Concerns with 488’s and 37’s.

Hilop

Hilop

Caught the Bug
Hello, I just moved up to 37’s and had a couple questions about my 488 gearing. I have a 13 JKU sport with Rubi 44’s front and rear, draglink flip and Trackbar relocation.

1) Will I be ok rock crawling any of the tougher trails in Big bear and comparable trails in Moab.
2) What mods should I do to my drivetrain to ease the stress on my transfer case since I don’t have the preferred 513 rock crawling gearing?

Please help me put my mind at ease, I think I might be overthinking it.
Any info is appreciated.
Thanks
 
Assuming you have a Dana 30 up front, 4.88 will have a stronger pinion and probably what I would run because of it. 5.13 would be a better ratio to have with 37's but you'd have a weaker pinion.
 
Hilop said:
...I have a 13 JKU sport with Rubi 44’s front and rear...
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I'm running 5.13s with 37s and at times it feels slightly over geared like when I'm on the freeway. On the rocks it's great especially with a 4:1TC. I think 4.88s are probably more manageable in an every day driver. You'll most likely be fine up in Big Bear and Moab however I would stay off the skinny pedal when possible.
 
It's a 136 rpm difference at 70mph between 4.88 and 5.13. I think you'll be fine. I'm on 4.88's.
 
I run that setup and I could not be happier with it. Great on the highway and on the rocks. From my understanding of it, really there is only a small difference between the 4:88 to the 5:13. You made a great choice, you’ll be fine.


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I ran 4.88s with 37s on a 16 rubi 4 door and was generally happy except On Highway long grades. This time around I’ll certainly go 5.13s as it’s not a daily. If you have 4.88s now I wouldn’t change, as I was generally pleased and it was great on the Rocks.


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Hilop said:
Hello, I just moved up to 37’s and had a couple questions about my 488 gearing. I have a 13 JKU sport with Rubi 44’s front and rear, draglink flip and Trackbar relocation.

1) Will I be ok rock crawling any of the tougher trails in Big bear and comparable trails in Moab.
2) What mods should I do to my drivetrain to ease the stress on my transfer case since I don’t have the preferred 513 rock crawling gearing?

Please help me put my mind at ease, I think I might be overthinking it.
Any info is appreciated.
Thanks
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Not sure what lift you may have but as far as easing the stress on your drivetrain maybe take a look at aftermarket driveshafts. Never hurts to have double cardan shafts with proper pinion angle.
 
benatc1 said:
I ran 4.88s with 37s on a 16 rubi 4 door and was generally happy except On Highway long grades. This time around I’ll certainly go 5.13s as it’s not a daily. If you have 4.88s now I wouldn’t change, as I was generally pleased and it was great on the Rocks.


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What happened on long highway grades? I’ve got 37s and wanting to go 5.13s but people keep saying to go 4.88s since it is a daily driver.


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pop2tu said:
What happened on long highway grades? I’ve got 37s and wanting to go 5.13s but people keep saying to go 4.88s since it is a daily driver.


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Just a lot of downshifting and searching for gears. North out of Reno to my house there is a 5 or so mile long grade that you go up 1000- 1200 feet id say. Every day it was shifting down to 4th or 3rd to keep 70-75, which made the engine run hot. I had a procal programmed too, it would go as fast as I’d want it to up the hill just shifted a lot. 4.88s are definitely good for daily driving but if you want more “power” is go with the 5.13s, though the pinion would be smaller, lots of people run the 5.13s with 37s without issue.


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benatc1 said:
Just a lot of downshifting and searching for gears. North out of Reno to my house there is a 5 or so mile long grade that you go up 1000- 1200 feet id say. Every day it was shifting down to 4th or 3rd to keep 70-75, which made the engine run hot.
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This happens with 5:13's as well, or at least from my experience.
I'm actually the opposite, I have 5:13's now and if I had to do it over again I'd go 4:88's.
Mines not a daily either, but I don't trailer it to the trails. 5:13's is just too much gear for the highway in my opinion.
 
I’m running 5.13’s on my 14 with an auto trans and 37’s. I’m fine with it. I turn just under 3000 at 75 and that’s fast enough for me. Pulling some of the hills around salt lake isn’t too bad but I use manual shift mode and it works out just fine.
 
JKDream said:
This happens with 5:13's as well, or at least from my experience.
I'm actually the opposite, I have 5:13's now and if I had to do it over again I'd go 4:88's.
Mines not a daily either, but I don't trailer it to the trails. 5:13's is just too much gear for the highway in my opinion.
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Oh I’m sure it does, in reality you still have a V6 pushing those big heavy tires/wheels so nothing is going to be perfect and not push the engine. Really all depends on what you want the Jeep for mostly, mine current one sits in the garage Monday - Friday, still has 4.10s, and 35s and honestly it’s not bad by any means, but I’d like a lower gear anytime I’m off the road. Always debates on this subject so whatever works for you and your Jeep and life style will be best, think the point is you can’t go wrong either way


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I've been running 37's and 4.88 gears with an auto on my Brute for 4 years now without any issues, including towing my Xventure trailer...I currently have a PR44 up front and a PR60 in the rear...granted, I also have a 5.7 hemi...but as far as getting into the hills, I just go into auto shift mode and just select best gear for rpm in any situation...
 
benatc1 said:
Always debates on this subject so whatever works for you and your Jeep and life style will be best, think the point is you can’t go wrong either way


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Agree 100%, that was just my experience with the gearset. One benefit from it is the increased crawl gear ratio if you don't have a Rubicon like myself.
 
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