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Go 4.56 gears or don't use OD?

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Old 02-12-2017, 06:28 PM
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Exclamation Go 4.56 gears or don't use OD?

2016 JKURHR, AUTO, 3.73

285/75 Toyo ATs, aftermarket rear bumper and carrier, winch coming soon.

Need this thing to be super cool with the highway, like actually cruise the speed limit. Trips consists of 3000 miles. Want the ECO light on as much as possible... Its based off engine load, so when its on, MPGs improve.

Live in midwest, don't wheel here, sees lots of pavement.

Will maybe... and Im talking maybe , might go to 37s in a couple years.. no guarantee. But will for sure always be a 285 or 315 tire Jeep.

Looking to do Mopar 4.56 gears, cause from the chart, they could work both with 35s or 37s.
Right now my tire measures 33.5" on the Jeep, so 4.56s is spot on, or would even add some pep

Or just don't use OD and not worry about regear? Cause it drives great on inclines not using OD.

Not looking to gain MPG, but don't want it to go in the crapper either.


4.10s seem like a waste of time and $$
Old 02-12-2017, 07:20 PM
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IMO 4.56 gears with 35's would be minimum. I ran factory 4.10 with 315/70/17 on a 16' auto and while it was acceptable it was not ideal. I definitely would have preferred 4.56. This was on a light 2dr without a bunch of added weight. With a JKU you are around 500lb heavier than a JK plus you are more likely to have more passengers, cargo etc. The 4.88's seem like a better choice and would be a better match if you do ever decide to go larger in the future.

My fuel mileage averaged about 17mpg with 4.10's and "35's". Now with 5.38's on D60's and 40's, I lost about 3mpg. I now run just under 3000rpm @ 70mph and my eco light is on quite often.
Old 02-12-2017, 08:05 PM
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Originally Posted by up4rox
IMO 4.56 gears with 35's would be minimum. I ran factory 4.10 with 315/70/17 on a 16' auto and while it was acceptable it was not ideal. I definitely would have preferred 4.56. This was on a light 2dr without a bunch of added weight. With a JKU you are around 500lb heavier than a JK plus you are more likely to have more passengers, cargo etc. The 4.88's seem like a better choice and would be a better match if you do ever decide to go larger in the future. My fuel mileage averaged about 17mpg with 4.10's and "35's". Now with 5.38's on D60's and 40's, I lost about 3mpg. I now run just under 3000rpm @ 70mph and my eco light is on quite often.
Wow. 17 mpg??? How?!!! I'm a JKU on 35s fully equipped driving from LA to Mammoth (6 hrs of freeway) and averaged 10.3 mpg
Old 02-13-2017, 04:11 AM
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Originally Posted by Ripa777
Wow. 17 mpg??? How?!!! I'm a JKU on 35s fully equipped driving from LA to Mammoth (6 hrs of freeway) and averaged 10.3 mpg
Holy cow... 10.3!

I've never seen mpg that low... not even on trails
Lol
Old 02-13-2017, 04:58 AM
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Originally Posted by Ripa777
Wow. 17 mpg??? How?!!! I'm a JKU on 35s fully equipped driving from LA to Mammoth (6 hrs of freeway) and averaged 10.3 mpg
Are you calculating your mileage or just reading off the dash computer.
Old 02-13-2017, 05:06 AM
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Do yourself a favor and re-gear. You will thank yourself every single time you get in and drive the jeep. "not using overdrive" is not a solution....lol. It's pretty windy out my way.....and every time I'm on the interstate doing 75 in a strong headwind, I recall how I would previously have had to downshift from 4th to 3rd at times just to keep going. Now I just cruise along in 5th as I should. I had been on 37s and 4.10 gears before that, so 5th was non-existent.
Old 02-13-2017, 05:09 AM
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Originally Posted by resharp001
Do yourself a favor and re-gear. You will thank yourself every single time you get in and drive the jeep. "not using overdrive" is not a solution....lol. It's pretty windy out my way.....and every time I'm on the interstate doing 75 in a strong headwind, I recall how I would previously have had to downshift from 4th to 3rd at times just to keep going. Now I just cruise along in 5th as I should. I had been on 37s and 4.10 gears before that, so 5th was non-existent.
I'm going to... traveling from Missouri to Colorado, the winds in Kansas keeps the engine load up so high and OD can't keep it at 70-75mph

You running 4.56s?
Old 02-13-2017, 05:45 AM
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Originally Posted by Scvette01
I'm going to... traveling from Missouri to Colorado, the winds in Kansas keeps the engine load up so high and OD can't keep it at 70-75mph

You running 4.56s?
I'm running 5.13s with 3.6L engine, auto tranny, and 37" Nitto Trail Grapplers. I will admit, the 5.13s are aggressive for the 3.6L. MOST people go with 4.88s, but my jeep is just a part-time driver and I appreciate the off-road benefits of the gears.

I'd agree with your original post that 4.56 might be best for you as it they would work with 35s, and still be acceptable with 37s if you ever made that jump. Moving to 4.88s would be a bit aggressive unless you already had 37s, but just my opinion.

I drove over a year on 37s with 4.10s......by the end, I was so worn down. Wish I had regeared sooner than I did.
Old 02-13-2017, 06:27 AM
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Originally Posted by Ripa777
Wow. 17 mpg??? How?!!! I'm a JKU on 35s fully equipped driving from LA to Mammoth (6 hrs of freeway) and averaged 10.3 mpg
I'm on 35's w/4.88 and I get about 16.1mpg on the freeway. Stock bumpers, tire carrier etc.
Old 02-13-2017, 06:37 AM
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Originally Posted by resharp001
I drove over a year on 37s with 4.10s......by the end, I was so worn down. Wish I had regeared sooner than I did.
That's how I feel now.. Just worn down after driving a 600 mile, or more, stretch in a day.

Especially if battling winds.
I'm not worried about off road performance vs highway, due to the fact we only wheel in Moab and that is just once a year. If we make it that way. And 4.56 seem that they are manageable if I decide on 37s in the far future... Like that .5% chance if I do


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