I just finished throwing a 4x4 Slash together from spare parts, and used a spare XL-5 with a T12 550 brushed motor system I had lying around. The motor and ESC work great until I attempt to seat the pinion to the spur gear. Then it REFUSES to drive the driveshaft or axles at all.

Is it possible that the XL-5 system is just not strong enough for a 4x4? I have no problem buying a brushless if need, I just want to make sure this is my problem.

Thanks in advance.

Silence from the R/C-Tech guys? That's rare.

I guess I may be the only dummy who has tried this, haha!

Its too weak. Really any brushed system in a 4x4 will be to weak.

How does the truck roll without the pinion? A 12t should at least move it. You need to gear it very low like a 12 tooth or something. Also check the brushes to see if they slide in and out smoothly.

It wasn't rolling. I had the motor out in order to juice and test it. I had a feeling it was to weak when I noticed they use that motor in the 1/16th scale... and here I am trying to push a 1/10 scale!

did you recently disassemble any part of the truck? you could have flipped a diff.

Checked the diffs, those checked out. I have my eyes on the Castle Creations SV3 Sidewinder SCT System 3800kV. Running on 2s LiPo, this should be a solid choice correct?

It's an OK choice.

Really? Why is it just OK? Do you say that because a higher kV is better? Is the 4600kV be preferred?

The motor is good. The ESC is just enough. WP-SC8 is what I put in all my cars aside from 1/8th Truggies.

With the fan on it is just fine. Little warm but not much more than any other esc.

Did some more thinking and tried to do more research. Apparently Castle Creations themselves think that the Slash 4x4 is a bit heavy for the SV3 SCT combos. I do also have MT wheels that I was hoping to bash with.

What if I went with a 1/8th scale?

Castle Creations 1/8 MambaMonster 2 + 2650kV. Or even the Castle Creations Sidewinder 8th + 2200kV. It is waterproof which I like for bashing where ever I want. It is built for larger vehicles so it should handle a heavier truck with larger wheels correct?

That is a bit to much. Go with a mmp/rx8
/hobbywing sc8 esc and 1/10motor of your choice and be done.

You don't need a 1/8th motor. Just a beefier ESC than the SV3. There is a plethora of motors from Turnigy, GForce, Leopard, Tenshock, Hobbywing, Castle in 3660 size with 4 poles. They will all work fine. Out of the ones you listed, I would consider the new Sidewinder 1/8th scale. But it would more cost effective to pickup a combo from China, if you're not in a hurry, from RCEcho, RCMart, HobbyKing, etc. for <$120 shipped.
Here, I'll do some work for you.
ESC: http://www.hobbyking.com/hobbyking/s...dProduct=22632
Motor: http://www.hobbyking.com/hobbyking/s..._Inrunner.html

Or another:
http://www.rcecho.com/HOBBYWING-EZRU...mbo-ME176.html

Or this, if you wanna go cheap:
http://www.hobbyking.com/hobbyking/s...arehouse_.html

Cool. Thanks a ton for the info guys. I really appreciate it.