My review of 5.13 gears with 33's and 42RLE

[NKlekas]

When I wanted to re-gear with the 42RLE I was shocked at how low people told me to go. @Chris & @Jerry Bransford both claimed it would be the best set up with 33's and "OK" if I wanted to go to 35's in the future. (I am about 50/50 on going to 35's). I chose to listen to these guys and I'm very happy.

I've had 5.13's on my LJ for over a month and the gears have been paired with 33's for about 95% of that time. The previous owner had 32x10.5x16R on before me and the stock gears did very "OK" with that. I daily drive my Jeep and have taken it on a camping trip up to the Triny Mountains in Idaho, a round trip of about 450 Miles. So with daily driving and the trip, I have over 1,000 on the gears and figured id do a review to help people out given the 42RLE is a typical transmission in the later model TJ's.

I'll review aspects of the gears individually and driving experiences:

Daily Driving: My jeep is much more peppy and efficient. I never drove my LJ (Or any TJ) completely stock but it drives much better. Shifts smoother has better MPG and overall seems to like the gears more. It's just more pleasant to drive. The thing that sticks out the most is the fact that at a complete stop and in Drive I have to have my foot on the break because it will crawl on its own. It never did that with the old set up and I'm shocked at the amount of Tourqe I got back from the gears. I know this explanation isn't super detailed but I can't quite explain it...My jeep just drives better, that's all there is to it.

MPG: I'm not that surprised my MPG shot up. Unfortunately, I have a Roof Rack and my RTT on for pretty much the rest of the summer. However, I was able to get one full tank of gas tracked before the rack and tent went on...I track my fuel and with my old set up I averaged about 9.4 MPG (Since I bought it in December) daily driving. I should mention I have a hardtop and since I've owned the Jeep The heater has run about 80% of that time. Anyway, the one tank I tracked with the new gears came out to 14.7 MPG around town, an increase of over 5 Miles per gallon...I honestly think I could have gotten more if I had more tanks to track. I won't say much about my trips MPG because as you can see in the picture...I was pretty loaded down with gear and the wind was brutal on the way home. I averaged about 12.8 MPG with all the gear and my wife. I never took a camping trip like this with the old gears but the trips I did take it on...with no gear, rack, and wife ... it got about the same..slightly worse actually at about 12.2 MPG...So it's still impressive.

RPMs: Yes the RPMs run higher and that's the point. I won't say that much about my daily driving RPMs because where I live... I stay below 40 MPH 70% of the time and below 55 MPH 95% of the time. I rarely pay THAT close attention to them when I drive around town because I don't need to.
However, that's usually not why we re-gear our Jeeps...I posted two pictures from my trip below to give you an example of the RPMs. With all my gear and Jeep being even MORE top-heavy with the RTT I rarely go any faster than about 70-73 MPH. Even without the gear I never go fast than about 75-78 MPH. The first picture is what the RPMs look like at about 72 MPH in 4th (O/D) the second is when it downshifted into 3rd while still going 70. I LOVE the 2700-2800 range it sits at in 4th. Keeping the RPMs high has made it much more efficient and less mind-numbing shifting every 30 seconds.

The O/D Ratio & Shifting: Now, the re-gear doesn't fix the brutal O/D problem the 42RLE has. But, like stated above, it makes it MUCH more tolerable. The gears keep the RPMs higher and it helps with the shifting, performance, and fuel efficiency. I can attest to this pretty honestly given where I live. Nevada is America's most mountainous state and where I live in Elko (NE corner of the state) we sit at about 5,500 feet elevation. (Another reason why I was so picky with my gears). The 5.13s make driving through the hills and passes much more manageable and my jeep doesn't bog down nearly as much when the road gets steep or elevation shoots up. I feel like I have more "get-up" to tung me up the mountain.

Overall: I'm extremely happy I went with 5.13s given how I use my Jeep and where I live. Like Jerry and Chris have said time and time again on here, with the 42RLE and the nature of the 4.0 engine the deeper the gears the better. if you're thinking 5.13 is too much, don't, it's great and I 100% recommend it.

Hope this helps!!

 

[Jamison C]

Thanks for the review. @DaveC and I are both planning 33s with 5.13s and the 42rle. I was considering going 5.38s, but I think the driveshaft speeds would be way too high to properly balance and be vib free.

That said, do you have any noticeable vibrations? This combo seems touchier with the Rubicon models but yours being an unlimited probably helps a lot.

 

[Vinman]

One other benefit is the transmission temps. On my auto 03 Rubicon when I switched to 5.13’s the tranny temp dropped about 15 degrees overall.

