gear calculation question

[romulus22]

I'm looking at buying the RC4WD 2spd tranny and i was wondering if some of you know how to calculate the reduction with different size pinions.

its listed on its site as..... 6.7:1 (with 8 tooth pinion gear) or 11.4:1 (with 8 tooth pinion gear)

also states it is 8-20 tooth compatible

[ultimate_monkey]

devide the # of teeth on the spur gear by the number of teeth on the pinion.. example: 87t spur devide by 14t pinion = 6.2 :1 reduction

but in this case you would have to know the #of teeth on the hi and low gears.. so lets say high is 50teeth and low is 87 devide those by the size of pinion you use

[romulus22]

i would think that would be the case if it were a two gear transmission like a rear end. transmissions use multiple gears which is why i don't know how to adjust the calculation from an 8 tooth pinion to a 20 tooth

[ThunderVP]

If you have a known ratio, 6.7:1 with a known pinion, 8T, multiply the 2 together then divide by the pinion you wish to change to. (internal gears don't matter because you have a known ratio)
6.7x8=53.6
change to a 10T
53.6 / 10 = 5.36:1 or 20T = 2.68

11.4x8=91.2 / 10 = 9.12:1 or 20T = 4.56

[sweli]

Half way down this posting, someone talked through the different ratios:
http://www.rc4wdforum.com/showthread.php?t=8065


Also, PM "greasypete"
He posted that RC4WD had sent him the info.

[romulus22]

Originally Posted by ThunderVP

If you have a known ratio, 6.7:1 with a known pinion, 8T, multiply the 2 together then divide by the pinion you wish to change to. (internal gears don't matter because you have a known ratio)
6.7x8=53.6
change to a 10T
53.6 / 10 = 5.36:1 or 20T = 2.68

11.4x8=91.2 / 10 = 9.12:1 or 20T = 4.56

wow thanks alot

[romulus22]

Originally Posted by sweli

Half way down this posting, someone talked through the different ratios:
http://www.rc4wdforum.com/showthread.php?t=8065


Also, PM "greasypete"
He posted that RC4WD had sent him the info.

thanks also

[BBCorvette18]

good info