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Belt Drives/Diffs on offroad cars..why not?

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Belt Drives/Diffs on offroad cars..why not?

Old 05-05-2020, 05:13 AM
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Default Belt Drives/Diffs on offroad cars..why not?

Hi guys, returning to RC after over 30 years. My first car was a Hirobo Bearcat. The car itself suffered from many quality control problems and fell apart easily while running (though interestingly enough it has become enough of a collectors item that I was able to sell it on ebay as is for almost as much as the kit was brand new!). One thing that was very interesting on this 2wd car was that it had both a belt transmission and belt pinion spur. For all the cars quality flaws it ran silky smooth. I understand belts might not be good for offroad cars on dirt because the dirt my lead to damage of the belts, but now that relatively "clean" offroad surfaces such as astroturf and carpet are used for offroad racing, why is no one using belt transmissions/ belt spur pulleys? It would seem there would be less friction than gears leading to more efficient transfer of motor power.
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Old 05-05-2020, 06:58 AM
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Schumacher still does a belt drive buggy, the only manufacturer I might add. Everyone else has gone to the same shaft driven layout, I think it might be because it is faster/more aggressive to drive. It's also tougher, as today's clean surfaces are actually ultra high grip and stresses out the driveline more. The surface under the carpet is also the actual hard flooring of the venue, a belt drive car crashing nose first would cause the belt to lose tension and skip due to chassis flex. A shaft car would more or less maintain gear mesh.

Belt spurs and pinions used to be a thing in drifting a few years ago, but the problem was that there was a limited choice of ratios/pulley sizes. It is also heavier. (2 gears vs. 2 pulleys and a belt.)

I run an older belt car, it is very smooth and quiet.
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Old 05-06-2020, 07:46 PM
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Most offroad vehicles have shafts because they have center differentials. These help with the handling and tuning, which you can't get from a belt system. And as has been mentioned, you really can't afford to have anything get between the belt and the pully, which is difficult on a offroad track that's not carpet or astroturf.

AE had a 4wd SCT that used a belt, that was super difficult to work on. Losi/TLR had a belt driven 4wd buggy. It was super fragile. Also lots of these have high powered motors which are hard on belts. Heck, they're hard on hardened steel driveshafts. Shafts are just more bullet proof.
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Old 05-07-2020, 11:38 AM
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I think the OP was talking about the "Old School" 2wd buggies. In the late 80's there were a few cars, and some aftermarket mods for the RC10 that used a belt to connect the motor to the topshaft of the 2wd car (instead of pinion/spur). I have not seen these on "production" cars outside of Schumacher since 2000ish. I would guess the stress on the drivetrain causes failures on the belt (while being belt driven is much smoother). Images found by Google, credit where due.

Motor to topshaft connection handled by a belt

topshaft to diff connection handled by a belt

Schumacher version of topshaft to diff handled by belt
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