what pinion gear do i need

[wraithbomber]

I have a 40 turn tekin with fxr esc, stock spur gear. What pinion should I use ? Just for crawling no speed runs my wraith

[Revoasian]

This is a pretty broad question but here is my 2 cents. Your 40 turn motor I assume is brushed motor? If so it's very close to my 18.5 brushless sensored motor which equates to roughly a 35-45 turn lathe or crawler motor. If low speed crawling is what you enjoy most I would shoot somewhere between 5-6:1.1 ratio in a 32 pitch gear setup. I run a 58/10 and the spur gear fits under the stock cover no problem, that gives me a 5:8.1 ratio and its just a dedicated crawler only. I have no over heating issues at crawling speeds at all, however half throttle and above short bursts is another story. Oh, I am also running O/D and U/D axle gear sets too incase you were wondering if that would work, helps with better turn radius and getting over verticle climbs easier. ( Helps keep flipping over backwards to a minimum ).