HI ALL, ok i have read and re-read opinions, I would love feedback from JKUR owners with automatics. I am about to regear my new JKUR. I will be running 37s with the slightest possibility of going down to 35s in the future. It will be a daily driver more than it wont be. I am thinking of going with 5.13s OR 4.88s. It came with 4.10s luckily and not 3.73s. I know i can get away with stock gears. The drive to work never exceeds 55mph, but would like to be able to travel in the JKUR and not get 10mpg, as i am currently getting 18mpg. Has anyone done 4.88s and hated it ,went with 5.13s, or the other way around? Thanks for yor opinions.

 

I just put 35's on my 2013, it is an auto with 4:10's , I thought I would have to re-gear, but after I got my AEV procal tuner, adjusted my shift points, and BAM! It runs great! Not re-gearing I dont know about the 37's , try the procal first!

One more note: I too was getting 18mph with stock wheels, aftert the 35's and AEV procal im getting 17.4

 

^^^^^this

I have a 2012 auto with 3.21s and 35 KMs. I re gearing. I am trying to decide between 4.10s (ideal gear but more expensive) or 4.56s ( more hear than I need, but less $$$).

Many people are discovering that 35s with 4.10s on a 2012+ is ideal. 37s you will be fine. A guy in my club runs that setup and will not re gear. Matt GT on the forum also runs 4.10s and 37s and thinks its fine.

Go with the 37s and see if you like it. I think 4.88s and auto is way to much gear.

Talk to other who actually have a late model JK and auto. That way you can see from real world experience what you should do.

FYI.....4.10s with a 35" KM2 will run exactly 2500rpms at 70mph.

 

I'm running 4.88s on my 13 JKUR auto with 37s. Runs about 2800 rpms at 70mph in OD. 4.10s were tolerable on the highway but In my opinion the 4.88s are ideal. I wouldn't think of 5.13 unless you are going bigger than 37s. You will need a Procal to change your settings or you will go into limp mode after a gear swap

 

A wise choice would be to get the tires and drive it for a while and see what you think. Then go from there. My non-first-hand opinion is it will be tolerable/acceptable with 4.10's, but 4.88's would get it back to the stockish feel.

 

I did 4.88s with my 37s. If your doing more highway driving...4.56s may be good. Love my 4.88s though.

 

If its mostly going to be a daily driver and possibly move down to 35s, my suggestion would be to save your $$$ for other mods and keep the 4.10s. With the 4:1 transfer case in the Rubis, you will have more than sufficient crawl ratio offroad with 37s or 35s. I have a 2012 Sahara that came with 3.21s, so when I went to 35s I regeared to 4.56s. As one of the other posts mentioned, get your tires and a procal and see how that works for you. 4.88s are too low for 2012+ that are more of a daily driver, 4.56s are ideally perfect for 35s or 37s and you really wouldn't gain much jumping from 4.10 to 4.56. Best of luck with whatever you decide

 

Great info and opinions, thanks. I just sold my TJ that had longarms, coilovers and was geared, mostly built as a crawler so NOT regearing is difficult to wrap my head around. I had 4.56s in the TJ but only 35s and it was perfect. With this new engine and 4to1 off road should be fun, but after 37s i may change my mind and regear. Money for parts isnt a problem, i have the synergy 3" phase 3 lift , wheels,etc on the way. I do like the idea of going with a procal and trying it out with 410s. This JKUR wont be a crawler for at least a couple years, but id like it to be plenty capable if the mood strikes lol. Any opinions on a "tuner" like a bullydog or is that mainly after people buy a RIPP or stuff in a Hemi? I will not be doing either.

 

My opinion. Tuners for a 2012 + will net you better throttle response....that's it. The drive train in the JKs is a power sucker. The Pentastar is not going to yield more power without a custom tune or forced induction...IMO.

Again....looking back to previous versions of Jeeps you can learn a lot, but when it comes to the engine and gears, this is a completely different animal.

I'm not knocking anyone's mod choices, but lets just say I'm not convinced that tuners, exhaust, intakes, throttle body spacers, ram air snorkels, etc add anywhere near what the manufacturers claim. Even on 2007-2011s.

 

Im not flaming on anyone either or doggin anyones choices but i did the CAI and exhaust and throttle body spacer on the TJ, IMO and actual experience it was a gain of 1hp per $300 and a waste of money, so none of that will be done on the JK unless there is data out there proving otherwise ex: dyno . I will go with the procal for now.