[RC-Monster Mike]

"Mike,

I guess what I am trying to say is that the people that are having these problems more than likely don't make any other changes than the pinion. They don't change braking force all they do is slap in the new pinion and go for it.

I see it as downshifting, your rolling down the street at 40mph and shift to 3rd then you slow to about 30 and drop it in second the engine reves much higher than it does when your at 30 then you were at 40, basically you are changing the gear ratio.

I never missed that they are traveling at different speeds but when I ran some numbers I didn't some up with enough of a difference.

Could you show your math? I would be interested to see what you came up with. I (according to the speed calculator Brian has made) I only say an 8.62mph difference between the 2 pinions. I would really like to see what you have for total energy that is being dissipated to come from top speed to a complete stop from the 2 different gear ratios with the weight involved.

I also see times where the RPM of the motor is not the same given only the gear ratio change I see a lot of times if the motor is slightly overgeared that it doesn't reach it's calculated rpm."

People are having problems - but i don't think it is fair to say or assume that gearing down(smaller pinion) is the cause of the problems. In fact, the opposite is far more likely to be true. The problem may have shown itself coincidentally when they geared down, or perhaps they were never geared up to begin with. I don't think there is any information or data out there that can make the case for higher failure rates with lower gearing(again, the opposite is likely to be true). Can you show me any significant data that suggests this to be true?

As far as "seeing it as downshifting" - there is NO GEAR CHANGE happening in use, so no downshifting. We don't have a 3rd and 2nd and 1st gear to "shift down to". These are single speed vehicles. Whatever ratio we start the run with, we finish the run with. If it happens to be a smaller pinion, then the resulting vehicle speed will be lower, as will the braking load required to slow the vehicle. I don't see how this can be disputed.

What math do you need to see? Do you really need specific numbers to understand that it takes more energy to slow the same mass from a higher velocity? really? And there is a 12.4 mph difference between a 20t and 25t pinion on the Savage Flux when switching from a 20t to a 25t pinion(with a 5.5 inch tire and 44t spur). With 11+ pounds of mass, this results in a significant amount of extra energy along with less mechanical advantage with the higher gearing. Even the 8.62mph difference at 11+ pounds is significant (run the truck into your shim at 8.62 mph to see the energy it carries).

Regarding the reduced rpm with a taller gearing - perhaps. Unless the gear ratio was extreme and/or the batteries were poor, this is not very significant in my experience(when trying to set a speed record, yes - in daily use - not so much). This speaks to less than ideal batteries, though - which is the primary cause of most problems related to this topic(has been discussed numerous times). Gearing too low is not likely to cause a blown ESC. :)