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View Full Version : final drive ratios...


Slyp Dawg
26-07-2011, 03:55 AM
about what's the lowest one can go on the final drive ratio on a touring car and still have it be usable with a regular 540-can brushless motor? I'm custom making the gearbox using the spool and idler pulley from an Axial AX10 gearbox, since the gears are 48p, and the idler gear appears to have the same tooth profile as 48p spur gears. the diff gear is 52t, with the idler gear is 28t, giving a 1.857:1 gearbox ratio. since the idler pulley is the same profile as a spur gear, I am going to use it as such. the smallest 48p pinion in existence is 10t, so the numerically highest final drive ratio that can be had is 5.2:1, whereas the numerically lowest final drive ratio that can be had is 1.106:1, using a 47t pinion. I have a feeling this will put a lot of strain onto the motor, but since this will be 2wd rather than 4wd (lighter and less mass to accelerate) and there are some very very torquey motors made for crawlers (IE the Novak Goat and various outrunners), I'm hoping that I won't be building a medieval torture rack for motors, but I'm honestly not sure. anyone got any input? I may have put this in the wrong forum, and if I did, terribly sorry, I figured the custom nature of the project would make it fit in better here