I should also note that the best fuel economy I ever got with that Jeep was when I had the 5.13’s and running 35” KO’s on lightweight aluminum rims. Mileage was better than stock when it was new.

 

[NKlekas]

One other benefit is the transmission temps. On my auto 03 Rubicon when I switched to 5.13’s the tranny temp dropped about 15 degrees overall.

I should also note that the best fuel economy I ever got with that Jeep was when I had the 5.13’s and running 35” KO’s on lightweight aluminum rims. Mileage was better than stock when it was new.

I haven’t noticed that much of a difference in tranny temps that’s why I didn’t mention it. The set up before this wasn't so bad that it was causing super high tranny temps. So it’s not something I have looked for tbh

 

[NKlekas]

Thanks for the review. @DaveC and I are both planning 33s with 5.13s and the 42rle. I was considering going 5.38s, but I think the driveshaft speeds would be way too high to properly balance and be vib free.

That said, do you have any noticeable vibrations? This combo seems touchier with the Rubicon models but yours being an unlimited probably helps a lot.

Funny you mention that. I also almost mentioned this as well…Upon re-gear the shop noticed issues with my Transfer Case and ended up completely rebuilding it and then putting a SYE kit on and a completely rebuilt the rear driveline. So to answer you question, no. But again. I just had a lot of that stuff completely rebuilt this past month

 

[HornedToad]

Thanks for sharing. I just made this same switch and love it (5.13’s with 33s and a 42rle). I have had mine up to 75 with no vibes although I have a 231 with a sssye which helps.

 

[roverhi]

What make and size of 33" ties are you running?? The Mfg and size make a difference in diameter that can be significant. A sampling of 33x10.5x15 MT tires very in Diameter from 32.5" to 33", width from 10.5" to 11.2" and weight from 53# to 64#. Those are enough differences to significantly effect mileage and speedometer/odometer readings.

I'm going with a relatively skinny 32.1" tire and debating between 4.88 and 5.13 gears. I'll never go larger than 32.5" or wider than 10.5". More concerned with rpm on a downshift to 3rd gear in the 42RLE and fuel mileage with CA gas knocking on $7.00 a gallon and probably going higher. I know don't complain about mileage on an LJ but would like to get at least shouting distance near the EPA sticker figures.

 

[NKlekas]

What make and size of 33" ties are you running?? The Mfg and size make a difference in diameter that can be significant. A sampling of 33x10.5x15 MT tires very in Diameter from 32.5" to 33", width from 10.5" to 11.2" and weight from 53# to 64#. Those are enough differences to significantly effect mileage and speedometer/odometer readings.

I'm going with a relatively skinny 32.1" tire and debating between 4.88 and 5.13 gears. I'll never go larger than 32.5" or wider than 10.5". More concerned with rpm on a downshift to 3rd gear in the 42RLE and fuel mileage with CA gas knocking on $7.00 a gallon and probably going higher. I know don't complain about mileage on an LJ but would like to get at least shouting distance near the EPA sticker figures.

They are the Patagonia M/T 33x12.5x15
Definitely a pretty beefy tire. I wanted to run A/T but I couldn't find a good set of them in stock and for a reasonable price ANYWHERE. So when I get a set of those on I bet that will effect it as well

 

[MikekiM]

How does this translate over to a 5 speed manual? Regear is on my ToDo list in the near future. No idea what gears to go with.

I run 33x12.5 on a 15x10 ProComp 69 on my 4.0 daily driver.

My primary motivation is to get 5th gear back and hopefully improve mpg. I average about 12-13 and do about 50/50 highway and local roads.

 

[NKlekas]

How does this translate over to a 5 speed manual? Regear is on my ToDo list in the near future. No idea what gears to go with.

I run 33x12.5 on a 15x10 ProComp 69 on my 4.0 daily driver.

My primary motivation is to get 5th gear back and hopefully improve mpg. I average about 12-13 and do about 50/50 highway and local roa

I'm not sure. I know Manuals do better with bigger tires so yours would be different than my 42RLE.

 

[Jerry Bransford]

How does this translate over to a 5 speed manual? Regear is on my ToDo list in the near future. No idea what gears to go with.

I run 33x12.5 on a 15x10 ProComp 69 on my 4.0 daily driver.

My primary motivation is to get 5th gear back and hopefully improve mpg. I average about 12-13 and do about 50/50 highway and local roads.

4.56 is the usual recommended ratio for 33's with a 4.0 and 5-speed. Personally I'd go with that. I'd only consider 4.88 or 5.13 if you do lots of really tough trails or 35's are a distinct possibility.

