Axial scx10 esc & motor upgrade compatability

[belvidere22]

Hello, this is my first post so please be nice !
I have an Axial Rubicon SCX10 which I love ! I've done some modifications and I'm hooked on RC scale crawling...!! However I have a question to hopefully upgrade my motor and esc to provide more torque and a little more speed/power when required...
I've acquired a Hobbywing 120a short course pro sensored brushless esc and a hpi flux pro 21.5 turn sensored brushless motor. These were inappropriately installed in a Losi Comp Crawler I purchased off ebay a while back and on advice of my hobby shop I have removed the motor and esc from the Losi and was going to sell them seprately but wondered if I could fit them in my SCX10 rubicon to achieve the extra torque/power/speed etc ?
If so what do I need to do re gearing ?? I dont understand gear ratio's, pinion gears etc as this is a little too technical for me at the moment however I am keen to learn !! From the ESC instructions the gear ratio I need to consider for a 21.5 t motor is 6.5:1 ? what does this mean ? !
Please advise ! Thanks. Paul

[Charlie-III]

Gear ratio is, spur gear tooth count (T) divided by pinion gear tooth count (T).
Say you have a 80T spur & a 20T pinion, 80/20 = 4, thus a 4:1 gear ratio.

Most crawlers have a ~5:1 to 6:1 motor gearing (pinion to spur) that is adjusted a bit based on motor speed/turns/KV.

Note, on most crawlers, specs on an ESC should include:
1-Instant reverse
2-Drag brake

Tekin FX-R's, pretty much any Castle Creations ESC, Holmes Hobbies ESC's all have these 2 features. Check your ESC specs.

[Olle P]

I'd say the ESC's instructions don't apply to crawlers, but to race trucks!

Compared to the stock 27T brushed motor your new motor has more torque but less motor speed and possibly less power at the same voltage.
You should be able to run it with a slightly larger pinion, and for more speed you need to use a higher voltage battery.

I'm curious as to why this motor was supposedly wrong in an LCC. Should be pretty much the right choice, in my opinion...

[belvidere22]

Hi.. my local hobby shop said the esc wasnt for crawlers... so Ive taken it out... it was set up with a turnigy 3s 11.1v lipo. It seemed to work ok but wasnt smooth at all, very jerky and didnt sound great.... anyway... so ive taken the motor and esc off and want to fit it to my axial scx10 if possible.. if not ill sell them off on ebay....

im not using the losi anymore... just the axial which is obviously a scale truck so want the best of both worlds...crawling and scale racing/bashing

my scx10 runs standard at the momemt with a 2s 7.4v 5000 mah lipo. what size pinion would i need to use and would the battery be sufficient ? at the moment I get run times up to an hour !

I guess i just wanted more torque and more speed when required... can I achieve this or bin the idea ?

[Olle P]

Originally Posted by belvidere22

Hi.. my local hobby shop said the esc wasnt for crawlers...

Very few ESCs are purpose built for crawlers, but we use them anyway!

Originally Posted by belvidere22

my scx10 runs standard at the momemt ... what size pinion would i need to use and would the battery be sufficient?

Using the stock pinion will definitely give you more torque and probably more runtime with the same battery, but you'll probably lose some top speed. Do try this!
(A 5Ah battery in SCX10 normally gives a full day of trail run, so I suppose you drive it pretty hard!)

Then you can test using a larger pinion for more speed, while still getting plenty of torque and a lukewarm motor.

For even more speed add voltage, but keep an eye on the motor temp and be prepared to gear down again. (I ran my rig on 2S but wasn't happy with the top speed. So I did a quick test with two batteries in series and I've stuck to 4S since. I don't do bashing though, but just want more wheel speed available on call while crawling.)

[redsawacs]

they told you it wasnt a crawler ESC because it doesnt have the design characteristics of a crawler ESC, specifically, a drag brake. when you let off the throttle and the truck applies brakes automatically - the hobbywing will simply go into an "Idle" and keep rolling.

You can put any electronic combo in that will physically fit inside the machine. but you will have to alter the gears, power input, etc.

So, basically.....if you put it in and its way to fast, get a smaller pinion gear(motor gear) and a larger spur gear(transmission gear). that will increase your torque and reduce speed. 2s lipo vs 3s lipo will also reduce your speed and will still have plenty of torque. I run a 11/96 on my crawler and a 19/87 on my wraith cars....all brushed motors though.

[belvidere22]

Olle P & Redsawacs thank you for help and advice

I'm going to try out the Hpi motor and the hobbywing ESC in my motor when I get 10mins and see what happens ! ... As you suggest I'll try it with my stock 2s 5000mah battery first with my stock pinion gear

ill let you know what happens !

Paul