5.13 Gears, My Thoughts and Real Numbers

[JTenn]

Keep in mind Im NOT coming from an "experience" point of view like I'm an expert, just relaying what I've seen over and over from these people in the biz.

Yeah no worries. I'm far from an expert myself. This has just been my experience and I'm really happy with my gearing set up. Moving from 3.73's to 5.13's was a HUGE jump and I honestly questioned it before hand but in hind sight it was the perfect move for me and my application. I would do it again without hesitation.

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[JarHeadLV]

Yeah no worries. I'm far from an expert myself. This has just been my experience and I'm really happy with my gearing set up. Moving from 3.73's to 5.13's was a HUGE jump and I honestly questioned it before hand but in hind sight it was the perfect move for me and my application. I would do it again without hesitation.

I have 37's now (37x13.5r17's) and Im going to switch to a 38x12.5r17 Nitto Trail Grappler - which are actually 4lbs lighter per tire. I have 4.10's (stock) now. I rarely drive on the highway, But I know I do need to re gear soon. Now I guess I gotta decide between 4.88's and 5.13's

 

[JarHeadLV]

One thing to consider is that you have jls and jts and they often get lumped together in terms of gearing advice. The JT is heavier, usually carries more, and tows so it benefits from deeper gears more than the jl where the pentastar is still a dog but at least adequate.

Personally 5.13s seem like a great sweet spot for anything from 37s to 39s. A little over kill for 35s but if people don't mind a few hundred extra rpm on the highway it will still do just fine. Another thing to consider is that 5.13s turn 8th in to the current 6th more or less, so if you are running 6th most of the time on the highway the 5.13s won't really be running any higher rpm at 8th but give you a whole lot more grunt.

I have a JT, I always watch stuff regarding "Mojave" JT's. I don't care about stuff for JL's. Mostly because I have a Mojave and 85% of the time stuff that fits on a JL or JT Rubicon, does not fit on a Mojave.

 

[AustinL911]

I have 37's now (37x13.5r17's) and Im going to switch to a 38x12.5r17 Nitto Trail Grappler - which are actually 4lbs lighter per tire. I have 4.10's (stock) now. I rarely drive on the highway, But I know I do need to re gear soon. Now I guess I gotta decide between 4.88's and 5.13's

Without question, go with the 5.13s. Its not just about RPM at a given speed, its also about the load on the engine. These engines love RPMs.

 

[JarHeadLV]

Without question, go with the 5.13s. Its not just about RPM at a given speed, its also about the load on the engine. These engines love RPMs.

ok, good to go.

 

[bleda2002]

I have a JT, I always watch stuff regarding "Mojave" JT's. I don't care about stuff for JL's. Mostly because I have a Mojave and 85% of the time stuff that fits on a JL or JT Rubicon, does not fit on a Mojave.

The tribal knowledge that makes them experts is coming from jls and jts. No one specializes in just regearing mojaves so they're basing it on what they have done which is probably tons of jls and a few jts.

 

[JTenn]

I have 37's now (37x13.5r17's) and Im going to switch to a 38x12.5r17 Nitto Trail Grappler - which are actually 4lbs lighter per tire. I have 4.10's (stock) now. I rarely drive on the highway, But I know I do need to re gear soon. Now I guess I gotta decide between 4.88's and 5.13's

That will look great! I have yet to hear anyone say they regret going with 5.13’s. I have however heard some say they wish they would have went 5.13’s instead of 4.88’s. 5.13’s just open up options for future growth if you ever wanted. At the end of the day you being happy with your rig is all that matters. Everyone else's opinions are exactly that. But either way you go, it's better than your current 4.10's.

 

[JarHeadLV]

The tribal knowledge that makes them experts is coming from jls and jts. No one specializes in just regearing mojaves so they're basing it on what they have done which is probably tons of jls and a few jts.

