Time for new tires and gears.

Super Dave

Super Dave

New member
Hey guys I'd like to get your input on my next upgrade. I'm running a 2014 Rubicon Unlimited with a 3 and 1/2 in J spec lift, I'm wanting to put on 37 inch Open Country RT tires with a new set of gears. First initial thought was 4.88 then I was suggested 5.13 and now it seems I'm reading a lot about 5.38. I don't use my jeep as my daily driver, it only has 20k miles *on it but I do travel up to four to five hours to hit a trails. Also should I consider C gussets or any additional items I may be overlooking by going to 37s like brakes?

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Super Dave said:
Hey guys I'd like to get your input on my next upgrade. I'm running a 2014 Rubicon Unlimited with a 3 and 1/2 in J spec lift, I'm wanting to put on 37 inch Open Country RT tires with a new set of gears. First initial thought was 4.88 then I was suggested 5.13 and now it seems I'm reading a lot about 5.38. I don't use my jeep as my daily driver, it only has 20k miles *on it but I do travel up to four to five hours to hit a trails. Also should I consider C gussets or any additional items I may be overlooking by going to 37s like brakes?

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Don't go lower than 5.13 on factory axles. The pinion gear gets too small and will snap if you play hard.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407
 
If you are going to 37s I would recommend a big brake kit. And as James says, better to avoid a 5.38 in a 44. You can find some gear charts online to help you with the choice. There are different ones for AT and MT, and 3.8 v. 3.6, so make sure you look at the right one.
 
No doubt you may have just seen this video. In it, Rubicat is running 5.38 gears in a 44.

https://youtu.be/NsfZlyGNcyI

You can do it, and it would be all right, but according to Wayoflife, he would run 5.13 with 37 inch tires, and 5.38 with 40’s. Weld on some c gussets, and have fun until it breaks.


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notnalc68 said:
No doubt you may have just seen this video. In it, Rubicat is running 5.38 gears in a 44.

https://youtu.be/NsfZlyGNcyI

You can do it, and it would be all right, but according to Wayoflife, he would run 5.13 with 37 inch tires, and 5.38 with 40’s. Weld on some c gussets, and have fun until it breaks.


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Running a 5.38 only in the PR44 front. Had a 60FF rear. The issue with a 5.38 in a 44 is similar to the issue with a 5.13 in a D30: the pinion is very small and therefore prone to failure. Could it be done? Sure. Advisable? Probably not.
 
fiend said:
Running a 5.38 only in the PR44 front. Had a 60FF rear. The issue with a 5.38 in a 44 is similar to the issue with a 5.13 in a D30: the pinion is very small and therefore prone to failure. Could it be done? Sure. Advisable? Probably not.
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It was done, and successfully, but as I mentioned, he thinks 5.13 is the perfect ratio for 37’s, and has directly told me so.


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So I was sold on the 5.13 until I seen that video and build out on the credits. That's where. I started looking at forums around the 5.38, which threw me for a loop. I hoping to do the one and done with gears or until Somthing breaks. I just don't want to kick my self in the ass and start swapping out good parts.

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5.38 is NOT a gear I would recommend in a 44 and for the reasons mentioned. We ran them in our ProRock 44 but only because that's what we had in Moby's old ProRock 60 and became Rubicat's hand-me-down. We knew we'd be upgrading to a 60 up front sooner or later. For 37's, 5.13 is a better ratio regardless. At least, in my opinion.
 
wayoflife said:
5.38 is NOT a gear I would recommend in a 44 and for the reasons mentioned. We ran them in our ProRock 44 but only because that's what we had in Moby's old ProRock 60 and became Rubicat's hand-me-down. We knew we'd be upgrading to a 60 up front sooner or later. For 37's, 5.13 is a better ratio regardless. At least, in my opinion. But, hey what do I know I'm a Mall Crawler!!!
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Eddie, fixed your post :cheesy::cheesy::cheesy:
 