 

[JoseA]

How does this translate over to a 5 speed manual? Regear is on my ToDo list in the near future. No idea what gears to go with.

I run 33x12.5 on a 15x10 ProComp 69 on my 4.0 daily driver.

My primary motivation is to get 5th gear back and hopefully improve mpg. I average about 12-13 and do about 50/50 highway and local roads.

I got 4.56 per Jerry's recommendation and I'm happy with that choice

 

[Brian.souhan]

4.56 is the usual recommended ratio for 33's with a 4.0 and 5-speed. Personally I'd go with that. I'd only consider 4.88 or 5.13 if you do lots of really tough trails or 35's are a distinct possibility.

I currently have 4.11s with 37 KO2s on aluminum rims (weight matters a lot) and need to go higher. But are there any concerns with running the engine at higher(ish) rpms? As I do a vast majority of highway driving, how high of rpms is high for a TJ I6? Growing up in the 80s, I remember oil commercials talking about smaller engines revving higher and working harder so needing better oil…so in my head (right or wrong - damn tv!), higher rpm is bad…and why I am not sure how high I should go, as it drives well with 4.11s, averaged 15.5 mpg going from DC to Toledo and back again weighed down at 4700lbs.

As a lot of my daily driving (and vast majority of overall mileage) is highway, I never thought to much about transmission temp, but that seems like it is an issue as well…does that hold true for manuals as well?

Thanks!

 

[Brian.souhan]

I currently have 4.11s with 37 KO2s on aluminum rims (weight matters a lot) and need to go higher. But are there any concerns with running the engine at higher(ish) rpms? As I do a vast majority of highway driving, how high of rpms is high for a TJ I6? Growing up in the 80s, I remember oil commercials talking about smaller engines revving higher and working harder so needing better oil…so in my head (right or wrong - damn tv!), higher rpm is bad…and why I am not sure how high I should go, as it drives well with 4.11s, averaged 15.5 mpg going from DC to Toledo and back again weighed down at 4700lbs.

As a lot of my daily driving (and vast majority of overall mileage) is highway, I never thought to much about transmission temp, but that seems like it is an issue as well…does that hold true for manuals as well?

Thanks!

Looks like the rev has already been answered in other threads. What about transmission temp on a manual? Assume with proper gearing for revs, should be no issue, but still curious if that will be impacted and what temp a manual transmission should run at…

 

[Jerry Bransford]

I currently have 4.11s with 37 KO2s on aluminum rims (weight matters a lot) and need to go higher. But are there any concerns with running the engine at higher(ish) rpms? As I do a vast majority of highway driving, how high of rpms is high for a TJ I6? Growing up in the 80s, I remember oil commercials talking about smaller engines revving higher and working harder so needing better oil…so in my head (right or wrong - damn tv!), higher rpm is bad…and why I am not sure how high I should go, as it drives well with 4.11s, averaged 15.5 mpg going from DC to Toledo and back again weighed down at 4700lbs.

As a lot of my daily driving (and vast majority of overall mileage) is highway, I never thought to much about transmission temp, but that seems like it is an issue as well…does that hold true for manuals as well?

Thanks!

Don't give the rpms a second thought, the 4.0 is more than up to any highway rpm you could stand driving at. I'd be running 5.13 with 37's and 5-speed and the rpms will be perfect on the highway. Odds are good your mpg will actually go up a tad with 5.13 with the engine operating more in its power band.

 

[Irun]

Thanks for the review. @DaveC and I are both planning 33s with 5.13s and the 42rle. I was considering going 5.38s, but I think the driveshaft speeds would be way too high to properly balance and be vib free.

That said, do you have any noticeable vibrations? This combo seems touchier with the Rubicon models but yours being an unlimited probably helps a lot.

The difference between 5.13 and 5.38 is probably 150 RPMs. If you have a rubicon, go 5.38!

 

[MikeE024]

When I wanted to re-gear with the 42RLE I was shocked at how low people told me to go. @Chris & @Jerry Bransford both claimed it would be the best set up with 33's and "OK" if I wanted to go to 35's in the future. (I am about 50/50 on going to 35's). I chose to listen to these guys and I'm very happy.

I've had 5.13's on my LJ for over a month and the gears have been paired with 33's for about 95% of that time. The previous owner had 32x10.5x16R on before me and the stock gears did very "OK" with that. I daily drive my Jeep and have taken it on a camping trip up to the Triny Mountains in Idaho, a round trip of about 450 Miles. So with daily driving and the trip, I have over 1,000 on the gears and figured id do a review to help people out given the 42RLE is a typical transmission in the later model TJ's.

