Help! I'm Gear-Ratio 'tarded!

qbracken · **Posted:** Mon Sep 08, 2008 12:09 pm

So after reading numerous posts trying to figure out what people are talking about when discussing gear ratios, I guess I am even more confused.... Maybe it's because I suck at math?.... My eyes tend to glaze over when discussing fractions/decimals/percentages, lol....... How many different Gear-Ratio combinations have come out in the KJ's over the course of it's production life?

I have an '06 with an Auto Tranny and the tow package; does that mean it has a different gear ratio than one built the same year without the tow package? Does it get better or worse gas mileae because of it?

Thanks!

bugnout · **Posted:** Mon Sep 08, 2008 1:00 pm

Well it depends on what you mean by gear ratios

I'm assuming you mean the differential ring and pinion gears.

You have the 3.73 gears in your differentials. All of the automatics I know of had this gear ratio.
Four cylinder models came with 4.10 gears.
I think the manual transmission 3.7L models came with 3.55 gears

These are the only available gear sets for the front differential. Nobody makes aftermarket gears for the Dana 30a. The rear differential on most KJ's is the Chrysler 8.25, and there are more choices, but since you can't get any other gears for the front they won't do you any good unless you have a 2WD KJ.

jeepkj02 · **Posted:** Mon Sep 08, 2008 1:04 pm

You can get 4.10 gears for both the front and rear diffs. Only needed if you have 32"+ tires on.

jsc7002 · **Posted:** Mon Sep 08, 2008 1:48 pm

jeepkj02 wrote:

You can get 4.10 gears for both the front and rear diffs. Only needed if you have 32"+ tires on.

it should help you even if you have 31" or a butt load of armor on it or if you tow a lot

qbracken · **Posted:** Mon Sep 08, 2008 2:39 pm

So then I guess just because I have the Tow Package doesn't neccessarily mean my Auto-tranny and drive-line gearing is any different than a Libby that came without the Tow Package?

jsc7002 · **Posted:** Mon Sep 08, 2008 3:07 pm

qbracken wrote:

So then I guess just because I have the Tow Package doesn't neccessarily mean my Auto-tranny and drive-line gearing is any different than a Libby that came without the Tow Package?

nope you will have 3.73 and if you crawl under your KJ and look at the rear diff cover there should be a metal label on there that say your gear ratio

pokefan · **Posted:** Mon Sep 08, 2008 3:54 pm

why we're on the "gear-tarded" subject. I'll ask a question too...

If I want to replace my rear w/ 4.10's do you have to do the front to match as well? :oops:

tommudd · **Posted:** Mon Sep 08, 2008 3:59 pm

pokefan wrote:

why we're on the "gear-tarded" subject. I'll ask a question too...

If I want to replace my rear w/ 4.10's do you have to do the front to match as well? :oops:

YES,................ well unless you like loud noises coming out from under the KJ :lol:

and then it not moving, if you do not replace both ends the tires will be turning at different speeds...not good :shock:

pokefan · **Posted:** Mon Sep 08, 2008 5:36 pm

lol, That's what I figured I just wanted to be certain.

Help! I'm Gear-Ratio 'tarded!

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