I need help with gearing
 

I need help with gearing I'm running a electrix rc circuit and I want to put a viper rc copperhead system I want to know what gearing to use right now I am running a 7cell 4200mah nimh battery but later I will upgrade to 3s lipo

RE: I need help with gearing
 

I'd gear down 2 or 3 on the spur, and later on the pinion.

RE: I need help with gearing
 

what KV is the motor?
when I ran a 4300kv in a ecx boost I found the stock gearing to be very low. I was able to run 2.2 tires and a larger pinion without overheating the motor.
Id start with stock...check the temps. if its high, then gear down. Most likely, you will be safe running the stock gearing and will be able to gear up if you want to.

RE: I need help with gearing
 

Run the stock gears, buy an infra red temperature gun, check motor temps. If motor is getting over 180*F, drop some teeth from the pinion, if it is not even getting to 120 and you want more speed, add a couple of teeth to the pinion.<div>
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RE: I need help with gearing
 

It is a 3900 kv motor and the stock gearing is 20/87

RE: I need help with gearing
 

Your stock gearing is a good place to start. If it's pretty warm where you are, maybe drop the pinion to 19....but like Foxy said, get an IR thermometer for accurate temperature monitoring for gearing selection/confirmation.  I don't know that going 3S is a good idea.......are you sure your drivetrain can handle it?   If you're going for speed runs, 3S would be ok, but for bashing, it's just too much.  Better to spend the $$ on LiPos with a higher C-rating.  .

RE: I need help with gearing
 

Yes most of the time I will be using a 7cell nimh but for speed runs I will use a 3s lipo:D

RE: I need help with gearing
 

Thanks for the help I was going to gear something like 23/82