What motor KV and spur gear size for AX2 equipped SCX10

[e32lover]

Gday,

I have an SCX10 (well basically just the chassis is SCX10). I will be running it on 3s lipo, all the driveline is upgraded to steel. I also have the RC4WD AX2 2speed transmission installed. I am struggling to decide what motor KV and spur gear size to run for the perfect combination. At the moment it just has the stock 60t 32p spur that came with the AX2. I do a bit of crawling, but mainly just burning around on dirt trails. I will go for a 120amp sensorless brushless hobbywing setup (since I have had that before, but the blue one) and it is pretty tough and never overheated.

So if you guys could recommend a spur gear size and motor KV that would be best suited to my setup, that would be great. Thanks heaps, and here is a pic of my rig thus far.

[TrailDawg362]

I run the Tekin Roc412 1800kV and close to stock gear ratio. 1st gear is about perfect and 2nd is pretty fast. I would stay a couple teeth below stock.

[e32lover]

Thanks. The motor I want is only available in 2000 or 3400kv. I am afraid 2000 will be to slow. I previously had a 3000 (all on 3s) and that was just about perfect, however i didnt have the 2 speed tranny at the time.

Do you think in 2nd gear with a 2000kv motor it will go as fast (top speed wise) as a 3000kv single speed?

My main concern with the 3400kv is not that it will lack torque, but that it will overheat considering it is quite high KV for a crawler, plus my truck is on the heavy side of things I believe.

Cheers.

[talmond]

Senseless brushless in a crawler in general tends to not crawl the greatest. The 2000kv on 3s would be ok. The 3400 on 2s might still be to much speed. Figure that's about a traxxas villineon system and a slash 4x4 is fast. Either way your going to get coggjng issues with sensorless.


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[TrailDawg362]

If it's a 4 pole motor it will have enough torque to spin higher gearing. The Roc 412 is a 4 pole 12 slot sensored motor and runs cool and smooth on 3S. I'd compare your motor's specs to a similar Holmes Hobbies or Tekin to get a better idea of how it will perform.

[e32lover]

Thanks for the advice, so you reckon a good quality 3400kv 4 pole brushless on 3s will be able to power my rig without overheating or any other issues?

[MeanTT]

Drag brake settings are a huge cause of heat issues. I run a leopard 2900 kv 4 pole sensored motor that is sized 3658 (Short course truck size). I run the 48 pitch gears, so it's a little different. The point is that my motor combo works fine and I only use 3S. I really like Leopard motors and strongly suggest them. The are powerdul, run cooler than most, and are economical. I say go sensored, try very hard to use a 4 pole motor, and stay between the 2000 kv and 3100 kv motor. Just do the math and see what the ratios look like. I would multiply all of your gear ratios times the KV of the motor. If your numbers are close, you will have the same speed. If they are higher you will have more speed, etc.

If you divide the number you have with your current set up by the new proposed motor and gearing combo, you can see how much faster or slower the new set up will be on a percentage basis. That's how I figured gearing for my Yeti to get 15 percent more speed than stock while running a 2700kv 4065 motor. Math is your friend. You would really have to try to get a good SCT motor to overheat in a crawler. Crawlers just don't stress the motors in the same way as racing trucks.