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Old 05-28-2022, 09:17 AM
  #31  
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Hmm, I just noticed that the diffs don't use the usual large 10x15x4mm outdrive bearings.

Last edited by DavidNERODease; 05-29-2022 at 02:47 PM.
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Old 05-28-2022, 09:51 AM
  #32  
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Awesomatix had an incredible, well developed, well engineered, expensive shaft drive, with years of development behind it.

Despite all that, the A800 was immediately faster in all but the most pedestrian of classes.

So I doubt this revert to shaft drive is going to bring more performance on track.

But it might well sell a load of kits to those wanting something different, which is the main aim of their business, so fair play to them for doing something a little different.

If the price is decent then it could be a great option for the club racer, with a sealed drivetrain and no belts to strip or fall off.
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Old 05-28-2022, 11:28 AM
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Originally Posted by daleburr
Awesomatix had an incredible, well developed, well engineered, expensive shaft drive, with years of development behind it.

*snip*

So I doubt this revert to shaft drive is going to bring more performance on track.
No, not suggesting that. I think the move to belts was "something other than drivetrain efficiency".

If we finally get some class with like.. 40w motors and slippy tires. shafts might make a comeback.

Becuase it's "vaguely related", for the fastest motorcycles working on the raggedy edges of traction, you'll find that they almost universally run V configuration engines, or.. singles. There "is" magic there. The story i'm more attached to, is that the gaps in torque impulse allow the tries to regain grip, or at least allow the carcass to relax. Netting more traction in the end. I... will venture that belts aren't that far removed, by providing some lash in the driveline, they compensate or allow for ~more play~ between the motor and the tire. And they're better at decoupling the transmission from chassis rigidity.
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Old 05-28-2022, 12:58 PM
  #34  
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Guys, be careful calling the 21.5t to 17.5t class slow, because they are fast compared to any stock or 19t class that pros ran in the brushed days. Hell I practiced at 360v2 with a 7t brushed motor of old and there was not much difference down the straight against the 17.5t spec class there or usgt...The Rc market revolves around the 'slow' classes, not the mod class...Shaftdrive advantage there....
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Old 05-28-2022, 02:10 PM
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In the old days, the limit was batteries. So every watt you could save would come out during a race. Efficiency was.. key.

That said, I'm not even sure we have a ~slow~ class. :-) But that's a different discussion.
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Old 05-28-2022, 04:29 PM
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Originally Posted by bertrandsv87
Guys, be careful calling the 21.5t to 17.5t class slow, because they are fast compared to any stock or 19t class that pros ran in the brushed days. Hell I practiced at 360v2 with a 7t brushed motor of old and there was not much difference down the straight against the 17.5t spec class there or usgt...The Rc market revolves around the 'slow' classes, not the mod class...Shaftdrive advantage there....
Pros running 19T? Here pros were mostly running 12T or 11T. USA were already strange in these days lol
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Old 05-29-2022, 01:33 PM
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Old 05-29-2022, 02:04 PM
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2.353 internal? Sounds familiar... yep, same as my 2003 Yokomo SD
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Old 05-29-2022, 09:17 PM
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Originally Posted by DavidNERODease
That's why it was Bert approved....lol....
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Old 05-29-2022, 09:38 PM
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What's wrong with this internal gear ratio?
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Old 05-29-2022, 09:50 PM
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Originally Posted by 4k4m3
What's wrong with this internal gear ratio?
Most cars today have 1.9 to 2.08 internal gear ratio, and that is preferable to 2.353 to 2.5(tc4) due to powerloss since you will have to turn the majority of your drivetrain's heavy parts faster to achieve the same wheel speed: more rotational inertia...You will then need much lighter parts to decrease the excess rotational inertia, which can be very costly....I am not even going to mention high speed shaft harmonics at high rpms that can be reduced with a lower internal ratio....In theory, you want the same internal ratio(or less) as your competitors...
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Old 05-29-2022, 10:28 PM
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Originally Posted by bertrandsv87
Most cars today have 1.9 to 2.08 internal gear ratio, and that is preferable to 2.353 to 2.5(tc4) due to powerloss since you will have to turn the majority of your drivetrain's heavy parts faster to achieve the same wheel speed: more rotational inertia...You will then need much lighter parts to decrease the excess rotational inertia, which can be very costly....I am not even going to mention high speed shaft harmonics at high rpms that can be reduced with a lower internal ratio....In theory, you want the same internal ratio(or less) as your competitors...
The majority? The diffs are the heaviest part, they don't spin any faster. Nor do the driveshafts. The only parts that spins faster is the main drive shaft and crown pinion, and the spur. The diameter of the driveshaft is very small, so the rotational inertia is extremely low.
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Old 05-29-2022, 10:29 PM
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Originally Posted by Nerobro
In the old days, the limit was batteries. So every watt you could save would come out during a race. Efficiency was.. key.

That said, I'm not even sure we have a ~slow~ class. :-) But that's a different discussion.
Efficiency affects speed and acceleration, not just battery life.
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Old 05-30-2022, 01:08 AM
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Originally Posted by bertrandsv87
Most cars today have 1.9 to 2.08 internal gear ratio, and that is preferable to 2.353 to 2.5(tc4)...
Which "most cars" in the touring class? Are you comparing to belts?
Does it really matter in stock racing at 17.5 or 21.5T? I'm trying to understand better.
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Old 05-30-2022, 05:22 AM
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Actually I wouldn't worry too much. Although it can be more difficult to achieve certain final drive ratios with internal ratios like this, but it's nothing I would condemn outright. Just something to keep in mind. For VTA for example, you'll probably need quite a small spur (at least I did when I tried to rebuild my old SD for that class.)

I just found it funny that it was presented as a feature, when the same ratio had been used for shaft drive cars 20 years ago (as I am sure the Yokomo I mentioned wasn't the first).
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