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  1. #1
    RC poster
    Join Date
    Oct 2019
    Posts
    1

    Pinion size and upgrades

    Hello,

    This is my first post and I am new to RC cars. Iíve had my Rustler VXL 4x4 for a few weeks now. I love it. So much fun to bash. I have a couple questions that Iím sure someone can answer.

    With the included 17t pinion what happens if you run that all the time? In the manual it says only for hard surfaces. What happens if you run that pinion in grass and dirt? Are there upgrades that I can do to run the 17t pinion full time? Only modification I have done is replacing the shock caps with aluminum ones. I have a 2cell and a 3cell battery. I love the speed of the 3cell with the 17t pinion.

  2. #2
    RC Competitor
    Join Date
    Mar 2019
    Location
    VT
    Posts
    77
    Quote Originally Posted by Rsweitzer View Post
    With the included 17t pinion what happens if you run that all the time?
    You'll be stressing the motor and ESC more than was intended by the vehicle's designers. This 'stress' will likely manifest itself as increased temperature of both the ESC and the Motor. I believe that the VXL3S ESC has an 'over temp' sensor, but I'd not suggest that you rely on that as an OK/Not-OK gauge.
    All else being equal, higher temps tend to result in earlier failure of components.

    You'll also be putting more stress on the drive-line components: pinion and spur gears, slipper-clutch, drive-shafts, wheel-hexes, etc. Stress things hard enough/long enough and they fail. Wrenching is part of the hobby, but the harder you run things, the more parts replacing you'll do.

    With regards to gearing, think of it like riding your bicycle. If you ride in a "high" gear, (large pinion) your legs have to work really hard to turn the pedals, but you go pretty far with each cycle of the pedals. If you shift down to a lower gear, the pedaling is easier, but you go less far with each cycle of the pedals. Modern batteries, Electronic Speed Controllers, and Motors mean that you legs aren't burning, but the ESC and Motor are for sure feeling the heat.


    Quote Originally Posted by Rsweitzer View Post
    In the manual it says only for hard surfaces. What happens if you run that pinion in grass and dirt?
    As stated above, the motor and ESC will get hotter than if you were running on low-rolling-resistance surfaces. Pavement is smooth and "easy" to roll over. Grass has more resistance, and that resistance goes up with the length of the grass. If you are running on a Golf Green (super smooth, well kept very short grass) you'll have less resistance than if you were running on a suburban lawn that has not seen a mower in a month.

    The bicycle analogy works here too: When riding a bicycle on pavement, it's easier to pedal than on grass or loose dirt... same for the RC Car.

    Quote Originally Posted by Rsweitzer View Post
    Are there upgrades that I can do to run the 17t pinion full time? Only modification I have done is replacing the shock caps with aluminum ones. I have a 2cell and a 3cell battery. I love the speed of the 3cell with the 17t pinion.
    If you run your car almost exclusively on pavement, then give the 17T a go full-time. See what happens. Get an infrared temperature gun so you can keep track of how hot the motor and ESC are getting. If they are getting "Too Hot" (and I'll let those that run harder chime in with what are the upper limits of temps to run at consistently), you can start putting fans on the ESC and Motor, gear the car down some, or try driving more 'gently' (likely some combo of all three would be required). If that does not work, you can consider up-grading the ESC and Motor with larger, more powerful units, but realize that you are then REALLY gonna be breaking more driveline parts (that are also up-gradable, but how far you wanna go?).

    This hobby is all about having fun, and yes, sometimes breaking a few things along the way. Enjoy yourself, but be prepared to buy some parts and turn some wrenches along the way.

    I'm somewhat new-ish to the hobby myself, so hopefully more experienced folks will correct me if I went astray here. --BillJ

  3. #3
    RC poster
    Join Date
    Oct 2019
    Posts
    1
    Quote Originally Posted by Single_Trac View Post
    You'll be stressing the motor and ESC more than was intended by the vehicle's designers. This 'stress' will likely manifest itself as increased temperature of both the ESC and the Motor. I believe that the VXL3S ESC has an 'over temp' sensor, but I'd not suggest that you rely on that as an OK/Not-OK gauge.
    All else being equal, higher temps tend to result in earlier failure of components.

    You'll also be putting more stress on the drive-line components: pinion and spur gears, slipper-clutch, drive-shafts, wheel-hexes, etc. Stress things hard enough/long enough and they fail. Wrenching is part of the hobby, but the harder you run things, the more parts replacing you'll do.

    With regards to gearing, think of it like riding your bicycle. If you ride in a "high" gear, (large pinion) your legs have to work really hard to turn the pedals, but you go pretty far with each cycle of the pedals. If you shift down to a lower gear, the pedaling is easier, but you go less far with each cycle of the pedals. Modern batteries, Electronic Speed Controllers, and Motors mean that you legs aren't burning, but the ESC and Motor are for sure feeling the heat.




    As stated above, the motor and ESC will get hotter than if you were running on low-rolling-resistance surfaces. Pavement is smooth and "easy" to roll over. Grass has more resistance, and that resistance goes up with the length of the grass. If you are running on a Golf Green (super smooth, well kept very short grass) you'll have less resistance than if you were running on a suburban lawn that has not seen a mower in a month.

    The bicycle analogy works here too: When riding a bicycle on pavement, it's easier to pedal than on grass or loose dirt... same for the RC Car.



    If you run your car almost exclusively on pavement, then give the 17T a go full-time. See what happens. Get an infrared temperature gun so you can keep track of how hot the motor and ESC are getting. If they are getting "Too Hot" (and I'll let those that run harder chime in with what are the upper limits of temps to run at consistently), you can start putting fans on the ESC and Motor, gear the car down some, or try driving more 'gently' (likely some combo of all three would be required). If that does not work, you can consider up-grading the ESC and Motor with larger, more powerful units, but realize that you are then REALLY gonna be breaking more driveline parts (that are also up-gradable, but how far you wanna go?).

    This hobby is all about having fun, and yes, sometimes breaking a few things along the way. Enjoy yourself, but be prepared to buy some parts and turn some wrenches along the way.

    I'm somewhat new-ish to the hobby myself, so hopefully more experienced folks will correct me if I went astray here. --BillJ
    +1

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