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[Save The Manuals!]

Iowa is not flat. As a native Iowegian who pedaled a bicycle across the state numerous times, I can tell you that for a fact. I drove my new 2024 JLU Sport S MT from Missouri to Iowa last weekend. When I crossed the border and encountered Southern Iowa's hills with the cruise set at 78mph, it quickly fell to 72mph or so before I crested the hill and then it went back up to 78mph. I kinda had to laugh; sure, it's shaped like a brick, what do you expect?? But my 6-speed diesel pickup isn't exactly an aerodynamic fiberglass bullet, and it doesn't do that. However, it has a turbo (Cummins 5.9 liter turbo diesel). Is that the issue here? Is there any way to improve the performance on the interstate?

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[Gregj]

Gears is the answer.

Gregj

 

[Save The Manuals!]

Gears is the answer.

Gregj

What do you recommend? Not that it would happen until I'm out of warranty..

 

[Gregj]

I have BFG K02’s in 37’s and swapped to 5:13’s. I was torn between 4:88’s and 5:13’s. If I did it again I would go with 5:38’s. It drives really good with this combo, 70 mph is about 2500 rpm and it doesn’t loose a lot of speed on hills now. My son has 35’s and 4:88’s and I think they feel about the same.

Gregj

 

[Gregj]

Both of our Jeeps were Sports and the stock gearing was horrific, you can order a Jeep with 4:88’s and 33’s so depending on what size tire you want to run you really can’t go wrong with a LOT more gear.

Gregj

 

[OminousSkitter]

Yeah, all the 6 speeds were undergeared from the factory. Sports/Saharas should have been 4.10, rubicons 4.56, etc. just saying the minimum gearing to actually use all 6 gears.

 

[AVGeek99]

Iowa is not flat. As a native Iowegian who pedaled a bicycle across the state numerous times, I can tell you that for a fact. I drove my new 2024 JLU Sport S MT from Missouri to Iowa last weekend. When I crossed the border and encountered Southern Iowa's hills with the cruise set at 78mph, it quickly fell to 72mph or so before I crested the hill and then it went back up to 78mph. I kinda had to laugh; sure, it's shaped like a brick, what do you expect?? But my 6-speed diesel pickup isn't exactly an aerodynamic fiberglass bullet, and it doesn't do that. However, it has a turbo (Cummins 5.9 liter turbo diesel). Is that the issue here? Is there any way to improve the performance on the interstate?

You can't compare a 3.6L Pentastar to a Cummins deisel, or any other deisel for that matter, at least not one in a truck. Deisels have way more torque.

Regearing would lessen (maybe solve) your problem, but that's a very expensive fix to prevent loosing 6mph on a hill. The gearing in Wranglers isn't optimal, but with stock tire sizes it get's the job done most of the time, unless you live out West constantly driving over mountain passes.

Are your tires larger than stock? I'm guessing no, because if you were you'd likely loose a lot more than 6mph on a long hill.

The cheaper (although a PITA) would simply be to downshift on hills like this. That is how an automatic is able to maintain speed on those hills.

And spoiler alert, even if you regear, you're still going to loose speed on bigger hills. I run 37s with 4.88 gears. I think this combination is optimal for the midwest (I live in MN). I can maintain speed on most hills in 6th gear. But in the mountains out west I'm downshifting on the mountain passes; as low as 4th gear on interstate passes, 3rd on a lot of non-interstate passes, and that's just to maintain about 45mph.

 

[bd100]

Keep it in 5th for a while? Better than lugging up the hills in 6th, and no big difference in MPG on the downhill.

 

[YBABRAT]

IMO the ZF auto is the only choice along with better axle ratio. A 4.10 is minimum for Sport and Sahara. 4.88 is a good all around choice with up to 35s.

 

[Ratbert]

Sorry, but the 6 speed manual in these things is geared horribly tall.

 

[Aturking]

Its your gears. I did the drive across Iowa with my JLU willys 6speed with stock gears and 33's towing my enclosed trailer (camper conversion). I couldn't pull any grade in 5/6th and ended up having to shift in 3rd several times to pull the hills.

Made the trip a year later with 4.56 and 35's, never left 6th at 75. Puts the engine up in the power. If I had to do it again I would probably go 4.88. I do some towing and its still a little underpowered towing with the 35's. One thing I hate about the JL 3.6 compared to my JK is that it almost acts like it has turbo lag under 2250 RPM.

So long story,

Get gears and screw the warranty. Mine went in at 8500 miles..

 

[Twisted10]

392 is your answer...

or cummins swap

 

[TheRaven]

Iowa is not flat. As a native Iowegian who pedaled a bicycle across the state numerous times, I can tell you that for a fact. I drove my new 2024 JLU Sport S MT from Missouri to Iowa last weekend. When I crossed the border and encountered Southern Iowa's hills with the cruise set at 78mph, it quickly fell to 72mph or so before I crested the hill and then it went back up to 78mph. I kinda had to laugh; sure, it's shaped like a brick, what do you expect?? But my 6-speed diesel pickup isn't exactly an aerodynamic fiberglass bullet, and it doesn't do that. However, it has a turbo (Cummins 5.9 liter turbo diesel). Is that the issue here? Is there any way to improve the performance on the interstate?

Yeah, downshift. The Wrangler (with its usual engines) isn't exactly packed with power, it needs gears...and with said gears, it gets by pretty well. But it's not going to compare to a pickup...let alone a diesel.

 

[John VonJeep]

When I’m buying a car, my transmission preferences are as follows:

Excellent manual <— no Jeeps are here
Average manual <— my old JK’s 6-speed
Excellent automatic <— Jeep 8-speed
Shitty manual <— JL 6-speed
Average automatic
Shitty automatic

Unfortunately, it is what it is with the JL.

 

[VKSheridan]

It’s a Jeep, not a Hellcat dear….

Your gearing is matched to your engine’s torque which is matched to its emissions rating which is matched to the octane it burns which is matched to its ethanol fuel rating and Iowa is certainly known to sell ethanol.

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