I have a 2013 JKU. Currently with the stock 3.73 gears, 3.6L, auto. Running 34" Duratracs. This is strictly a daily driver as I have a dedicated 76 bronco for my trail truck. It is just Ok... with the stock gearing, but I have decided that I am going to bite the bullet and regear.

The gear chart shows that 4.10s would put me back in optimal gearing, but of course, 4.10s are more expensive and harder to come by. 4.56s are certainly an option, but I am concerned that this will gear me to low and will affect gas mileage. It is already not very good.

Anyway, interested in feedback from others with the same setup ( 2012+ 3.6L only). Much of the driving is at freeway speeds, BTW

Thanks in advance

The other option is trade it in for a Rubicon ( which I should have bought in the 1st place!)

 

If you are doing a lot of highway/long disctance driving then the lower gearing will probably hurt mpg a bit more than running the 4.10's. You will be at higher average RPM's so... However, if you are driving a lot of city and/or highway driving that is very hilly then the lower gearing won;t make much of a difference.

If you have any plans to go bigger on tires then the 4.56's are probably a better choice. And if you ever plan of wheeling your Jeep (which i know you said you don;t right now), the lower gearing will help with any crawling you may do.

if you are having issues finding 4.10's that are priced similar to all the kits out there for 4.56, 4.88 and 5.13, then you might look in the for sale section as stock 4.10's pop up from time to time. hell, I gave my stock ones away when I moved to 5.13's (3.8 engine) and they only had about 6K on them.

 

I guess I am looking for someone with a similar setup to mine with 4.56s to tell me what thier experience was.

I have a set of take out 4.10s from a buddy. These came from his 2012 Rubicon. I was thinking that I could use the rear ring and pinion, but I am thinking that they are actually different than the non Rubicon gears. Can anyone confirm that?

Again, I have a dedicated rock crawler, so this will never see any ofroad action.

 

I have 4.56 and still run 32" tires for now. I like the gearing a LOT! Yes, it gets 1 or 2 fewer MPG but it is waaaay nicer to drive. The new tires will be an inch or two bigger, which should still be OK with the 4.56.

I might have tried the 4.88 but with a front D30 I did not want the front pinion to be so puny.

BTW, I lost more MPG going from SRA tires to MT tires than I did by going from 3.73 to 4.56.

 

I will speak to my experience, although it is probably contrary to what most others would say. I say go with 4.10 gear.

Mine is '13 JKU sport, so 3.6 with Automatic. My tire size is 315/70R17 Kelly TSR, comparable to the duratracs.

I tried both 4.56 and 4.10. ( I DIY my own, so labor cost are not there, but wasn't happy buying extra parts) I originally started out with 3.73. Then I swapped to 4.56. It revved pretty good on the highway. I don't recall exact numbers, but highway mileage went down and city mileage went up as compared to 3.73. Thought it was weird when I get better mileage driving in town vs highway. On the highway the engine didn't sound like there was any load on it.

Then I put 4.10 in. That seemed like the sweet spot to me. 2450 rpm on the highway. Engine sounded like it had a load on it, but not overloaded. The city/highway fuel mileage numbers were more balanced out. Mileage number are not much different that 3.73, at least on my vehicle.

The gear charts seem to be right on. If you have 3.73 and mostly highway drive, shift it into 4th gear..that will be the engine rpm when you are done if you regear to 4.56 (5th gear). If you like it go with it.

 

If you find used 4:10s, the fronts will most likely be for a Dana 44, because 4:10s are only an option on the rubicon. Not to say that someone didn't regear their non rubicon to 4:10s and looking to get rid of them.

 

I'd say 4.10 if only a DD. I run 37s and 4.88, but would have been just as happy with 4.56. 4.56 on 34/35 tires will rev pretty high on the highway (like my setup does). Unless you live in a place like Colorado, the 4.10 will be a good fit. My dad runs 4.10 and 35" nitto trail grapplers and it feels perfect. If you start to wheel it more and want more low range, just swap in a Rubi transfer case.