pinion vs spur teeth

is three teeth difference on the pinion the same as it is on the spur? like is going from a 20t pinion to a 17t pinion the exact same change as going from a 49t spur to a 52t?

[What's_nitro?]

The short answer is no. The pinion is smaller to start with, so the % change is greater. Changing the pinion's size by the same number of teeth as the spur would have a larger effect on the drive ratio.

Example: 20/40 = 2:1, 17/40 = 2.3:1, 20/43 = 2.1:1.

I have heard a ballpark figure is 3 spur teeth is equal to 1 pinion tooth, so if you have data/proof I am wrong please don't slam it in my face.....LOL..I am only being the messenger and dont know for sure

Originally Posted by azjc

I have heard a ballpark figure is 3 spur teeth is equal to 1 pinion tooth, so if you have data/proof I am wrong please don't slam it in my face.....LOL..I am only being the messenger and dont know for sure

Well it has to do with the relation of the spur's size to the pinions size... I think.
It's late and now I just confused myself.

[Sammus]

pinions and spurs give whats called a gear ratio. if you want to compare different gearing, compare the ratio, same number of teeth on spur is definitely not the same as the same number on the pinion.

ok guys, thanks, ive been having heat issues with my 9xl on 4s on a savage and am using 20/49...the only other choice i have right now is going to a 52t spur which prob wont do too much lol...would you recommend 16 or 18 for my next pinion

try din a combo of both the pinion and spur......mayebe going to a 18/52 to start also wheel size plays a part if they are oversize try going to a stock size.....IIRC a stock nitro Savage runs a 14 tooth pinion

[lincpimp]

Originally Posted by azjc

I have heard a ballpark figure is 3 spur teeth is equal to 1 pinion tooth, so if you have data/proof I am wrong please don't slam it in my face.....LOL..I am only being the messenger and dont know for sure

If your pinion is 1/3 of the size of the spur then your ballpark figure is correct. Gear ratios are simple once you understand the overall need for gear reduction. Just divide the spurn tooth count by the pinion tooth cound to get the ratio. The larger the number the greater reduction you have.

49/20=2.45
52/20=2.6

It does not seem like alot, but will make a difference whe coupled with the tranny ratio and the diff ratio.

I run my savage with 14/47 gearing, which has a ratio of 3.35:1. That gives me 40+mph top speeds with the stock 2 speed tranny and 5.75 inch tall tires.

Originally Posted by dpb318

ok guys, thanks, ive been having heat issues with my 9xl on 4s on a savage and am using 20/49...the only other choice i have right now is going to a 52t spur which prob wont do too much lol...would you recommend 16 or 18 for my next pinion

Try the 52t spur, it will lower the ratio a bit and will help with temps. Plus you can do it right now!!!

my tires are losi zombie maxx so they are actually pretty small (slightly smaller than stock i think)

[lincpimp]

I would try the 52t spur, and then go to an 18t pinion if that does not help the heat...

ok thanks

[saydee1800]

what gearing did you find to work?