build a gmaxx and i need help

[suicideneil]

Start with maybe, 18/68, see how it feels and what the temps are like, then bump it upto 22/68 and check temps again. What I did was buy all the available spurs that will fit my tranny, and then picked up a 20 & 24tooth pinion, giving me a wide range of options to tweak the gearing based on the temps and my driving abilities at that speed

3 pinions is usually plenty and they will last a very long time if you get hardend steel versions and use plastic spurs, say 18, 20 & 24tooth, then all the spurs for the 3905 tranny (62,65,68tooth). From what I understand, a smaller pinion than 18t wont mesh with the 68t spur, so that will be the lowest gear ratio you can run, probably good for about 35mph or so.