I'll review aspects of the gears individually and driving experiences:

Daily Driving: My jeep is much more peppy and efficient. I never drove my LJ (Or any TJ) completely stock but it drives much better. Shifts smoother has better MPG and overall seems to like the gears more. It's just more pleasant to drive. The thing that sticks out the most is the fact that at a complete stop and in Drive I have to have my foot on the break because it will crawl on its own. It never did that with the old set up and I'm shocked at the amount of Tourqe I got back from the gears. I know this explanation isn't super detailed but I can't quite explain it...My jeep just drives better, that's all there is to it.

MPG: I'm not that surprised my MPG shot up. Unfortunately, I have a Roof Rack and my RTT on for pretty much the rest of the summer. However, I was able to get one full tank of gas tracked before the rack and tent went on...I track my fuel and with my old set up I averaged about 9.4 MPG (Since I bought it in December) daily driving. I should mention I have a hardtop and since I've owned the Jeep The heater has run about 80% of that time. Anyway, the one tank I tracked with the new gears came out to 14.7 MPG around town, an increase of over 5 Miles per gallon...I honestly think I could have gotten more if I had more tanks to track. I won't say much about my trips MPG because as you can see in the picture...I was pretty loaded down with gear and the wind was brutal on the way home. I averaged about 12.8 MPG with all the gear and my wife. I never took a camping trip like this with the old gears but the trips I did take it on...with no gear, rack, and wife ... it got about the same..slightly worse actually at about 12.2 MPG...So it's still impressive.

RPMs: Yes the RPMs run higher and that's the point. I won't say that much about my daily driving RPMs because where I live... I stay below 40 MPH 70% of the time and below 55 MPH 95% of the time. I rarely pay THAT close attention to them when I drive around town because I don't need to.
However, that's usually not why we re-gear our Jeeps...I posted two pictures from my trip below to give you an example of the RPMs. With all my gear and Jeep being even MORE top-heavy with the RTT I rarely go any faster than about 70-73 MPH. Even without the gear I never go fast than about 75-78 MPH. The first picture is what the RPMs look like at about 72 MPH in 4th (O/D) the second is when it downshifted into 3rd while still going 70. I LOVE the 2700-2800 range it sits at in 4th. Keeping the RPMs high has made it much more efficient and less mind-numbing shifting every 30 seconds.

The O/D Ratio & Shifting: Now, the re-gear doesn't fix the brutal O/D problem the 42RLE has. But, like stated above, it makes it MUCH more tolerable. The gears keep the RPMs higher and it helps with the shifting, performance, and fuel efficiency. I can attest to this pretty honestly given where I live. Nevada is America's most mountainous state and where I live in Elko (NE corner of the state) we sit at about 5,500 feet elevation. (Another reason why I was so picky with my gears). The 5.13s make driving through the hills and passes much more manageable and my jeep doesn't bog down nearly as much when the road gets steep or elevation shoots up. I feel like I have more "get-up" to tung me up the mountain.

Overall: I'm extremely happy I went with 5.13s given how I use my Jeep and where I live. Like Jerry and Chris have said time and time again on here, with the 42RLE and the nature of the 4.0 engine the deeper the gears the better. if you're thinking 5.13 is too much, don't, it's great and I 100% recommend it.

Hope this helps!!

View attachment 333914

View attachment 333916

View attachment 333917

Just wait till you make the OD auto-off on start up (it’s the cherry on top after a re-gear for us 42RLE folks).

I’m so damn happy now.

 

[MikeE024]

The difference between 5.13 and 5.38 is probably 150 RPMs. If you have a rubicon, go 5.38!

Indeed!

I would absolutely run 33s with my 5.38s. OD still falls off a cliff for me with 35s so much so that I only switch it on when going around 70+mph.

With 33s I’d imagine I’d switch OD on only once I’m around 63-65.

Otherwise, I believe rolling through town in 1-3 would be about 150-200 rpm higher iirc and that would likely still be under 3000 until you get around 57-60 mph is my guess based on my observations with 35s.

There is a calculator that I found in here (the forum) that is pretty spot on if you want to look for it. I think there were skulls on the page but I don’t recall the name of the website. It allows u to select your transfer case, transmission, gearing, and tire diameter. Then populate your speeds and different rpms or speeds iirc. Pretty handy website imo.

In short I would run 5.38s on 33s and enjoy it very much. The engine is very happy not lugging around like it did with 4.10s on 35s. Additionally, the engine-coolant temps have not raised one bit since the regear (using mopar engine-cooling parts).

