I've been reading a lot of these threads, and IF I were to regear, I'd do 4.88. Highway / daily driving is my primary concern. I don't tow, I don't spend my time driving up hills or against the wind, and even at 1900rpm I have yet to see a downshift. I've seen the speed drop 3-4 mph, but that's it. 2300 rpm would be my sweet spot. But being that the difference between that and my 4.10 I'd not that much, my brand new set of half doors is ahead of new gears in my mod roadmap...

 

gears

low is never enough; who gives a s...t about daily driving;it's a jeep not a honda civic;did you buy a jk to go on the highway,well you are a soccer mom then,I bought mine to wheel it!!!! I use my wife civic to go shopping or on the highway.So go with 5.38 and go crawl so rocks you won't regret it

 

low is never enough; who gives a s...t about daily driving;it's a jeep not a honda civic;did you buy a jk to go on the highway,well you are a soccer mom then,I bought mine to wheel it!!!! I use my wife civic to go shopping or on the highway.So go with 5.38 and go crawl so rocks you won't regret it

And THAT is why they make different gears. Different strokes for different folks...

 

Been thinking about this topic for quite some time now and I haven't read one post regretting going with 5.13's. I hope I won't be the first I'm taking "Connie" in for regearing on Monday morning:bounce::bounce:. Sierra 5.13's very affordable and couldn't find anything bad written about them. Wish me luck!

 

5.13s are not enough gear for 35s IMO. So far I'm not at all as happy as I was with 33s. Before I could go up any incline the Texas and Louisiana interstates had to throw at me, with full cargo and five passengers. Now I'm back to constantly downshifting to maintain 75mph on even small in lines. I'd be suicidal if I had put 4.88s in my junk. I'm so sick I'm contemplating going back to a 33-34 inch tire. Do not fear the gear. Do the math, you are talking a tiny bit more rpm to make a world of difference.

 

We Just Installed g2 gears on my 09 rubi, no noise
Install wasn't bad and it's the perfect amount of gears for 37s
I'm turning 3000rpms at 70
Would rather that be alittle less but oh well
Btw it's a manual

 

Ok guys just dropped off Connie for her gear swap to 5.13's at Roco 4X4. I'll let you know how she runs when I pick her up tomorrow. Hope all goes well.

 

Finally got my 5.13's in and I've got to tell you that I'm shocked how well she runs now. I'm really glad I didn't go 4.88 like I was planning to do. It runs really good on the highway too. I can't wait for the break-in so I can pull the camper and see how it does. I expect it will be just fine. Depending on how much highway daily driving you do you could even go 5.38's. By the way if you are local and are looking for a good shop to get work done give Roco 4x4 a call.

 

I had 513"s installed last week on my 2010 Rubi. I run 35"s. This by far is the best thing I have done since I have owned the Jeep. After I lifted it and put on the 35"s it sucked on the freeway. Now it's great. I drove it last night to the bowling alley head on into the winds (15 mph or so) we are getting hear from Hurricane Alex. At 70 mph going up overpasses my Jeep didn't downshift a single time. Hats off to 249 drivetrain for a job well done.

 

Why does Jeep gear these Wranglers so tall from the factory? The Rubi with its 4.10 gears is geared too tall for even the stock 32" tires. Our Rubi with stock gears and tires will turn 2200 RPM at 78 mph, while our Grand Cherokee also with stock gears and tires turns 2700 RPM at 78 mph. Both Jeeps were being driven on the same freeway at the same speed on the same day, my wife was following me in her Grand Cherokee and I called her on her cell phone and asked her how many RPM her Jeep was at.

So why does the RUBICON version of the Wrangler, which is supposed to be the ultimate top of the line OFF ROAD model of Jeep vehicle, have taller (effective) gears than a street only version of a Grand Cherokee? Come on Chrysler, figure it out. The Rubicon should have came with 4.88 gears for the 32" tires it comes with. Or, it shouldn't have such a deep overdrive in the transmission.

 

Two different vehicles should NOT be at the same rpm going down the highway. Why would you think that? Different trans ratios, different ENGINES that have make there power in different rpm ranges. #1 reason why any factory vehicle is geared the way it is is because of the having to meet CARB mpg standards.

 

Actually, I never said two vehicles should be turning the same RPM while going down the highway. What surprised me though, was that a Jeep that is made for street only and has a top speed of 160 mph is wound out more in high gear while driving the speed limit than a Jeep that is made for rock crawling. They do call it the "Rubicon" after all. I expected it to be the other way around, and that the rock crawling Jeep would be turning more RPM.

Why does an off road model like the Rubicon need a deeper overdrive in its transmission than a Jeep that goes 160 mph? Its not like the 3.8 V-6 isn't meant to rev a little bit. So why is the Rubicon (or any Wrangler for that matter) geared so tall on the highway?

Answer: C.A.F.E. ratings are more important than having gearing that would actually work better. I still say the Wrangler is geared too tall, even with stock tires.

 

I just installed 5.13s with 35 toyos MTs,I'm turning 2400 @70mph(GPS)with an auto.IMHO thats what the 3.8 needs to push that brick down the road.

 

Agreed, the Rubi with its 4:1 low range works very well off road. Pretty certain everyone else was talking about high range gearing on the highway though, at least that is what I was talking about.

My Rubi is in the shop this weekend getting 5.38 gears installed. Thats why I'm sitting at home surfing the net, instead of out on the trail doing some exploring. I think the 5.38s will work well for the auto trans and 35" tires it will have .

 

my question is what is the ACTUAL tire size you guys are running?

i've got 35" KM2's on a 17" rim and they measure like a large 33-34" tire.

i'm torn between 4.88's and 5.13's. it's my wife's jeep. 07 X with 4.10's, superchips, and the KM2's. it sees almost no trail time at all, it's all highway/mall crawling. highway is 75mph-80mph regularly in the AM commute.

if it was a true 35 i'd be all over the 5.13's, but these run small.

i'm torn between the 2.

 

I've been running 35 KM2's for 70K miles with 5.13s and love the combo. I've done a TON of highway driving with them and cruise between 70-80 almost all of the time, you will still have some down shift on longer hills with cruise on, which makes me wonder what the 5.38's would be like. 4.88's IMO would be a waste.

 

From all of the reading I've ever done the choice with an AUTOMATIC is 5.13s if you have D30/D44 and 5.38s if you have D44/D44 (Rubi).

I am going 5.13s in our 4 door auto when I regear it and put it back up on 35s sometime this year.

For comparison, I have a 6 speed two door on 35" MTRs (real 35s) that gets better mileage when I don't use 6th gear. It has 3.73s right now. 6th gear works, but it slugs ALOT.

 

i am going with a g2 5.13 gears in a 4 door with auto... 35's ...i got a killer deal from a guy who sold his jeep..brand new in boxes $200 for front and rear....
i think when you add winch+ bumper rear spare tire and bumper,rocksliders, jerry cans, hilift and mount,tool box, hardtop....cooler full of frosty beverages, camping gear, 1 fat girl or 3 skinny ones...it seems they are the best choice 5.13's. put it this way we just changed the weight to a surburban.
and with an added computer flasher of your choice to edit your tire size and gear ratio...you will be good.
great info on here nice chart
dont forget your gauge pod for your tranny temp
www.jkgaugepods.com

 

i love my 5.13 on 37's. i never reprogramed the computer/spedo and i dont see excessive downshifting except when going up a long steady hill. dont expect to go faster than 70 without realy givin it some gass. go with 5.13 you will love it