makod

Looking for advise on ordering a new Wrangler Unlimited Automatic and the issue of gearing (not sure if ever discussed before)

For a daily driver, mostly highway (70 MPH) with weekend hunting/fishing trips, and to plow my long driveway keeping in mind the cost of gas and MPG.

Order 3.21 or 3.73s?

I have no plans what so ever of installing 33-35 inch tires etc. just don't want to get burnt on poor performance with the 4-door and an automatic but on the other hand don't want low (by Jeep standards) MPG.

There are a lot of opinions out there but as long as the 3.73s are say 2-3 MPG worst than the 2.31's I'll be happy.

Ordering this Thursday and this choice is driving me crazy.

BossHog

3.73s. Minimal up charge and it will afford you more options down the road.

jadmt

I have a 13 jku with 3.21's auto and 285/75-16 tires ~33" and I do not rock crawl and probably never will and the 3.21's do incredibley good for light off roading and great on the highway and in town. I get 20 + on the highway and never less then 16 hand figured in town in the winter. It has warmed up a bit and now we have summer gas and my back and forth to work average was over 18mpg hand figured. My speedo and odometer are spot on and calibrated with a procal.

rob_engineer

This comes up maybe once per week on here. I would say well over 95% of responses to this question side on getting the 3.73, particularly if you ever will consider towing anything or going with bigger tires. I had to order mine because nobody within 100 miles at the time had anything other than the. 3.21. I love my 3.73 and have towed a trailer weighing around 4500 pounds. Some complaints I have read about 3.21 are more hunting of gears on hilly areas and the 6th gear in manuals being pretty useless. Go with 3.73- you won't regret it. MPG penalty is almost non existent.

RescueGreen#3

JKU auto with 3:21 ?!?!?!?

Noooooooooo!

Look at the Internet over the last 6 years, a heavy JKU with 3:21 and an automatic transmission? No way. Bad idea.

If you are concerned about the mpg and the tiny tiny difference it will make in regards to the gearing of a 5,000+ pound giant brick, might be time to look at a different vehicle. It's not the gearing which causes poor gas mileage in a JKU, it's the fact it's HEAVY, boxy, and as aerodynamic as a turd without fiber!


If you are ordering, certainly get the 3:73 gearing.

furndoc1

3.21s are for cars not jeeps. get the 3.73s I just got rid of a 2007 with 4.10s and wish it was available on my new Sahara2013 which I ordered with 3.73s. It pulls great on the hwy and also needs to pull a trailer in the summer with 2 4 wheelers . If you are worried about fuel mileage buy an electric scooter. Its a Jeep thing.

Desert Fox

1. I have been off roading for about 50 years, and have owned three new Wranglers since 1998. I currently have a stock 2012 JKU Sahara with auto and 3.73 R&P gears. Why?
2. Owning a JK is very much like owning a Swiss Army Knife. In addition to performing the traditional roles of a family car, it is a vehicle that can be used to go many places, and do many things, that other vehicles can't. It may not do all things equally well, but it still provides you with a high degree of utility in your life that non-JK owners will never know.
3. There are many versions of the Swiss Army Knife. There are specific models for golfing, fishing, camping, sailing, etc. etc. There are also many utility versions that try to anticipate every need that its owner may encounter, but seldom do. There is even a version that costs several thousand dollars that you would have to hire a Sherpa to carry around for you.
4. In many ways buying a JK is much the same as purchasing a Swiss Army Knife. You can go the very specific route and get a Rubicon which is very good off road but at the expense of mileage and to a lesser extent overall comfort. Or, if your are a mileage nut, you can buy a Sport with 3.21 gears, street tires and a 6 gear manual which will result in better mileage but at the expense of off road performance. (If this is your goal, may I suggest a Prius)
5. The real challenge is faced by the potential JK buyer who "wants it all." If you want family car convenience, get the 4 door "U" version. If you want your wife to drive it with a car full of screaming kids, may I suggest the auto tranny. But if you want to occasionally go off road on a local fire trail and not worry about it, get the 3.73 gearing, A/T tires and the rear D44 with the Limited Slip Differential. This will give you a recreational off road capability but stay away from rock gardens and mud.
6. To answer your specific question - get the 3.73 R&P gears. There will be minimal affect of mileage with an auto tranny and it will perform better off road and would will be able to tow a small trailer.

FDHog

I bought a 13 JK 6spd with 3:21 gears. Because of my color selection and minimal options I wanted, any available Dozer with 3:73's was about 4k more.
I hate the 3:21's. the gearing sucks for hilly areas.
Like you, it is my DD, and used for access to the beach for surf casting.
In about a week, I'm getting 3:73's and a Detroit Truetrac (rear), and I'm still coming out cheaper. I don't plan on anything larger than 32's, and I want an all purpose Jeep.
I had a 97 with 3:73's, and a 2005 Rubi with 4:10's. the 3:73 are by far the best all-around gears.
Gas mileage.........I get my best mpg when I'm around 2000-2200 rpm. Anything lower, and theres just no power. With the 3:21's, that's almost impossible on the highway.

wrigley

There's not that big of split in MPG. Get the 3:73 you'll be glad you did in the long run! Good Luck!

Mike

JKSahara12

Look I have a 2012 JKU Sahara with 3.21 and I do a little off roading not much and it's my wife dd and I have pulled a 14' flat bed heavy duty trailer with a little weight on it and have no problems at all I love my JKU but for better performance 3.73 would be a better choice so it's all in opinion honestly