# 39p spur gears??

• 11-22-2012, 01:06 PM
Ed_72455
39p spur gears??
OK, I am in the middle of a bandit project but have a dilemma...

I talked to one of the guys at traxxas and he sent me an e-revo spur and pinion but the 62t 39p is too large. I looked online and found a 55t and am wondering what the size difference is as far as outside diameter so I can guesstimate something for the pinion. it will definitely take several tries and at \$9 a pop, you can guess it wont take too many to figure it out or just give up!!
• 11-22-2012, 11:31 PM
87 GN
I don't know boo about the Bandit, but a Revo spur will fit??
If it does all I have handy is.....OD

68 is 2.205
&
54 is 1.760
• 11-23-2012, 10:26 AM
Ed_72455
that tells me that less tooth count actually makes a pretty big difference in the 32p gears, where the 48p gears being way smaller in height it takes a large increase or decrease in tooth count to really make a difference in diameter.

the examples you gave me are almost half an inch in difference in diameter for only 14 teeth.

basing that information gives me this formula...

2.205-1.760= 0.445
=============
68 - 54 = 14

and using that, if I want to cut that in half, it gives me a drop of 0.2225 inches.... or 7 teeth on a spur gear.

now I have a formula for guesstimating a spur gear and or a pinion gear..

I think !!!!! :confused:
• 11-23-2012, 10:01 PM
87 GN
Well hope you can make that work, or at least get you close to what you are trying to accomplish.........gl2u