I have a 2012 unlimited (not a rubicon) with 33's and a 2inch lift. I believe I have 321's and 6th gear has become basically useless unless on flat terrain. I would like to get the best fuel eco. Keep the 321's or go 373 or 401? Thanks!

 

oops I forgot, I would like to use 6th gear again for those highway mountain miles and I dont do hardcore crawlin.

 

For performance I would go with 4.56 gears tops.

 

Eco I would say 4.10.

 

I second the 4.10's. You only have 33's so a 4.10 would basically push your ratio towards what 35'-37's would be with 5.13-.38's, and you said you don't really go offroading much I guess, which means you're aiming for more economy right? And Stock Dana 30 axles aren't that strong so the higher you go, the more likely you'll break something without either reinforcing them or just upgrading altogether...

 

Go to 4lo.com and play with the numbers on their gear calulator. I would always go at least one step lower for more power.

 

4.10's seem to be an all around good compromise. My 2007 has 4.10's with my 33's. I am happy with that. Great off road, pretty decent mpg on road. (For a jeep.)

 

I agree with the 4.10s. My Rubicon has 32s out of the box, the extra inch will not be an issue. I'll be running 35s with the 4.10s and expect it to be just fine.

 

I've got a '12 JKUR auto and am running 35" BFG KM2s with 4.10s. Runs good but could be better, especially with stop and go city driving.

Needless to say, after driving it this way for 3 months, it's going to the shop next week to have 4.88s installed.

 

Interested to see how this turns out for you. Definitely post how it runs.