Spur and pinion

[JBLAST]

Hello, I have a 12t trailmaster 550 Holmes hobby motor and 1080 HW ESC on an SCX10 ii, question is I want the wheel speed and torque meaning like to get up fast on dirt hills or pretty much like bashing, please I need an expert advice on what size spur and pinion before I purchase one. A friend said to use 92t spur and 20t pinion. We're both getting into this EXPENSIVE hobby but sure dam love it.

[twade984]

Honestly, I wouldn’t recommend that motor. If you’re set on using it, then you want to gear down as much as possible. Probably 9t or 10t pinion on the stock spur.

The trailmaster is a 3 slot motor, and that turn count is I think the same as what comes stock in a Traxxas slash. I have a feeling it’s going to feel under powered, and possibly overheat. I’ve never tried it though, so I could be wrong.

A better choice would be a trailmaster in a 21t, or crawlmaster in 8 or 10t. (Crawlmaster is 5 slot, so 8 or 10t is more equivalent in speed to 21t 3 slot)

Also, fyi, 92/20 gearing is 4.6:1, which is slightly faster than a 56/12 spur and pinion. I believe stock is 56/13 which is 4.3:1. Rather than change the pinion and spur (which may not even fit), you can just go to a 12t pinion for the same result.

[CNCist]

youll give up low speed control if you gear it for bashing. the 5 slot motor could give you a better chance of keeping that low speed control. if i were you i'd go high discharge 3s and if the money is there then a cheap 8-10t 5 slot. Either step down the spur (preferred) or step the pinion up a bit try to not add too much mass to the rotating drivetrain.

Know that there is a trade off no matter the electronics. The motor may "unload" when torque is needed to get your truck through a brutal obstacle. i dont know the actual term but it happened to me on a brushless set up, super fun for bashing and a capable trail walker. heavy crawling is possible it just wont have that low end speed control.
ETA: Twade makes solid points im kind of building on that a little. i dont own a SCX10.

[twade984]

Yeah the obvious choice here would by a quality sensored brushless setup to get more than enough wheel speed, while still maintaining low speed control. Something like a 2850kv slate and mamba x/copperhead/possibly micro x.


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[JBLAST]

so a 92t spur and a 20t pinion seem good???. and yes I already have 2 HH crawl master 8T on Amain cart. thank you for your response.

[twade984]

Originally Posted by twade984

92/20 gearing is 4.6:1


Rather than change the pinion AND spur (which may not even fit), you can just go to a 12t pinion (and reuse the stock 56t spur) for the same result.

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