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Discussion Starter · #1 ·
So I'm getting frustrated with the 4.10 gears in the 2012 JKUR MANUAL. I have an AEV 3.5" lift, 35" Duratracs (34.5 actual), heavy bumpers, heavy Warn Powerplant winch, and a 100 pound dog (ha).

At first the gears were near perfect! But since adding all the weight it's not ideal now.

I live in Colorado and go into the mountains often and wheel easy/moderate trails. I tow frequently and all the aforementioned mods plus the frequent towing (1500-2000 lbs) has got me wanting the right gears

I'm very very likely not going any bigger then 35's because I drive a lot of miles per year 20-30K (MAYBE I would do 37's years down the road but they are completely impractical for my usage and requirements currently).

For those of you who live at altitude (5000+) AND tow frequently AND have the MANUAL transmission- can you give me feedback on 4.56 & 4.88 gears please?

Also I'd be super interested in doing a test ride in a similarly built rig thats geared 4.56/4.88 and provide refreshments for the opportunity if that's an option!

Thanks and yes I read many gear threads and didn't want to hijack threads to ask this specific question. I also have re-geared before to 4.88 on an LJ but the drivetrain and tires etc are incomparable in this situation :)
 

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Your lucky, im in colorado with 35 duratracs with 3.21 gearing, I cant accelerate past like 25 mph going up berthud pass ha it rough
 

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Just a thought, if you ever go 37's you'll be in the same boat unless you go 4.88s.
 

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Discussion Starter · #4 ·
Your lucky, im in colorado with 35 duratracs with 3.21 gearing, I cant accelerate past like 25 mph going up berthud pass ha it rough
Dang. That sounds dangerous! I feel like it bogs so much with my setup it's uncomfortable safety wise up the passes too
 

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Discussion Starter · #5 ·
Just a thought, if you ever go 37's you'll be in the same boat unless you go 4.88s.
So true. Now it seems to hinge on what I'll do in the future, but I don't think 37's are practical- cost, weight, new wheels and on and on. A guy I know said I could drive his 4.88 auto with 37's but I don't think it would give a realistic comparison :(
 

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I think you would be fine with either the 4.56 or the 4.88. The ONLY reason I (personally) would go with the 4.88 is I can get the softer steel gears that are US-made and indestructible, relatively speaking. I have an auto, but I feel your pain. Unlike what AEV says, the 35s flat-out suck here with anything less than 4.56.

In conclusion (since you tow) I would undoubtedly go with the 4.88s. The RPMS are about 200-300 higher. Have you seen the JK/JKU RPM chart yet?
 

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Slightly different (mine's an '09) but I'm running 5.13's with the manual and 37's. I can run I-25 from Cheyenne down to the Springs without having to constantly shift gears but I have to keep it right around 65 MPH to maintain any kind of mileage (about 14 MPG's). Haven't tried towing anything with it yet though.
 

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Supercharger? Yeah I know its 5grand. I'm a pilot and I know that in that region pilots prefer to fly supercharged or turbocharged engines vs naturally aspirated engines.
 

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Discussion Starter · #9 ·
I think you would be fine with either the 4.56 or the 4.88. The ONLY reason I (personally) would go with the 4.88 is I can get the softer steel gears that are US-made and indestructible, relatively speaking. I have an auto, but I feel your pain. Unlike what AEV says, the 35s flat-out suck here with anything less than 4.56.

In conclusion (since you tow) I would undoubtedly go with the 4.88s. The RPMS are about 200-300 higher. Have you seen the JK/JKU RPM chart yet?
The US made gears are attractive and add an element that I have read you post before but now weighs in heavier after having it sink in twice.

Yes I've seen the chart and its definitely helpful but if I can experience it first hand and/or get input to help being new things to light (or finally sink in) I'm into that!

The tow thing is 25-33% of all driving so I don't want to gear for that but it's frequent enough to be relatively high on the priority list
 

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Discussion Starter · #10 ·
Slightly different (mine's an '09) but I'm running 5.13's with the manual and 37's. I can run I-25 from Cheyenne down to the Springs without having to constantly shift gears but I have to keep it right around 65 MPH to maintain any kind of mileage (about 14 MPG's). Haven't tried towing anything with it yet though.
Interesting. Why 5.13's? What RPM's in 6th gear at 65 mph? Thanks
 

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Discussion Starter · #11 ·
Supercharger? Yeah I know its 5grand. I'm a pilot and I know that in that region pilots prefer to fly supercharged or turbocharged engines vs naturally aspirated engines.
That would be sweet
 

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Interesting. Why 5.13's? What RPM's in 6th gear at 65 mph? Thanks
The primary reason for the 5.13's is that I wanted that little extra bit of low range on the trail and when I finish my current job in a couple of years the Jeep will be my secondary vehicle so I won't have to worry about mileage or highway driveability with the deeper gears. As it is right now I only drive it 5 weeks out of the year anyway so the highway aspect was never a primary concern.

With the current setup I'm turning 2500 RPM's at 65. The site I use for calculations ( Gear Ratio Calculator ) shows that 4.88's would be running at 67 MPH at 2500 RPM's so it really isn't too drastic of a change at highway speed.

Also, I believe that the sweet spot for RPM's is slightly different between the 3.8 and 3.6 so the 4.56's or 4.88's might be the better bet for highway purposes.

If you want to run your own numbers on the site above, the transmission is listed as NSG370 Close Ratio and the transfer case is listed as NVG241OR.
 

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Discussion Starter · #13 ·
The primary reason for the 5.13's is that I wanted that little extra bit of low range on the trail and when I finish my current job in a couple of years the Jeep will be my secondary vehicle so I won't have to worry about mileage or highway driveability with the deeper gears. As it is right now I only drive it 5 weeks out of the year anyway so the highway aspect was never a primary concern.

With the current setup I'm turning 2500 RPM's at 65. The site I use for calculations ( Gear Ratio Calculator ) shows that 4.88's would be running at 67 MPH at 2500 RPM's so it really isn't too drastic of a change at highway speed.

Also, I believe that the sweet spot for RPM's is slightly different between the 3.8 and 3.6 so the 4.56's or 4.88's might be the better bet for highway purposes.

If you want to run your own numbers on the site above, the transmission is listed as NSG370 Close Ratio and the transfer case is listed as NVG241OR.
Cool. Thank you. Will check it out
 

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Discussion Starter · #14 ·
4.88 ordered! Thanks for the input
 
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