I get that, but re gearing a JT Mojave is no different than re gearing a JT Rubicon, correct? My point was I only watch/read stuff about JT's

 

[JarHeadLV]

That will look great! I have yet to hear anyone say they regret going with 5.13’s. I have however heard some say they wish they would have went 5.13’s instead of 4.88’s. 5.13’s just open up options for future growth if you ever wanted. At the end of the day you being happy with your rig is all that matters. Everyone else's opinions are exactly that. But either way you go, it's better than your current 4.10's.

ok, makes sense, BUT I gotta rely on what people with experience recommend because I have NO experience with Jeeps, gears, etc....

I've owned like 8 trucks in the last 25 years and all were 1 ton diesels. They were made to tow from the start so I didnt have to change anything. Jeeps are like AR15's, you can change EVERYTHING!!!

 

[JTenn]

ok, makes sense, BUT I gotta rely on what people with experience recommend because I have NO experience with Jeeps, gears, etc....

I've owned like 8 trucks in the last 25 years and all were 1 ton diesels. They were made to tow from the start so I didnt have to change anything. Jeeps are like AR15's, you can change EVERYTHING!!!

Agreed, they are super modular and can be made into any configuration you can dream of. Love my AR's too. All one needs is big piles of cash. Sounds like you should follow your gut and go with the 4.88’s the experts recommend. It's alot of time and money to put out there to not be sure about where it's being spent. I do drive my JT every day and wheel pretty hard on the weekends. As stated above, no regrets about my 5.13's. I will NEVER move up in tire size and think "I should have went deeper on the gearing" also, I don't have the Rubi 4:1 transfer case so the 5.13's help me there as well.

 

[MrClortho]

My plans were accelerated and I ended up with 5:13s and 37s. The Jeep feels like it has 100 more horsepower and actually gets 2-3 mpg better mileage over the 3.73s and 35's. The Glad actually stays in 8th gear on the highway unless it is a sizeable hill. I also tow a 4klbs travel trailer about two weekends a month, and a big improvement there too.

5.13s for the win, no question.

 

[JTenn]

My plans were accelerated and I ended up with 5:13s and 37s. The Jeep feels like it has 100 more horsepower and actually gets 2-3 mpg better mileage over the 3.73s and 35's. The Glad actually stays in 8th gear on the highway unless it is a sizeable hill. I also tow a 4klbs travel trailer about two weekends a month, and a big improvement there too.

5.13s for the win, no question.

Yup, me too. The general consensus says 5.13's hands down. At least on this forum anyway. And that's for real world every day driving. Everyone has they're own opinion and that's cool too.

 

[Wheelin98TJ]

I have 37's now (37x13.5r17's) and Im going to switch to a 38x12.5r17 Nitto Trail Grappler - which are actually 4lbs lighter per tire. I have 4.10's (stock) now. I rarely drive on the highway, But I know I do need to re gear soon. Now I guess I gotta decide between 4.88's and 5.13's

With 4.88 and 38" tires that I'll assume are about 37" tall, you'll turn about 2,100 RPM at 70 MPH. That's not really enough RPM for the 3.6L to comfortably cruise with 38" tires.

You want at least 5.13 or 5.38. 5.13 will be about 2,200 RPM at 70, 5.38 will be about 2,300 RPM. I'd go with 5.38.

 

[JarHeadLV]

With 4.88 and 38" tires that I'll assume are about 37" tall, you'll turn about 2,100 RPM at 70 MPH. That's not really enough RPM for the 3.6L to comfortably cruise with 38" tires.

You want at least 5.13 or 5.38. 5.13 will be about 2,200 RPM at 70, 5.38 will be about 2,300 RPM. I'd go with 5.38.

Im going to guess the 38"s are actually close to 36" (if that matters) based on my 37's are exactly 35" when mounted on my truck, same with a buddys truck with 37's.

I wonder when I DO move up to new gears, what can I sell my current 4.10s for? they have 3,100 miles on them currently

 

[JTenn]

With 4.88 and 38" tires that I'll assume are about 37" tall, you'll turn about 2,100 RPM at 70 MPH. That's not really enough RPM for the 3.6L to comfortably cruise with 38" tires.

You want at least 5.13 or 5.38. 5.13 will be about 2,200 RPM at 70, 5.38 will be about 2,300 RPM. I'd go with 5.38.

That's assuming it will naturally find 8th gear. Will most likely spend more time in 6th and 7th.

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