Gear ratio help

[Opossum]

So all you know I'm putting a 10/12 combo under the yota, coming sooner than everybody though hopefully.

Before I got the axles I was told it was a 44/12 not really a big deal that it wasn't but that's besides the point. The guy I got it from said they had 4.10 in them, now exactly how can I tell what ratio is in them. I pulled the front cover today just to inspect it since when I opened the rear the teeth on the ring gear were chipped. I counted the number of teeth on the ring gear is 40 and it was getting dark and I couldn't get an accurate number on the pinion. also the numbers on the ring gear read 30139848281340878 .

so what ya'll think?

Cliffnotes:

Ring gear teef count = 40
ring gear number = 30139848281340878

 

[vanguard]

I think you need to count the number of teeth on the pinion. I also suspect there are 41 teeth, not 40 and that you'll find 10 pinion teeth.

41/10 = 4.10

But that's all a guess. If you really want to know you have to count them.

 

[Opossum]

thats what I was thinking but I could of swore it was just 40 on the pinion.

 

[blacksheep10]

41/11 is a 3.73
41/10 is a 4.10
40/13 is a 3.08.

I hope like hell I didn't see a 13 40 8 78 on there. that would be 13 pinion and 40 ring. that's a 3.08 made in aug of 1978.


easiest way, spin it. no mistakes then. no need to ever ever ever pull a cover to find gear ratio. on a front you don't even need a jack. I always spin 1 tire. reason being you don't have to worry about spinning each tire exactly 1 turn. you jack up 1 tire and mark the tire. you spin the driveshaft counting turns of the shaft until the tire goes 2 turns (2 turns because the spiders transfer the turn of the static tire to the spinning tire). I normally have a marker in my pocket so I can mark the tire and pinon. all the ratio means is the driveshaft will turn x times before the tire turns 1 time. meaning with a 4.1, the pinion or driveshaft will spin just barely over 4 times before your tires go around once, or 1 tire goes around twice.
a 3.73 will have the shaft turn 3 and 3/4 times for a turn of the carrier. 3.08 is just over 3 turns.
with a front you just lock 1 hub and unlock the other. lay under it, and spin the pinion while watching the shaft turn twice. that way there is no cover pulling.

 

[Opossum]

I hope like hell it's not a 3.08 either but they did come out of a 78 or 79

 

[blacksheep10]

79 most likely being a 10 front 12 rear. 78 was *MOSTLY* 44 fronts and 12 reas were in there until 81. just go out and spin it and see. if not, the one with the cover off, its right on the ring gear. it'll say it in groups. I didn't see a 41 in that group. 41 10 xxx is what a 4.10 will say

 

[Opossum]

here's the numbers with all the spaces and dash

3 01 3984828-[size=10pt]13 40[/size] 8 78


well from what I've gathered over the interweb looks like I've been had o well I'll street it with some street tires. I'm bummed as hell now.