Concerns with 488’s and 37’s.

13_gecko_rubi

13_gecko_rubi

Caught the Bug
Having had 4.88s and 37s, which I did because it was a daily driver and I thought would be better on fuel, I tell everyone to do 5.13s. Mine dropped into 4th if I sneezed and into 3rd on any kind of hill. 5.13s would help to hold higher gears longer. 5.13s in 5th gets better fuel economy than 4.88s in 4th.

I unless you have a 5.7, then I'd say 4.56 :)

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pop2tu

pop2tu

Active Member
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. 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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Thanks for the reply. I have a 13 JKU with Rubicon Dana 44s and 37s. This is my problem, I drive 70 miles each way to work. I have 2 hills that raise up about 1000- 1200 feet, total elevation over 4000ft. With 4:10s I can run 55-60, as long as I watch temp gauge, any faster it gets hot and goes into limp mode. Of course everyone is passing me doing 75-85. I talked to a friend running a 10 JKU with 5.13s and 35s he has the same issues on one of the hills


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monstrousmac

monstrousmac

Caught the Bug
Brute said:
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...
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Soon to be mine. I can’t wait to get them under my Jeep. Dynatrac needs to hurry and finish building yours, hahaha!
 
fiend

fiend

Caught the Bug
The 3.8 is not comparable to the 3.6. Not only are the engines different, but the transmissions are different.

For the 3.8 and auto with 37s, 5.38 is the best, but for the fact that the pinion is tiny and weak. So unless you have 60s, you’re stuck with 5.13s. It’s fine on the trail, but suffers on the highway.

For the 3.6, I have the impression that 4.88s and 5.13s are suitable.
 
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jesse3638

jesse3638

Hooked
pop2tu said:
Thanks for the reply. I have a 13 JKU with Rubicon Dana 44s and 37s. This is my problem, I drive 70 miles each way to work. I have 2 hills that raise up about 1000- 1200 feet, total elevation over 4000ft. With 4:10s I can run 55-60, as long as I watch temp gauge, any faster it gets hot and goes into limp mode. Of course everyone is passing me doing 75-85. I talked to a friend running a 10 JKU with 5.13s and 35s he has the same issues on one of the hills


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2 different motors, 2 different transmissions (if running auto).
OverlanderJK said:
I would do minimum of 5.13’s. I would rather have the power than the gas mileage though.


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I'm planning on going this route as well if I ever can get my 37's..haha.

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BaddestCross

BaddestCross

Active Member
fiend said:
The 3.8 is not comparable to the 3.6. Not only are the engines different, but the transmissions are different.

For the 3.8 and auto with 37s, 5.38 is the best, but for the fact that the pinion is tiny and weak. So unless you have 60s, you’re stuck with 5.13s. It’s fine on the trail, but suffers on the highway.

For the 3.6, I have the impression that 4.88s and 5.13s are suitable.
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A bit of a sidetrack, but I've been meaning to ask you about your Rubicrawler... Do you find yourself using 2LO much and if so, under what circumstances?

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407
 
BaddestCross

BaddestCross

Active Member
fiend said:
I use the 2.7:1 a lot. The 4:1 is often times too low.

I have used the 10.8:1 once. [emoji23]
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Lol. I bet the low low is way low. 🤣

Just wondering if the 2LO would be good for going up the mountain roads (like the 18 up to Big Bear) when they get really steep. I'm sure it's good in 4WD for cruising between obstacles since now my 4LO is too low for most situations unless really crawling.

If I'm in 4LO now, I'm usually in 2nd gear or D most of the times in-between obstacles and even that gets annoying at times.

--
Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407
 
fiend

fiend

Caught the Bug
BaddestCross said:
Lol. I bet the low low is way low. 🤣

Just wondering if the 2LO would be good for going up the mountain roads (like the 18 up to Big Bear) when they get really steep. I'm sure it's good in 4WD for cruising between obstacles since now my 4LO is too low for most situations unless really crawling.

If I'm in 4LO now, I'm usually in 2nd gear or D most of the times in-between obstacles and even that gets annoying at times.

--
Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407
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I have never used the 2.7:1 on the highway or paved roads. I think that’d be too low.
 
N

NeverLost00

New member
For what it’s worth I’d try a programmer before you make any decisions.
I’m loving my superchips flashpaq. I’m running a ‘14 rubicon unlimited, 6 speed, 4:10, and 37 ridge grapplers. I’ve had it out only a few times since I installed the tires. In 12,000 miles I’ve never thought I needed to regear. Though I live very close to sea level.
IMO 4:1 TC is a must.
 
TheGrendel

TheGrendel

Active Member
NeverLost00 said:
For what it’s worth I’d try a programmer before you make any decisions.
I’m loving my superchips flashpaq. I’m running a ‘14 rubicon unlimited, 6 speed, 4:10, and 37 ridge grapplers. I’ve had it out only a few times since I installed the tires. In 12,000 miles I’ve never thought I needed to regear. Though I live very close to sea level.
IMO 4:1 TC is a must.
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:Disappointed: dear lord.
 
WJCO

WJCO

Meme King
NeverLost00 said:
For what it’s worth I’d try a programmer before you make any decisions.
I’m loving my superchips flashpaq. I’m running a ‘14 rubicon unlimited, 6 speed, 4:10, and 37 ridge grapplers. I’ve had it out only a few times since I installed the tires. In 12,000 miles I’ve never thought I needed to regear. Though I live very close to sea level.
IMO 4:1 TC is a must.
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Downhill to work both ways huh?
 
Ddays

Ddays

Hooked
NeverLost00 said:
I’ve had it out only a few times since I installed the tires...............In 12,000 miles I’ve never thought I needed to regear.
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I had to separate those two statements. A few times=12k? Must have been a couple long-ass trips! :thinking:
 
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