have a little more room for error. I have plenty of gers and spurs so getting the gear ratio I want isn't a problem.

Overall I have always found 48 pitch to be more reliable overall with no loss in speedo and still efficent.
+1

I run multiple classes so things can be a little hectic in the pit. 48 pitch is much easier to work with, pretty bomb proof and is cheaper on the pocket book in the long run. I use the same gears for both off road and asphalt on road racing. 64 pitch is a bit overrated for 1/10 sedan rubber tire racing. Foam tire racing I can understand.
A multi national winning motor builder tested 48 and 64 pitch and told me his dyno showed that both pitches were pretty even efficiency wise but the 64 pitch lost a lot a efficiency if you didn't set the mesh perfectly. That comment has always stuck in my mind.
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Old 08-28-2009, 10:56 AM   #24
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64p has no ratio advantage over 48p. In the real world you can change both your spur and pinion to get the excat ratio you want. I run 48p because it is more reliable. Weather it is better or not is such a minute difference that I wouldn't even bother thinking about it.
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Old 08-28-2009, 11:06 AM   #25
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I think in the old brushed days, 64P was a lot more efficent because there were more teeth in contact so the force was more tangental instead of normal to the gear interface. If you look at a 10-12 T 48P, they only had one or two teeth in contact at once. So a lot of the energy went into pushing the gears apart. Now with 40+ tooth counts, almost all the force is tangental since several teeth are always in contact.

I run the 64P because I run indoors on carpet and that is what everyone runs. Nice and quiet, cost is no different and life of the gears is good. So I see no need to go to 48P. If running outdoors, I would probably go to 48P for the increase in durability.

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Old 08-28-2009, 11:20 AM   #26
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Originally Posted by Old Tech View Post
I don't disagree with you, but more contact area will mean more drag. Whether or not this can be felt on the track is certainly debatable.

I like 64p where I can get away with it too...love a quiet car on the track.

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I pondered the question many times myself. Without proper testing and figures I can not make the argument. But you can visit a lot of websites of engineering departments at various universities around the world which will explain the math behind it and it is compelling if you're patient and know your math. True, one would think there is more surface area, but then again the force is distributed over all this area, and friction depends on surface AND force normal to the surface. I think the equation goes up quicker with force than surface which is why you prefer to distribute your force as much as you can so there is less force per unit of area. More gears in mesh means more area, but it also means less force needed per unit of area to produce the same effect. But all that may be just wanky claptrap in fact since in theory the contact should be not a surface but a line with correctly cut gears (we're talking straight cut gears here, not bevelled or hypoid), so in fact you can reduce the discussion at the number of teeth in contact which gives you more lines of contact for 64 pitch therefore a more direct arrival to the idea that more contact needs less distributed force so less friction (less heat/noise=waste).

Also, using larger diameter spurs (an 80 tooth 48 pitch spur has the same diameter as a 120 tooth spur at 64 pitch) gives your motor better leverage to turn the spur (physicists would say better radius, therefore higher torque), so there you go, another way to increase efficiency (albeit indirectly, I mean not inherent to using 64 pitch but a side effect of it).

And here's a secret. I went to the dark side when I bought my Kawada Sigma2 and discovered their 64 pitch gear which to this day I have to see betterred. My car is literally silent as a ghost. All my cars now run these (except for that dang Xray).

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64p has no ratio advantage over 48p. In the real world you can change both your spur and pinion to get the excat ratio you want. I run 48p because it is more reliable. Weather it is better or not is such a minute difference that I wouldn't even bother thinking about it.
In figures (numbers) it would look that way. 90 tooth spur with 30 tooth pinion is still 1/3 ratio no matter what the pitch. But changing the spur form 90 to say 80 means a smaller diameter difference if you talk 64 pitch then the same difference with 48 pitch. That's what people mean when they say "ratio advantage". Otherwise, there is no difference. But that is enough. It means that with 64 pitch you can have a wider range given that the motor has a (sometimes very) limited adjustment possible in the car before you run out of room and/or gears can't mesh anymore (see that dang Xray). Ergo, you get more gearing options. It's just a shorthand expression for all the yadda yadda above. Not that everybody would (or could) explain it.
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Old 08-28-2009, 11:59 AM   #27
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True, one would think there is more surface area, but then again the force is distributed over all this area, and friction depends on surface AND force normal to the surface.
On most things surface area is not part of the friction force, just normal force and material. This is not always true, but for most materials it is. Rubber is one that it is not once you reach a certain normal force the friction no longer increases.

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Old 08-28-2009, 12:15 PM   #28
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On most things surface area is not part of the friction force, just normal force and material. This is not always true, but for most materials it is. Rubber is one that it is not once you reach a certain normal force the friction no longer increases.

John
That sounds credible if one accepts that some materials will distort beyond a certain force threshold therefore not impart any further force increase. Perhaps that's why spurs need to be tough so they take all of the force instead of wasting some of it in elastic deformation. (Kawada advertise their spurs as "super tough").
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Old 08-28-2009, 12:18 PM   #29
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Xrays don't allow 64 pitch unless you modify your spurs.
WHat? My Xray "allows" 64 pitch just fine, and I haven't modified a single thing. Actually, my Xray CAME with a 64pitch spur gear.
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Old 08-28-2009, 12:28 PM   #30
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WHat? My Xray "allows" 64 pitch just fine, and I haven't modified a single thing. Actually, my Xray CAME with a 64pitch spur gear.
There's a caveat in my post capt'n.
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