 

[AndyG]

When I wanted to re-gear with the 42RLE I was shocked at how low people told me to go. @Chris & @Jerry Bransford both claimed it would be the best set up with 33's and "OK" if I wanted to go to 35's in the future. (I am about 50/50 on going to 35's). I chose to listen to these guys and I'm very happy.

I've had 5.13's on my LJ for over a month and the gears have been paired with 33's for about 95% of that time. The previous owner had 32x10.5x16R on before me and the stock gears did very "OK" with that. I daily drive my Jeep and have taken it on a camping trip up to the Triny Mountains in Idaho, a round trip of about 450 Miles. So with daily driving and the trip, I have over 1,000 on the gears and figured id do a review to help people out given the 42RLE is a typical transmission in the later model TJ's.

I'll review aspects of the gears individually and driving experiences:

Daily Driving: My jeep is much more peppy and efficient. I never drove my LJ (Or any TJ) completely stock but it drives much better. Shifts smoother has better MPG and overall seems to like the gears more. It's just more pleasant to drive. The thing that sticks out the most is the fact that at a complete stop and in Drive I have to have my foot on the break because it will crawl on its own. It never did that with the old set up and I'm shocked at the amount of Tourqe I got back from the gears. I know this explanation isn't super detailed but I can't quite explain it...My jeep just drives better, that's all there is to it.

MPG: I'm not that surprised my MPG shot up. Unfortunately, I have a Roof Rack and my RTT on for pretty much the rest of the summer. However, I was able to get one full tank of gas tracked before the rack and tent went on...I track my fuel and with my old set up I averaged about 9.4 MPG (Since I bought it in December) daily driving. I should mention I have a hardtop and since I've owned the Jeep The heater has run about 80% of that time. Anyway, the one tank I tracked with the new gears came out to 14.7 MPG around town, an increase of over 5 Miles per gallon...I honestly think I could have gotten more if I had more tanks to track. I won't say much about my trips MPG because as you can see in the picture...I was pretty loaded down with gear and the wind was brutal on the way home. I averaged about 12.8 MPG with all the gear and my wife. I never took a camping trip like this with the old gears but the trips I did take it on...with no gear, rack, and wife ... it got about the same..slightly worse actually at about 12.2 MPG...So it's still impressive.

RPMs: Yes the RPMs run higher and that's the point. I won't say that much about my daily driving RPMs because where I live... I stay below 40 MPH 70% of the time and below 55 MPH 95% of the time. I rarely pay THAT close attention to them when I drive around town because I don't need to.
However, that's usually not why we re-gear our Jeeps...I posted two pictures from my trip below to give you an example of the RPMs. With all my gear and Jeep being even MORE top-heavy with the RTT I rarely go any faster than about 70-73 MPH. Even without the gear I never go fast than about 75-78 MPH. The first picture is what the RPMs look like at about 72 MPH in 4th (O/D) the second is when it downshifted into 3rd while still going 70. I LOVE the 2700-2800 range it sits at in 4th. Keeping the RPMs high has made it much more efficient and less mind-numbing shifting every 30 seconds.

The O/D Ratio & Shifting: Now, the re-gear doesn't fix the brutal O/D problem the 42RLE has. But, like stated above, it makes it MUCH more tolerable. The gears keep the RPMs higher and it helps with the shifting, performance, and fuel efficiency. I can attest to this pretty honestly given where I live. Nevada is America's most mountainous state and where I live in Elko (NE corner of the state) we sit at about 5,500 feet elevation. (Another reason why I was so picky with my gears). The 5.13s make driving through the hills and passes much more manageable and my jeep doesn't bog down nearly as much when the road gets steep or elevation shoots up. I feel like I have more "get-up" to tung me up the mountain.

Overall: I'm extremely happy I went with 5.13s given how I use my Jeep and where I live. Like Jerry and Chris have said time and time again on here, with the 42RLE and the nature of the 4.0 engine the deeper the gears the better. if you're thinking 5.13 is too much, don't, it's great and I 100% recommend it.

Hope this helps!!

View attachment 333914

View attachment 333916

View attachment 333917

There is a simple mod In the how to section that will turn the overdraft off for you the first time you put the jeep in gear every time you drive and you can turn around and select overdrive by pressing the button so it essentially reverses the functionality.

 

[MikekiM]

I'm still in casual data acquisition mode since I am not ready to drop the coin on this mod.. yet.. but It is no less of a gameshow guess as to what ratio to choose..