2012 JK Sport 2 Door Overland Build

[Justincredible]

I have a 2012 2 door automatic Rubicon that I bought used with a 2.5" Teraflex lift and 35" Nitto Trail Grapplers. It has 4:10 gears and the 3.6 liter which has plenty of power with this set up (of course I also have the rubicon transfer case which is geared much lower). The shift points were off when I purchased it and then I got a Super Chips Flash Paq which adjusted the shift points and corrected the speed odometer. I am pretty sure that with 33" tires you cold probably get away with 3.73 gears with the 3.6 liter engine especially if your Jeep is a daily driver.

As far as upgrading gears a economical way to do it would be to pick up someone's stock 3.73 or 4.10 gears when they upgrade. The stock 3.73 gears that come with the towing package also have a limited slip in the rear differential.

My '12 on 33" tires is downright spritely to me with 3.73 gears (also no rear LSD). Especially when compared to my old '02 Wrangler with the 4.0 or my '02 Xterra.

 

[Kmrtnsn]

OP, you keep saying the tires you currently have are 31". What do the little numbers on the sidewalls say?

 

[Kmrtnsn]

Gearing also depends on your altitude. Where do you live?

The western mountain states like Colorado and Utah (4000 - 14000 ft elevation) require much lower gearing (numerically higher) due to the horsepower loss of a naturally aspirated engine (3% loss / 1000 ft above sea level). The 285hp Pentastar V6 is only 240hp here in Denver, and less than 200hp climbing over Vail Pass. With 33" tires, my 3.73 gears are just adequate in my opinion for here in Colorado.

Back east where elevation is rarely above 1000 ft, it seems many are perfectly happy with 35" tires and 3.73 gears.

Exactly! I'm sick of hearing that "35" tires are just fine with 3.21s" from Jeepers in Florida and Texas. Or, "I'm running 35"s on 3.21s and a manual, I've lost use of 6th gear but it's fine". Really? No OD highway gear and it's "fine"? Take that flatlander "just fine" stuff up Poughkeepsie Gulch and tell me how fine it after you cross over California Pass.

 

[BCobe]

How are you liking the AEV lift? Trying to decide between this one or an OME one.

 

[JPontheMountain]

OP, you keep saying the tires you currently have are 31". What do the little numbers on the sidewalls say?

They read: 285/75 R16 126/123Q 10PR

When I asked the shop, they said it was about a 31

 

[codesertrat]

They read: 285/75 R16 126/123Q 10PR

When I asked the shop, they said it was about a 31

Hmmm. That shop doesnt seem to understand metric tire sizing - a 285/75R16 is about a 33" tall x 11" wide tire.

 

[JPontheMountain]

Hmmm. That shop doesnt seem to understand metric tire sizing - a 285/75R16 is about a 33" tall x 11" wide tire.

I'm pretty sure it was the guy at the desk when I dropped it off that said 31". They are definitely 33". Thanks for the clarification.

 

[JPontheMountain]

Got a few updates:

After doing my homework, I'll likely be upgrading to 4.56 gears after my tire change (within the next two weeks) sounds like that will be optimal for where I live (Salt Lake City) and what I'm planning to do with the vehicle.

Rear bumper, tire carrier, and IPF backup light all installed. The IPF light mounts a bit crooked. It bothers the crap out of me that it's not straight. I'm thinking I'll have to get a small piece of sheet metal under the left side of its mount to straighten it out.

Also, after a straight month of scouring local classifieds, I finally found and purchased a pair of Rubicon rock rails and installed them today.

Lastly, SAVEGRES!!! Next up, 35" BFG KM2s, black Savegre's, and fuel caddy.

 

[Kmrtnsn]

I'm pretty sure it was the guy at the desk when I dropped it off that said 31". They are definitely 33". Thanks for the clarification.

Exactly why I asked. You already have essentially the idea overlanding tire for your gearing.

 

[JPontheMountain]

Was able to get the savegre's, tires, and fuel caddy on late this week. decided to head straight for the mountains for a quick trip. The wheels/tires change the entire look of the jeep! I'm so glad to be rid of that chrome!

 

[BCobe]

Hows it running with the 35s?

 

[JPontheMountain]

Hows it running with the 35s?

Surprisingly, really really well. Shift points and speedometer is off, but I've got a procal in the mail. I've noticed a small power loss when climbing uphill, so eventually I'll want to upgrade gears. First, front bumper and winch.

 

[JPontheMountain]

Front end complete. Put a Xeon 10-S on rather than the originally planned 9.5cti-s.

 

[swoope18]

Once you get the gears in you will understand why everyone was asking about it.

To me most people forgo gears as its a mod you can't see.


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[JPontheMountain]

Once again out get the gears in you will understand why everyone was asking about it.

To me most people forgo gears as its a mod you can't see.


Sent from my iPad using Tapatalk

All part of the plan. Hopefully changing gears in the next few weeks.