What are your thoughts on 4.88 vs 5.13 with 37" tires if doing a lot of hwy miles? I was all set with going 5.13 then a lot of locals were telling me not to go so deep if I was going to be traveling long distances. I am looking at doing the PR60s and would rather not regret my gear choice. :thinking: However, we do a lot of long trips.
 
jorgelrod said:
Eddie, fixed your post :cheesy::cheesy::cheesy:
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:cheesy:

stitch1 said:
What are your thoughts on 4.88 vs 5.13 with 37" tires if doing a lot of hwy miles? I was all set with going 5.13 then a lot of locals were telling me not to go so deep if I was going to be traveling long distances. I am looking at doing the PR60s and would rather not regret my gear choice. :thinking: However, we do a lot of long trips.
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With a 3.6L motor and an automatic, I still say 5.13's. If you can, find someone who's running 4.88 and 37s and someone running 5.13 and 37s. Your locals can talk all they want but unless they've driven both setups, all they can do is talk. With a 6-speed, 4.88 is what I might consider based on what you're wanting.
 
I ran 4:88's originally and went to 5:13's when I swapped axles. There is only a 200 or so RPM difference between the two at highway speeds. I personally like the better low end that the 5:13's give you. But be honest with yourself. If you are doing mostly highway and on-road driving maybe the 4:88's are a little better for mileage reasons. But if you do any offroading I would highly suggest the 5:13's.

Edit: I'm also running the 3.6/auto
 
I’m running 4.88 with 3.6motor on 37s. With the 4.1 transfer case it does just fine on the rocks but is still solid at highway speeds. I get about 13MPG avg. no complaints.


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Samuelh3 said:
I’m running 4.88 with 3.6motor on 37s. With the 4.1 transfer case it does just fine on the rocks but is still solid at highway speeds. I get about 13MPG avg. no complaints.
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I'm in the same boat. You can always downshift when you need more power to pass on the freeway.

But I do think it depends on where you live. If you're doing most of your driving where it may have more rolling hills, shifting may get to be a pain so having more low-end might be the way to go.
 
:crazyeyes: Sounds as clear as mud. lol Seems every other post goes back and forth. Everyone around here with a 3.6 has either 4.56 with 35s or 4.88 with 37s. Anyone running bigger than that is in an older rig that is pulled on a trailer everywhere. Only people I know going deeper are the 3.8L guys.

I'll probably just stick with the 5.13 idea.
 
stitch1 said:
:crazyeyes: Sounds as clear as mud. lol Seems every other post goes back and forth. Everyone around here with a 3.6 has either 4.56 with 35s or 4.88 with 37s. Anyone running bigger than that is in an older rig that is pulled on a trailer everywhere. Only people I know going deeper are the 3.8L guys.

I'll probably just stick with the 5.13 idea.
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I don't want to get to the point where I have to tow my rig to play family n the hills. If I'm towing my jeep I would like to pull it behind an class A motor home but still functional for getting around. 37 will more than likely be to biggest set of tires I put on my jeep.

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Went through this same decision process a few months ago , back and forth with the 4.88 vs 5.13 decision.... Installed PR60's with 37" Nitto Ridge Grapplers and ultimately decided on 4.88s...... this was even after talking with Steve at Dynatrac who talked me back into the 4.88s after I called to change my order to 5.13s.... honestly even with my Heavy jeep, it now drives great once I finally got my alignment dialed in. Haven't totally loaded it down but I feel I have more power now then I did before. Took an hour highway drive with some stop and go this past weekend and after 70 miles per the jeeps info mpg reader, jeep was stating 15.3 mpg... BTW I have a 3.6 16 JKUR....
I also recently installed a Pedal Commander and boy did it make a big difference in my throttle response, made my jeep more fun to drive... BTW I have no affiliation with the company, just throwing that out there.

So with all that said, I also have never driven a jeep with 37s and 5.13s so don't have a comparision but at this point I have no regrets... but we will see how it goes when I hook up the Overland trailer.
 
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