Hi everyone! My first post on here. I have a 2012, 2 door, JK Sport, automatic transmission with the 3.6 Pentastar and 35's. I'm looking to redo my gears. I'm being told to go with both 4.56 or 4.88. The crazy thing is when my husband called 4 wheel parts he was told by one employee to go with 4.56, then online another employee told him 4.88. It came with 3.73 and with the 35's the mileage stinks and performance leaves a lot to be desired. It is a daily driver and only light trails. Has anyone made the upgrade on a newer JK with the new 3.6

 

Welcome to the group, there's a gear chart I have somewhere give me a minute ill look for it and post a pic

 

Here it is hope this helps you with your decision. Post pics of ur jeep too

 

Thank you and I will post pics in just a bit.

 

DO NOT go by that gear chart.

If you want some power back, maintain OD on the hwy, and still get decent gas mileage the only 2 choices are 4.10s or 4.56s.

4.88 is way to much gear for a DD that only sees light trail use.

I run a 2012 Auto with 4.10s and 35" KM2s and I run 2425 RPMs at 70MPH. 4.56 will run about 2650 at 70 and about 2900 at 75-77MPH.

4.10s cost way more because spicer seems to be the only company making them for a D30/D44 combo. just make sure if you go with 4.56 you don't go with he G2 crap that 4WP tries to sell. Get a good R&P and get someone that knows gears to do the proper pre load, etc.

 

4.10 and 35s are very nice combo Im running this and I do trails 1 or 2 time a month right now and all the rest its DD and have had 0 problems plus i keep the OD on

 

3.73's with the 3.6L isn't a huge difference than 4.10's and the 3.6L, I don't think it's worth it going up that much might as well do 4.56's if ur set on changing. I have buddy's with 3.73's and its barely any different than driving my rubi with 4.10's and 35's.

 

Why not go by the chart it's saying exactly what u said, 4.10's or 4.56's??

 

The chart is pretty accurate after just having a 2012 Sport with auto and 3.73 gears I noticed a little bit of power loss, but I only lost about 1-1.5 mpg. Personally 4:10s or 4:56's would be adequate. I would only consider 4.88's if all your time was offroad, you had a 3.8 instead of a 3.6, or you were considering going to 37's at a later date.

 

Oh and by the way the 2012 is now a 2013 Rubicon with a manual and 4.10s. With the manual might prefer the 4.56's over the 4.10's.