Type of thread on 2 speed pinions

Thanks guys thats a big help. Looks like I might have to use Mike's gears to get the ratio I'm after. The serpent range goes from 15-17 on first and 18-20 on second (not much of a gearing window!) The only problem with Mike's adapter for my situation is it's a tad short. I need about 25mm of shaft before the inside edge of the second gear pinion. Have a look at the picture in post #25 on this page http://www.rc-monster.com/forum/show...?t=9298&page=2and you will see what I mean. The cardboard cylinder represents where the motor can will be positioned.