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Discussion Starter #1
New Jeep owner. Just purchased a 2014 Wrangler unlimited. It now has a 3.5" suspension lift and 35s on it.

It has 3.73 gears in it. It is a daily driver, weekend trail rider. Are the 3.37s sufficient or should I consider upgrading? I know the general rule of thumb is the steeper the gear, the worst the gas mileage. However, in my experience in other vehicles, when you reach a point of a certain size/weight tire, upgrading the gears has no adverse effect or even slightly improves mileage. Is that the case with Jeeps also?
 

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I can only speak from my experience, but regearing definitely changed things for me for the better.

I have a 2013 JKU that came with 3.73's. At first I had 33's and the TF 1.5" leveling kit, and the ride was perfect. Then I upgraded to 35's and the TF 2.5" coil lift, and I noticed definite power loss. It wasn't debilitating, but where I actually noticed it the most was on my 5-hour highway drives that I take every other weekend. Any incline whatsoever, and the needle would immediately drop. Cruising at 70 would suddenly drop to 60 (and the folks behind me weren't too pleased :p). And I'm not talking steep mountain climbs, either; more like bunny hills. I was afraid to use cruise control after the first couple of inclines. :rofl:

A few months ago (Sept), I regeared to 4.56's and I have to say it's probably the best "mod" money spent so far. No more power loss, and I can't say that my gas mileage changed. Can't really give you real numbers because I never check my MPG (i.e., Jeep); all I know is my gas station trips haven't become more frequent enough to notice.
 

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I can only speak from my experience, but regearing definitely changed things for me for the better. I have a 2013 JKU that came with 3.73's. At first I had 33's and the TF 1.5" leveling kit, and the ride was perfect. Then I upgraded to 35's and the TF 2.5" coil lift, and I noticed definite power loss. It wasn't debilitating, but where I actually noticed it the most was on my 5-hour highway drives that I take every other weekend. Any incline whatsoever, and the needle would immediately drop. Cruising at 70 would suddenly drop to 60 (and the folks behind me weren't too pleased :rofl:). A few months ago (Sept), I regeared to 4.56's and I have to say it's probably the best "mod" money spent so far. No more power loss, and my gas mileage didn't really change *too* much, I don't think. Can't really give you real numbers because I never check my MPG (i.e., Jeep); all I know is my gas station trips haven't become more frequent that I notice.
I took the same mod path as you except I had 3:21 gears. Were fine with 33s but sucked with 35s. Am happy now with 4:56

In 4 LO I can crawl up rocks and hardly need to touch the skinny petal.
 

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I have 4.56 with my 35's and I wouldn't have it any other way. The 3.21 gears were horrible even with stock tires. 6th gear was basically useless. I upgraded the gears a week before I put the tires on. I now have no problem holding my freeway speed up the small hills we have here in fly-over country.

One thought, if you can make it work out, though.

If you have anyone in your area that has a Jeep with 3.21 gears, you may look to see if you can swap axles with them. They may like 3.73 gears but don't want to pay for a regear. I'm sure you could find someone who would pay you a little to do that swap.

As long as you're stepping away from gears, why not do it to an axle with throw-away gears anyway? That may be more complicated than you want to deal with but if you can make it work out you'll maybe be able to offset the cost a little.
 

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i've heard that a lot of folks with the new 3.6L engine are very happy with the 4.56 gears. with 35s, you shouldn't suffer on the highway with a 4.56 like you're probably doing with the 3.73 ratio; and it'll give you a bit of extra krawling umph on the trail...

less skinny pedal always equates to a better wheeling experience in my opinion.
 

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yeah definitely good with the 4.56; i am running 4.88s in the 3.8L auto with 37" tires. drove from tampa, fl to fayetteville, nc and averaged about 16.2 mpg ~ 2000 - 2200 rpm most of the way.

you just have to be concious of rpm. try not to lug the engine or drive at 2500-3000 rpm either. or your gas mileage will suffer.
 

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Discussion Starter #10
Thanks. I had a truck with 23" wheels, 315/40 tires on it (street truck.) I had 3.73 gears in it...and it just was a dog. Slapped in 4.56s and it was GREAT...and mileage improved. I figured it would be the same scenario with a Jeep. Right now...its ok, but I know it can be better. I would rarely do any highway driving in this....unless its to a trail event.
 

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Thanks. I had a truck with 23" wheels, 315/40 tires on it (street truck.) I had 3.73 gears in it...and it just was a dog. Slapped in 4.56s and it was GREAT...and mileage improved. I figured it would be the same scenario with a Jeep. Right now...its ok, but I know it can be better. I would rarely do any highway driving in this....unless its to a trail event.
Yep. Gearing needs to be matched to the tires for the best performance (acceleration and mileage). It's all about keeping the engine in the RPM range that makes it perform the best.

Taller gears drop RPMs. That makes for better mileage. But if you drop RPMs too far, the engine won't be making any power and it ends up having to work harder, killing your mileage (and making it a dog to boot).

Adding bigger tires is like swapping in taller gears. In order to get back to factory performance you have to put in shorter gears to match the taller tires.
 
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