Gear selection help

0311DoC

New member
I have a 2016 JKUR manual transmission. I Have 4 inch EVO lift with 37” Nitto Ridge Grapplers. I’m torn with ring and pinion selection. Please educate me. People I have asked cannot give me a solid answer. 4.88 or 5.13 or 5.38 it’s my understanding that the 4.88 is better on fuel economy and the 5. Are better for power.


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If you're running the factory D44 axles I would stay away from the 5.38 and to a degree even the 5.13's for the simple fact that in the D44 housing that ring gets awfully thin once you start going lower than 5.13. That being said, if you know this going in, aren't putting big power to them and are conservative in your use of the skinny pedal you should be fine.
 

0311DoC

New member
Yes I’m still factory D44 at this time. Weekend warrior off-roader with maybe 2 times a year (Long trip) Moab, Ouray etc. running 4.10 now and have no power as you would suspect.


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FallonJeeper

New member
I went with 4.88 and 37" Falken tires on a 2016 Rubicon with D44s.

My J10 has 4.10 and 35" Km2s with D44 front and AMC 20 rear. Seems to be a compromise between daily driver mileage and of road performance.

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WJCO

Meme King
Seems like 5.13s are the general consensus from members experiences here. Also helps when your jeep is loaded up with people, tools, and gear. You will usually hear people say they had gone with one more step up, but you rarely hear people saying they had gone down for more fuel economy.
 

Samuelh3

Caught the Bug
I’m running 4.88 with 37 Nitto Trail Grapplers. It’s my daily driver and I do small trails about once a week and hard rock crawling about once a month. No complaints. Gets an average of 13 MPG and feels great off the line and on the obstacles. Only complaint is trying to go 75 mph uphill but hell its a Jeep with armor!


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0311DoC

New member
That uphill thing was a concern as well. I usually tow a trailer on a big trip. Definitely want more power. We all know Jeep’s aren’t meant for the fuel economy.


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J

JKDream

Guest
I have a 2016 JKUR manual transmission. I Have 4 inch EVO lift with 37” Nitto Ridge Grapplers. I’m torn with ring and pinion selection. Please educate me. People I have asked cannot give me a solid answer. 4.88 or 5.13 or 5.38 it’s my understanding that the 4.88 is better on fuel economy and the 5. Are better for power.


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It's preference. Do you want more low end power or better highway driving?
I have 5:13s in an auto, had I do it over again I would go 4:88 as I start to rev out at highway speeds.
Don't do 5:38s.
 

Jkzinger

Caught the Bug
It's preference. Do you want more low end power or better highway driving?
I have 5:13s in an auto, had I do it over again I would go 4:88 as I start to rev out at highway speeds.
Don't do 5:38s.

That’s for sure. A buddy of mine got talked into 5.38s by his favorite shop and as much as I told him 4.88s were just perfect for most guys with a 3.6 motor he didn’t listen. Now he runs really high rpms and drives slow to solve the issue.


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MSJKU11

Caught the Bug
That’s for sure. A buddy of mine got talked into 5.38s by his favorite shop and as much as I told him 4.88s were just perfect for most guys with a 3.6 motor he didn’t listen. Now he runs really high rpms and drives slow to solve the issue.


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I was set on 5.13 but the shop I took it to wouldn't warranty the work unless I went 4.88 because he knew I wouldn't enjoy it lol. Glad he talked me out of it and very happy with 4.88.

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notnalc68

That dude from Mississippi
Opinions will be all over the place, but I run 4.88 with 35’s, 3.6L automatic transmission. My shop recommended 4.88 for 35’s, saying he’d never had anyone wish they had gone down, but lots of people wishing they’d gone up in ratio. I run about 2950 rpms at 70. I lost about 1 mpg over the stock 4.10. I drove it from Mississippi to California, like that. No problems.

I’d go 5.13 with 37’s, but then that’s just my opinion.


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NevadaZielmeister

Caught the Bug
All this take about "more power" and "better gas mileage" are REALLY funny. You can't gear your way into better performance. The simple laws of physics apply to fuel efficiency: weight of the vehicle, aerodynamics, etc. You are fooling yourselves by saying that you will be better off for those subjects with simple gearing choice. The reason my rig does not go uphill very well on the freeway is because it weighs something like 5,500 pounds and only have 285 horsepower to the crank. So really, when you are talking gearing, think more about how it affects the performance OFF ROADING.

I went with 5.38 on 37's because I can crawl over just about anything. I know that having 4.88, 5.13 or 5.38 will not matter while on the road, only when I use my transfer case and am staring at some huge climb or some big obstacle. I would recommend understanding crawl ratio and figuring out which feels best for you while driving a friend's rig. I was really surprised how it felt to me when I hopped into another rig and tried their 4.88 ratio, ensuring that everything else was equal (4-1 transfer case, auto transmission, etc.). There are a lot of crawl ratio formulas online and can really help you understand what you want. Then get out and drive, because changing gearing can be pretty expensive, best to get it done right the first time.
 

QuicksilverJK

Caught the Bug
All this take about "more power" and "better gas mileage" are REALLY funny. You can't gear your way into better performance. The simple laws of physics apply to fuel efficiency: weight of the vehicle, aerodynamics, etc. You are fooling yourselves by saying that you will be better off for those subjects with simple gearing choice. The reason my rig does not go uphill very well on the freeway is because it weighs something like 5,500 pounds and only have 285 horsepower to the crank. So really, when you are talking gearing, think more about how it affects the performance OFF ROADING.

