redman619420

Anybody know how to tell what gear ratio is on a stock JK?

jeeperjkj

There are many ways....

• Pull the diff cover and count teeth on the ring & pinion gears
• Jack up one rear wheel, rotate it, count turns on the driveshaft
• Get a build sheet from your dealer (or Jeep.com if you're lucky)
• Compute it by observing your speed in a given gear at a given MPH

... First one is fool proof, but requires removal of diff cover and subsequent refill of diff fluid. Second one takes a bit of time and the ability to do two things at once (turn the tire and count driveshaft revolutions)... more threads out there with detailed instructions for this option. Third is fine as long as you're 100% sure it hasn't been changed. Fourth should be good enough given the spreads on stock gearing.

Fifth and (I think) final option is to just regear and then you'll know for sure what's in it!

jeeperjkj

BTW, it's fairly simple to deduce what gearing you have by the package and options...

So, whaddya got?

X? Rubicon? Auto? 6speed? Tow Package?

tento0929

does changing the gearing help for what????

JKGuy

Lower gears let you get rolling easier, especially with big tires. Lower gears may get better mileage but are sluggish.

jeeperjkj

If you've got a factory tow package, then you'll have 3.73's. If not, then you might have 3.73's, but maybe 3.21's.

Torrin

Then that's your gearing. 2008's did not come with 3.21's.

ringtwins

This is true?

redroc_jk

I have an 08 with a 3.21 gear ratio.

redman619420

Ill look into getting a build sheet....I have an 07 X with the Dana 44 rear with e-locker......just curious to know whats in my jeep...bought new but discarded window stickers....