I've got a 2010 sport with 35" duratracs. Which gears should I be running. It's a daily driven, automatic. I do some moderate off roading. Thanks for any advise

 

I'm running 4:10 's in mine and it drives well. Granted I also have a manual. Looking to go to 4:88's for better off road performance.

 

4.10-4.88 for a dd from my understanding.

 

I've got 5.13's and its great with the auto trans. RPM's are good and the power/acceleration is good. Off road is improved as well.

 

Try a search https://www.jk-forum.com/forums/modi...17/#post211276

 

I have a 2011 auto 4 door on 35s and just referred to 4.88. I wish I would have maned up and went with 5.13 but 4.88 are a huge improvement over 4.10s I had.

 

5.13s are the lowest you can go with a Dana 30 front axle. 4.88s would be a waste of money.

This is for an 07-11 automatic.

 

I am running 5.13s and they are great. I've read that those with D30's shouldn't go lower than 4.88s but i have no personal experience with that. I feel 5.13s are perfect for a DD with the 3.8 auto.

 

5.13's.
Next question?

 

I have a 2010 Unlimited Sahara with 3.73, tow package and automatic with 315/70R17 Duratracs. After a year of research, I've decided to go with 4.88. That's just me. I won't be rock climbing, only muddy and sandy trails here in central Florida but I will do some interstate driving to get to my favorite trail/camping spots.

One caution to anyone getting re-geared: If you aren't going to do it yourself (I may), find someone experienced YOU TRUST to take their time to get it right. Gear positioning is done with shims, several assemblies and disassembles (using old bearings and crush sleeve) are necessary to get it right.

Also, you should have someone close by (same town if possible) do the work. After a gear change, DO NOT drive over 60mph and DO NOT drive for more than a half hour without stopping to let the gears cool for the first 100 miles. Proper initial temperature cycling is critical for long gear life. Do not tow or climb for the first 500 miles. After 500 miles, crack them open and check gear contact again. Replace the oil and you are good to go. Just remember to change the oil again every year.

BTW - With 4.88 and 315/70R17 Duratracs the engine RPMs will be 22% higher than stock 3.73 and P255/70R18 Duelers. This will be optimum for OD on Florida's fairly flat interstates.

BTW2 - If you currently have 3.21 gears, you will also need a new carrier.