Do Yourself a Favor and Regear Your
2012-Up Jeep JK Wrangler

When we bought our 2012 Jeep JK Wrangler, we had always planned to upgrade it’s axles to a set of Dynatrac ProRock 60’s. Of course, being that money doesn’t grow on trees, we decided to use the time until we could afford the upgrade to extensively test just how well a set of 37″ tires would do with the new 3.6L Pentastar motor running factory 4.10 gears. For almost 2 years, we took our Jeep just about everywhere we could, driving it to and from the trail, on the highway and around town, up and over mountains, hard and fast through the Mojave Desert, up and over steep ledges in Moab and, crawling it over big rocks on trails like the Rubicon. And, after racking up over 45,000 miles on the odometer, what I can tell you is this… it can be done and it does work surprisingly, okay. For someone who’s never driven a re-geared equivalent, they may not even know what they’re missing.

Having said all that, recent circumstances forced us to upgrade our front axle sooner than we had planned for and, while we were at it, decided to just bite the bullet, take advantage of Off Road Evolution’s $999 special and have our Jeep re-geared with a set of 5.13’s at the same time. After testing them out extensively on the 2013 JK-Experience, all I can say is - why in the hell didn’t we do this sooner!!

While the 3.6L motor has a good amount of power and will do a decent job of compensating for larger tires, it simply can’t make up enough of a difference especially in situations like on long or steep hill climbs. Here, your transmission will try to help make up the difference by dropping gears and running your RPM’s up close to 6 grand just to keep you moving. Of course, this will cause your engine and transmission to run really hot and in some cases, cause your Jeep to go into limp mode - ask me how I know. With a set of 5.13’s, this will no longer be an issue as you’ll have plenty of power to do the same job in a higher gear and running at a lower RPM. Of course, this is to say nothing about the fact that on the rocks, a set of 5.13’s will also significantly improve your crawl ratio - running 37″ tires on 4:10 gears, you’ll go from a 3.36:1 to a full 4.21:1! Of course, for those would might complain about the increase in RPM at highway speeds, what I can tell you is that it’s really insignificant. In fact, the difference you’ll see when compared to a stock Rubicon running 32″ tires and 4.10 gears is only about 200 RPM as you can see in the calculators below:

Trust me, if you’re planning on running 35″, 37″ or bigger tires on your 2012-Up JK, you really will be doing yourself a BIG favor to get it re-geared at the same time. If you live in the SoCal area, be sure to take advantage of Off Road Evolutions $999 special too as it really is a deal that is hard to beat.

14 Comments so far

  1. Brad September 17th, 2013 1:15 pm

    You have convinced me! did you see any improvement in mpgs after the regear?

  2. rays0852 September 17th, 2013 3:48 pm

    I am assuming you are running a 6 spd? I have 4.10s and an Auto on my 2012 with 35s and its perfect. Call me crazy but I think 2865 RPMs on road trips is too much for too long.

  3. wayoflife September 20th, 2013 12:22 pm

    Brad, around town, yes. There is less effort needed to get you going. On the highway, we’re now pushing a bit more RPM higher at highway speeds so no.

  4. wayoflife September 20th, 2013 12:23 pm

    ray, I am running an auto. 35’s and 4.10’s is a good combination. We are running 37’s.

  5. Mike December 16th, 2013 12:09 pm

    I was curious if you had done any kind of upgrades to the rubicon axles like c gussets or truss’ or anything of that sort? Also did you break anything, or have to replace anything due to premature failure?

  6. wayoflife December 20th, 2013 2:11 am

    We are running a Dynatrac ProRock 44. I personally wouldn’t waste any money beefing up a factory Rubicon front axle as it’s really just a Dana 30 with 44 center section. If anything, upgrade your shafts to chromoly with full circle clips and maybe gussets but that’s about it.

  7. n3tfury January 27th, 2014 12:17 am

    Need some advice please: My budget won’t allow the re-gear on my 2012 Auto with 3.73’s for another 6 months. I want to go straight to 37’s, MC 3.5 lift, cut my fenders, strengthen the front axle (C gussets and sleeves), but my regear needs to wait. Is that do-able without any hardcore offroading and Arizona flat roads?

  8. Clark April 28th, 2014 9:37 am

    Eddie: You have had extensive experience with the 3.8 and now the 3.6 Jeeps. I have a 2010 JKUx with the auto and 3.73 gears on 33s. I’ve been thinking about possibly regearing for 35s and adding lockers or possibly upgrading to a new Rubi. If I got the Rubi I would not want to have to regear for 35s for primarily overlanding type use, but some intermediate rock crawling. It is also my daily driver, but I don’t have a commute as I’m retired. What are your thoughts comparing a regeared 3.8 to a 3.6 Rubi?

  9. wayoflife April 28th, 2014 10:40 am

    If it were me, I would get a new Rubi with a 3.6L motor. It really is that much better of a motor. However, if money is an issue, regearing your 2010 to 4.88 will help bring your performance back to about stock with a set of 35’s. 5.13’s will give you a boost in power but will leave your dana 30 pinion very small and a weak point.

  10. William May 4th, 2014 9:11 pm

    Hi, I have a 2013 JKU Sahara with 3.21 ratio. 3.5 rock krawler lift TN front and rear drive shaft and OMEmu steering… I been running 35’s on 18″wheels for over a year without problem but I just recently bought a rear 44 arb air locker …. Now my friends are telling me I need go regear both front and rear also due to the “max tow” option (although I don’t have it) the front differential needs to be changed completely for regear other wise it will blow…. Any thoughts on the regear ? If so what ratio? 3.73?4.10? It’s also my DD… :)

  11. reelget May 8th, 2014 9:49 am

    I just bought a 2012 JK w 35’s 3.5 lift but i’m guessing stock gears. need advice on which way to go with gearing for street and mud use more than climbing .. my question is can I get by with axel sleves and upgraded axels .and locker on my dana 30 to suit my needs and rely on the 30 … plus upgrading rear 44 as well ?

  12. wayoflife May 10th, 2014 7:34 pm

    Is it safe to assume you don’t have a Rubicon with 4.10 gears? If you do, you should be fine. If not, I might recommend 4.88 gears. 4.56 will bring you back up to stock but 4.88 will give you just a bit more power. No need for sleeves, just gussets.

  13. James July 24th, 2014 11:31 am

    When you ran the stock setup with the 37s for nearly two years, did you make any drive shaft modifications?

  14. wayoflife August 3rd, 2014 10:51 am

    Yes, I upgraded my shafts to a set of JE Reel 1350’s. However, you can get by with just upgrading your front shaft and running a factory rear so long as you have a 4-door.

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