I went with 5.38 on 37's because I can crawl over just about anything. I know that having 4.88, 5.13 or 5.38 will not matter while on the road, only when I use my transfer case and am staring at some huge climb or some big obstacle. I would recommend understanding crawl ratio and figuring out which feels best for you while driving a friend's rig. I was really surprised how it felt to me when I hopped into another rig and tried their 4.88 ratio, ensuring that everything else was equal (4-1 transfer case, auto transmission, etc.). There are a lot of crawl ratio formulas online and can really help you understand what you want. Then get out and drive, because changing gearing can be pretty expensive, best to get it done right the first time.

When referring to more power (torque applied to tires) gearing absolutely makes a difference. Doesn't matter what your transfer case is doing. When your engine has to work harder to move a load then you will lose performance.


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NevadaZielmeister

Caught the Bug
When referring to more power (torque applied to tires) gearing absolutely makes a difference. Doesn't matter what your transfer case is doing. When your engine has to work harder to move a load then you will lose performance.

Oh sure, gearing can help with getting a better power band to the wheels based on the given situation, but you are not going to get better gas mileage or more horsepower due to regearing. That was my point. And of course, we don't need to talk about the difference between a 2.72-1 transfer case versus the 4-1 transfer case, do we? It all affects the crawl ratio, right? So how can you say that gearing doesn't make a difference and then say that the transfer box doesn't matter?

When I regeared my rig, my on-road performance went down but my off-road performance went up. Seems re-gearing is really to readjust your Jeep for a different speed range, right? That is pretty much all it does. Turning your rig from something suitable for on-road to something suitable for off-road.
 

QuicksilverJK

Caught the Bug
Your mistaken. It doesn't affect engine horsepower, but how affective that power is translated to movement. All things equal gearing will do one of two things
A- increase torque, easing the load on the engine at any given speed
B- decrease torque, making engine work harder to achieve given speed, but allowing I higher speed/ RPM ratio.
To make things easy on you think of a mountain bike. The higher the gear ratio the easier you can pedal up a hill, you will in turn have to pedal more times to get there. Vs exerting more force less times to accomplish the same thing. In a lower ratio you can go far, fast on a flat where as a high ratio your legs have to pedal faster, wasting more energy to achieve the same goal. This is where fuel mileage comes into play. Depending on driving habits, type of terrain, better fuel mileage will be achieved with lower gear ratio on flat land. On the other hand higher ratio will net better mileage climbing hills, constant speed changes, stop and go etc.


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notnalc68

That dude from Mississippi
All this take about "more power" and "better gas mileage" are REALLY funny. You can't gear your way into better performance. The simple laws of physics apply to fuel efficiency: weight of the vehicle, aerodynamics, etc. You are fooling yourselves by saying that you will be better off for those subjects with simple gearing choice. The reason my rig does not go uphill very well on the freeway is because it weighs something like 5,500 pounds and only have 285 horsepower to the crank. So really, when you are talking gearing, think more about how it affects the performance OFF ROADING.

I went with 5.38 on 37's because I can crawl over just about anything. I know that having 4.88, 5.13 or 5.38 will not matter while on the road, only when I use my transfer case and am staring at some huge climb or some big obstacle. I would recommend understanding crawl ratio and figuring out which feels best for you while driving a friend's rig. I was really surprised how it felt to me when I hopped into another rig and tried their 4.88 ratio, ensuring that everything else was equal (4-1 transfer case, auto transmission, etc.). There are a lot of crawl ratio formulas online and can really help you understand what you want. Then get out and drive, because changing gearing can be pretty expensive, best to get it done right the first time.

Are we splitting hairs, here? I must have missed the post that mentioned better gas mileage, and, “more,” power.

The OP said, “I understand 4.88 is better on fuel economy, and the 5.13 & 5.38 are better for power.” I took that to mean versus each other, not a stock gear ratio. I even mentioned that I lost about 1 mile per gallon.

As far as power, no, horsepower will not change, but the effectiveness of the horsepower will.


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Last edited:

0311DoC

New member
You guys are awesome. Thank you. Going up hill without towing now is a chore as I’m still 4.10 stock. My last trip I towed a trailer and it really sucked going up any incline and keeping up with the pack. Gas mileage we all know is never going to be ideal. Just wanted a lil extra ummf in the power band.


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TheGrendel

Active Member
i'm interested in this thread. I have a manual as well. so, i slapped on my 35s (true size just over 33 ;)) about a week ago. this passed weekend i had it loaded up for a hunting trip. large cooler. way too much crap, etc.

i was having hell getting through the Texas hill country at speed. so, now i'm thinking i'm going to need gears sooner than later. i'm about 75% sure i'll bump up to 37's when these tires wear out and I prefer not to change gears twice.

thinking 5.13. what say you wayalife?
 

notnalc68

That dude from Mississippi
You guys are awesome. Thank you. Going up hill without towing now is a chore as I’m still 4.10 stock. My last trip I towed a trailer and it really sucked going up any incline and keeping up with the pack. Gas mileage we all know is never going to be ideal. Just wanted a lil extra ummf in the power band.


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I’m geared strong, as stated earlier. I towed a travel trailer, from MS to CA. You’ll want at least 5.13.


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