Diesel JT Ready For New Gears ⚙️

[earthemigrant]

I am making plans to run down south to rebel off-road for a regear on the diesel gladiator. I come here seeking advice.

I am currently sitting on roughly a 4” lift and running 37” baja boss mt. My inclination is to go with 4.56. However there is the possibility I could go 38x13.5 down the road.

Can anyone with experience please tell me what the real world difference is between 4.56 and 4.88 when running these tire diameters.

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[rharr]

I suggest you do some searching there is quite a few threads on the topic and even one thread that has healthy debate about the right gears for the ECO D. Let's leave this can of worms closed.

On that note, if you are paying a shop to do the work, let them figure what gears to use.

 

[Jteakus]

I have 38x13,50r17's and the plan is to install 4.10's.
I have a notebook page of math if you want me to elaborate on why I am going with this ratio vs 4.56's.

 

[JT1]

I am making plans to run down south to rebel off-road for a regear on the diesel gladiator. I come here seeking advice.

I am currently sitting on roughly a 4” lift and running 37” baja boss mt. My inclination is to go with 4.56. However there is the possibility I could go 38x13.5 down the road.

Can anyone with experience please tell me what the real world difference is between 4.56 and 4.88 when running these tire diameters.

Do you tow? How heavy is your build? How fast do you routinely drive?

I wouldn't consider 4.88s unless 40+ was in your future and you don't plan on changing the 44s for a different axle combo.

If you drive faster (80-85+) for hours on end, do the 4.10s. If you don't, or you tow, or your rig is heavy, do the 4.56's.

Offroad with the 4:1 transfer case, they will both be fine.

 

[earthemigrant]

I suggest you do some searching there is quite a few threads on the topic and even one thread that has healthy debate about the right gears for the ECO D. Let's leave this can of worms closed.

On that note, if you are paying a shop to do the work, let them figure what gears to use.

Well then why are any of us here? What’s the point of this? They should probably shut the forum down and make it a searchable archive. Better yet we can just ask our AI overlords. They were trained on all these forum posts. They know the answers better than we do.

The whole point of the forum is to discuss this nonsense over and over and over. Otherwise there is no reason for a forum to exist. Do you have anything to ad or are you here to play hall monitor?

 

[earthemigrant]

Do you tow? How heavy is your build? How fast do you routinely drive?

I wouldn't consider 4.88s unless 40+ was in your future and you don't plan on changing the 44s for a different axle combo.

If you drive faster (80-85+) for hours on end, do the 4.10s. If you don't, or you tow, or your rig is heavy, do the 4.56's.

Offroad with the 4:1 transfer case, they will both be fine.

I tow a kayak trailer often in the summer. Fairly lightweight trailer. 4 13-17ft kayaks. I’m generally not heavy. Less than 400lbs loaded.

I am not going bigger than 38s and I don’t drive extended periods at 80-85 mph very often.

Thank you this is exactly the kind of information I am looking for.

 

[earthemigrant]

I have 38x13,50r17's and the plan is to install 4.10's.
I have a notebook page of math if you want me to elaborate on why I am going with this ratio vs 4.56's.

Yes please. I would be interested to know why you are gong that way.

 

[rharr]

Well then why are any of us here? What’s the point of this? They should probably shut the forum down and make it a searchable archive. Better yet we can just ask our AI overlords. They were trained on all these forum posts. They know the answers better than we do.

The whole point of the forum is to discuss this nonsense over and over and over. Otherwise there is no reason for a forum to exist. Do you have anything to ad or are you here to play hall monitor?

I am sorry you feel that way. Best of luck on your endeavors

 

[Jteakus]

I've got a 2020 JL Rubicon Diesel. I put it on 315's at about 5K miles. I do not tow with it. It gets high 20's mpg every tank. it has 85K miles on it.
I have a 2022 JT with a roof rack, bed rack, iKamper, fridge and enough gear to camp for 2 weeks. It is heavy and is on 38's. Last trip I took was over 3K miles and I averaged 22 mpg.
Both Jeeps have original 3.73 gears. I am not regearing the JL but am going with 4.10's in the JT.

 

[Jteakus]

Here is what I’ve come up with.

 

[Jteakus]

As you can see the JL is down 80 rpm at 75 mph which is where I drive on the interstate. The JT with 4.10’s will put me down only 29 rpm. I think that will be very acceptable. A 4.30 gear would be perfect but not available. The more rpm you turn the more your mileage will suffer. The diesel makes so much torque at low rpm it would be a shame to keep it above the torque range.
You can see how the gears and tires play with each other from my examples.

 

[Jteakus]

I will add that at 75 mph my JL likes to be real close to 2K rpm. if you tow or stay at high altitude the 4.56 may be a better choice with 38's

 

[Rusty PW]

Happy reading.

https://www.jeepgladiatorforum.com/forum/threads/swapping-up-to-the-4-10s.95025/

https://www.jeepgladiatorforum.com/forum/threads/jtrd-on-37-what-ratio-4-56-or-4-88.88629/

https://www.jeepgladiatorforum.com/forum/threads/re-gear-jt-rubi-on-38-40s.81512/#post-1325638

 

[3VOLVE]

I ran 4.10s (axles from a gas JTR) on my previous JTRD on MT 37s and towed a Patriot X3 camper all over. Mileage improved to low 20s towing and I had no problems maintaining speed. Unladen, I averaged 22-23.t mpg per tank, depending on speed.

Your 38s will likely measure out closer to actual 37” when installed.

 

[Wheelin98TJ]

As you can see the JL is down 80 rpm at 75 mph which is where I drive on the interstate. The JT with 4.10’s will put me down only 29 rpm. I think that will be very acceptable. A 4.30 gear would be perfect but not available. The more rpm you turn the more your mileage will suffer. The diesel makes so much torque at low rpm it would be a shame to keep it above the torque range.
You can see how the gears and tires play with each other from my examples.

Nitro makes a 4.30 ratio for the Advantek axles.

https://eastcoastgearsupply.com/i-2...MqlTMK6cK3MrocIiA0RCBoUAeUTSfgSLJhnv5bH1ar5L4

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