Originally Posted by
Svendc
66t spur 44 pion gives ratio 3.0, if you dremel de motormount, i think its possible to place up to 50 pion. so 2.64 ratio
only done, if you want do a freaky speedrun
Sounds like 48-pitch gearing. I installed an 88-tooth spur (the equivalent of your 66t spur in 64-pitch) and the 44T pinion needed to get 2.0:1 doesn't QUITE mesh enough. I'm sure some short work with my round needle file would get 'em close enough.
I should be clear I am aiming for spur/pinion ratio range of 1.75 - 2.0:1, NOT FDR. The FDR range I run (VTA) is always in the 3.5-4.0:1 range. I'm not looking for crazy low ratios for speed runs with my poor lil' 25.5 motor.
Maths for spur equivalents: people always seem to wonder how I do stuff like this. You set them up as proportions, cross-multiply, and solve for your unknown value...OR as works in practice, multiply the two known values that are "crossed", then divide that product by the remaining known value to find your unknown.
In this case I took my known combo and compared it to your combo that I didn't know the pitch for sure.
88/64 = 66/X...(64 x 66)/88 = X...X=48, so the 66t spur in 48p matches the 88t spur in 64p. OR you could just look at the numbers and note that 66 is 3/4 of 88, 48 is 3/4 of 64 so it works out.
Where this gets "handy" is now as I'm contemplating moving from the 64p gears I've used since '86 now to the Lee Speed 84p gears. I used the same proportional algorithm to find that I need a 115.5t (116) to replace the 88t spur. Instead of filing the slots to get a little closer mesh I can go up a touch since the Lee Speed spurs hit all the even numbers. A 116-58 combo would probably be "there", I'm pretty sure a 118-59 combo will be spot on.