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BrianG · 05.06.2011, 11:56 AM

I ran a two-speed setup in my Ofna Ultra GTP (basically an on-road buggy) and it was difficult to control when it shifted. The torque difference between the two speeds would literally cause all the tires to start spinning - and at 40mph+ that can be bad.

Like I said, the problem is the difference in torque. When you are at the upper end of first gear, the motor revs are high. When it shifts into second gear, the motor doesn't drop rpms as fast as a nitro engine does under the new load so it just breaks all the tires loose and you spin out.

To minimize this effect, you'd have to make it so the change in ratio is not dramatic, but if you do that, you aren't really gaining much.

Too bad there wasn't a type of durable CVT which has no shift points, just a constantly adjusting ratio in analog fashion.

But really, if you are shooting for really high speeds, the easiest and best thing to do would be to use a single speed and a larger motor to handle initial starts better and handle the power requirements of the tall gearing.

	(#4)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	05.06.2011, 11:56 AM I ran a two-speed setup in my Ofna Ultra GTP (basically an on-road buggy) and it was difficult to control when it shifted. The torque difference between the two speeds would literally cause all the tires to start spinning - and at 40mph+ that can be bad. Like I said, the problem is the difference in torque. When you are at the upper end of first gear, the motor revs are high. When it shifts into second gear, the motor doesn't drop rpms as fast as a nitro engine does under the new load so it just breaks all the tires loose and you spin out. To minimize this effect, you'd have to make it so the change in ratio is not dramatic, but if you do that, you aren't really gaining much. Too bad there wasn't a type of durable CVT which has no shift points, just a constantly adjusting ratio in analog fashion. But really, if you are shooting for really high speeds, the easiest and best thing to do would be to use a single speed and a larger motor to handle initial starts better and handle the power requirements of the tall gearing.