Hey welcome so seen you post man im in the same boat as you.lol went electric route brushless...running a old bolink pan car 48 pitch 64 tooth spur and. 24 pinion... Motor is a no name brand non sensored motor b3650 4300kv 4 pole 60amp and let me tell ya with setting maxxed out cant hook up at all at any speed.lol toned down setting on my transmitter.actually drivable now...
so anyway what is the pitch on the gear for the nitro jj speed cars? 32 48. Guessing 32 pitch but i could be wrong... I would say start some were around a 20 tooth and go from there maybe higher if you can find a bell gear bigger then a 20... Just note could run into the same problem i had with it not hooking up.
also note i was running mine on ashpault infront ofthe house no prep..so that has alot to do with traction. Keep me posted.