Noob axle question -
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Unread 12-02-2013, 02:47 PM   #1
Registered User
1987 YJ Wrangler 
Join Date: Feb 2013
Location: Staten Island, New York
Posts: 64
Noob axle question

Hey all..

I've had my yj about a year and was looking to put in a new rear. I don't know what gear ratio i currently have though. I have an 88 4.2L I6 engine with the AX-15 tranny and NP231 transfer. currently running 33x12.5 tires and can get into 5th gear while driving most of the time and stay at a steady rpm. any idea how to find out my gearing/locker set up?


[B][I]Staten Island[/I], NYC
[/B] [COLOR="Black"]87YJ[/COLOR] 4.2L 5 spd with some cool stuff done to it.
[COLOR="Navy"]US Navy Jeep Club Hull# 231[/COLOR]
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killakeane is offline   Reply With Quote
Unread 12-02-2013, 03:22 PM   #2
Registered User
1993 YJ Wrangler 
Join Date: Jan 2009
Location: East Bay, CA
Posts: 398
I mean, the stock set up is 3.07 gearing with an open differential yeah?
If you need confirmation then open it up!
seeing as you want a new rear, I'd only open the front,
as the old rear gearing doesn't really matter, as it's going to be replaced.

when you crack it open it'll look like this-

well close....
this is a 35, the rear, with 4.10 gearing.
so on yours spin the ring gear until you can see the last numbers (mine is 37/9)
divide (36 goes into nine four times with 1/9 remaining, which is 4.1 with a repeating decimal, the closest ratio to that is 4.10)
should be 3.07
then look at your differential,
if it looks like this:

it's open.
if not, then describe or take a picture, then we can tell you what it is, if you don't recognize it.
Project #1-
flipit is offline   Reply With Quote
Unread 12-02-2013, 04:25 PM   #3
Joe Dillard
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1991 YJ Wrangler 
Join Date: May 2004
Location: King George, VA
Posts: 12,325
Answer is in the Frequently Asked Questions (FAQ) sticky thread, in the stock specs area.
Joe Dillard is offline   Reply With Quote

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