RC Gearing Question

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Lion1

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I have an SC10 with a castle creations brushless motor that I usually run on a 2s dynamite Lipo. I was running a 14 tooth pinion and the stock 87 tooth spur gear until the spur stripped from the pinion setscrew coming loose and slipping off the motor shaft. I ordered a new 77 tooth spur gear. I went to install it but the motor cannot slide forward enough to fit the 14 tooth pinion. I have a pinion sitting around that is a 21 tooth that I can put on. I was wondering if that gearing combo of a 21 tooth pinion and a 77 tooth spur would work ok based on the electronic I have. Do you think it will make the motor too hot?
 

cbaker65

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I have an SC10 with a castle creations brushless motor that I usually run on a 2s dynamite Lipo. I was running a 14 tooth pinion and the stock 87 tooth spur gear until the spur stripped from the pinion setscrew coming loose and slipping off the motor shaft. I ordered a new 77 tooth spur gear. I went to install it but the motor cannot slide forward enough to fit the 14 tooth pinion. I have a pinion sitting around that is a 21 tooth that I can put on. I was wondering if that gearing combo of a 21 tooth pinion and a 77 tooth spur would work ok based on the electronic I have. Do you think it will make the motor too hot?

If you do the math on that ,it appears that the change is only a 3 tooth difference in comparison ,you
should be safe!
When I experiment with gear ratio's ,I only do 2 teeth steps ,however you are going larger on the
pinion ,I am not sure if that will make a difference on the heating or making the motor run hot ,
the only way to tell ,is to try it ,but monitor it!.. :thumbs-up:
 

Lion1

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Ok great. I can always turn down the power to the motor on my radio to try and manage the heat a bit.
 

Greywolf74

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If you do the math on that ,it appears that the change is only a 3 tooth difference in comparison ,you
should be safe!
When I experiment with gear ratio's ,I only do 2 teeth steps ,however you are going larger on the
pinion ,I am not sure if that will make a difference on the heating or making the motor run hot ,
the only way to tell ,is to try it ,but monitor it!.. :thumbs-up:
The number of teeth total isnt really whats important, the gear ratio is. His starting gear ratio is 6.2:1 and his new gear ratio is going to be 3.6:1. Thats a huge decrease in gear ratio. By going both smaller on the spur and larger on the pinion, both moves are going to yeild higher top speed and of course more heat. My advice to the OP is you can try it but keep an eye on your ESC and motor temps.

Is it a 2wd SC10 or a 4WD SC10? you may be able to mod the motor mount with a dremel in order to get more room to position your motor.
 

Greywolf74

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I've never owned an SC10 and just looking at pics on google trying to see if you can dremel out the screw mounts to get more movement but I'm not able to tell because the motor has a casing around it.

So basically the SC10 transmission/motor housing is very similar to this one, although this one is technically for a Rustler.
51iEOE0PNoL._AC_SL1000_.jpg

The black plastic part of the transmission that the blue motor mounting plate is attached to is going to limit how much you can move the motor around even if you used a dremel to extend the motor mount screw slot(s).

If you're able to find an after market transmission/motor mount like the one below then you remove a lot of the restrictiveness and the motor will be able to move more. You may not even need to mod the after market piece
HRATE12HX01_A0_DEFEVBS5.jpg

now, again this one is from a Rustler and I'm just using these to demonstrate what I'm talking about because I'm familair with this kit but not yours. They do have a lot of similarities though so hopefully this info can help you figure out a good after market part to buy or a way to mod your existing one.
 

Lion1

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OK, I might try out the new gear ratio and start on low power to see how it goes.
 

tntpoof

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with gear ratio listed that is major . its going to cause heat fast. replace old pinion and run old spur..check heat often turning punch down might cause it to heat faster.
 

Lion1

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The old spur is stripped and if I try to fit the old pinion to the new 77 tooth spur the pinion won’t reach it.
 

Greywolf74

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The old spur is stripped and if I try to fit the old pinion to the new 77 tooth spur the pinion won’t reach it.
I believe he meant order a replacement spur that is the same size as the stripped one and use the original pinion too.
 

Lion1

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Ok, I got the spur gear that doesn’t fit refunded. He said I could keep the gear which is really nice. I think I am going to try it out later today and see how the motor does. I am also probably going to buy a different gear with a different spur count from the one I bough (77) and the stock one (87) and use the stock pinion with it. The 77 wouldn’t fit with the 14 tooth pinion. How many teeth up should I go up to get it to fit? Should I measure the circumference of the gear?
 

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Ok, I got the spur gear that doesn’t fit refunded. He said I could keep the gear which is really nice. I think I am going to try it out later today and see how the motor does. I am also probably going to buy a different gear with a different spur count from the one I bough (77) and the stock one (87) and use the stock pinion with it. The 77 wouldn’t fit with the 14 tooth pinion. How many teeth up should I go up to get it to fit? Should I measure the circumference of the gear?
I couldnt tell you what gears will fit and what wont on that kit. I've never owned that particular one before. I would just buy a few various pinions skipping 2 or 3 teeth with each one so you have a few to try and then you can zero it in from there.
 

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