Gear ratio

[ramthis9501]

Stock my truck came with 3.55's. But the cover on the differential has been taken off before. I can tell because it has the red seal coming out the sides. Im wondering if someone put 3.92's in it before me. Is there anyway i can figure it out?

[txbass06]

Jack up the rear end and count how many times the wheel spins when you turn the driveshaft once.
At least, I think that's how you do it lol


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[ramthis9501]

How many times should the wheels spin if their 3.92's?

[garner]

http://www.jedi.com/obiwan/jeep/misc/gearratio.html

[txbass06]

3.92 times
And I had it backwards. Spin the tire once and count how many times the yoke spins lol


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[ramthis9501]

Thanks Garner! I'll have to try that sometime

[004x41500]

or just pop the cover off, and check the numbers that are stamped into the ring gear, then divide the larger number by the smaller one to get your ratio...

*just an example* your numbers are 41 and 10 41/10= 4.11 which means you have a 4.11 ratio

those numbers are the amount of teeth on each gear, the larger number is the # of teeth on the ring gear, and the smaller # is the # of teeth on the pinion gear.

[Redtruck-VA]

jack both wheels off the ground, turn the wheel one full turn and count the shaft turns. 3-1/2 turns =3:55
<4 turns =3:92
4> turns =4:10
4-1/2 turns =4:56

If both wheels turn in the same direction, you some kind of traction control
If the opposite wheel turns the opposite direction, it's an open rear end.
Good luck.

[004x41500]

jack both wheels off the ground, turn the wheel one full turn and count the shaft turns. 3-1/2 turns =3:55
<4 turns =3:92
4> turns =4:10
4-1/2 turns =4:56

If both wheels turn in the same direction, you some kind of traction control
If the opposite wheel turns the opposite direction, it's an open rear end.
Good luck.


hes trying to see if hes got the 3.55 or the 3.92, which would be a hard difference to tell in turning the tires


but that is a very good method

[MikeHTally]

hes trying to see if hes got the 3.55 or the 3.92, which would be a hard difference to tell in turning the tires


but that is a very good methodWhy? There's enough difference in 3 1/2 and 4.

[ramthis9501]

I'm gonna go do it in a little bit, thanks guys

[Redtruck-VA]

Why? There's enough difference in 3 1/2 and 4.

Exactly, my old tired eyes can tell the difference, I know you keen eyed youngster's can certainly get it right.. It's easy..

[ramthis9501]

I just tried it and it WOULD NOT turn. The wheels spun but the drive shaft just sat there. Do I need to disconnect it from the rear end?

[SmokedRam]

You put it in neutral?

[Redtruck-VA]

I just tried it and it WOULD NOT turn. The wheels spun but the drive shaft just sat there. Do I need to disconnect it from the rear end?

Oh Man you broke it!

Not really, have someone hold the other tire or put a block under it so it won't turn.

[Redtruck-VA]

double post, my bad....

[ramthis9501]

Ohhh got it thanks Greg, I'll go try it in a minute

[AWE Daniel]

Colton I highly doubt anyone has changed out the gears, most likely they were just changing the oil like they were supposed to, every 15K miles.

[ramthis9501]

Maybe... but I still just wanna do it cause I'm curious to see. I couldn't get around to it tonight so I'll do it Friday more then likely

[AWE Daniel]

Colton if you request your build sheet like I did then it will tell you what was on it from the factory. I thought I had 3.55 but turns out I have 3.92

[SmokedRam]

Or...look at the decal under the hood...mine has my gear ratio on it...3.55

[004x41500]

were missing the point here guys... hes curious to see if anyone has changed the gears out already.

[ramthis9501]

Yeah I already know it's 3.55 from the factory but I want to see if someone changed over to 3.92. And thinking about it, that wouldn't make much sense to pull off the cover to drain fluid cause it has a drain plug on it. So we'll just have to see

[05singlecabHEMI]

i think the plug is just to add the fluid in. gotta actually take the cover off to drain it. and one thing with takeing it off anda checking it is that your can change out the fluid in there. theres a thought

[SmokedRam]

Yeah, you have to pull the cover to drain, unless someone put an aftermarket cover with a drain on it...

[SLT8]

What's the final drive ratio for your gen?

[AParrette]

i was gonna do 4.10's 4.96 would be way too much

[SLT8]

4.96's are available for your rear?

[AParrette]

it was a high 4 but i don't remember what it was so i guessed

[SLT8]

Cool. I run 4.88's w/ 28" tires but i rarely go over 70.

[ramthis9501]

i think the plug is just to add the fluid in. gotta actually take the cover off to drain it. and one thing with takeing it off anda checking it is that your can change out the fluid in there. theres a thought

Yeah that is a pretty good idea, might do that

[SmokedRam]

that is a good idea...the most commonly overlooked maintenance item is differential fluid...IF you dont know when it was changed last, just change it...

[ramthis9501]

So what kind of fluid does it take?

[AWE Daniel]

I think 75-140 gear oil, but you should check

[ramthis9501]

Alright I'll check, thanks

[SmokedRam]

rear fluid is GL-5 80W90....4.5 pints with 4 oz of friction modifier

only if you are gonna do heavy towing should you use 75W140

[Onk]

There is just too much talk about peoples rears in here....

[Ms.MagnumSLT]

:lol:There is just too much talk about peoples rears in here....

[Redtruck-VA]

So what kind of fluid does it take?

At least no one said scented......