Yet another regearing question

[DonaldJ001]

Hello all, I searched the forums and couldn’t find exactly what I was looking for.

Current situation:
JT Rubicon with 4:10 gear ratio
Gas with Automatic transmission
Soon upgrading to 37” tires
Regularly tow a trailer with firewood (3000 pounds)
Regularly tow an offgrid trailer (2500 pounds) with some off-road.
Live in MI so mostly flat land but occasional trips out west with mountains and elevation.

I’m not an acceleration fiend and don’t need ultra high acceleration performance. But I would like to be able to go to hills more, get better mileage when towing, and not be pegged at 5000 RPM . The long distance mileage is important. It adds up.

what should I regear to? What gear manufacturers do you recommend? Me and a friend will be doing Labor.

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[JT1]

5.13s are the answer. 5.38s if you are going to tow all the time at elevation.

 

[Wheelin98TJ]

5.13

 

[DuckTruck7]

I am absolutely new here. I'm not a gearhead but appreciate those that are. So humbly, I ask, what is this re-gearing about? I tow a drift boat in West Michigan and just the simple hills here makes me think that the truck is overworking at 3800 RPM. ANy help appreciated.

 

[Wheelin98TJ]

I am absolutely new here. I'm not a gearhead but appreciate those that are. So humbly, I ask, what is this re-gearing about? I tow a drift boat in West Michigan and just the simple hills here makes me think that the truck is overworking at 3800 RPM. ANy help appreciated.

Regearing is done to change the torque multiplication at the axle.

Stock ratios are 3.73 or 4.10. Regearing from 4.10 to 5.13 is a 25% change in the final drive ratio. You will have 25% more torque multiplication. You will also turn 25% more RPM at the same speed.

I think the 10 speed bike analogy explains it well. Hard to pedal going uphill is like 4.10 gears with 37" tires. Shifting the bike to make it easier to pedal is like 5.13 gears. But with the easier to pedal gear, you have to make more pedal revolutions to go the same distance.

 

[JT1]

I am absolutely new here. I'm not a gearhead but appreciate those that are. So humbly, I ask, what is this re-gearing about? I tow a drift boat in West Michigan and just the simple hills here makes me think that the truck is overworking at 3800 RPM. ANy help appreciated.

Your Jeep will have either 3.73 or 4.10 axle gears. When you add bigger tires and/or a lift, you change axle gears to compensate. With an automatic, 35's and 4.56 or 4.88s. With 37's, 4.88 or 5.13.

 

[DonaldJ001]

That’s similar to how I explain it to friends. You selecting gears is the transmission… changing that front gear size is like regearing

 

[DonaldJ001]

So those in the know, what is a solid and reliable manufacturer for aftermarket gearing?

 

[Wheelin98TJ]

So those in the know, what is a solid and reliable manufacturer for aftermarket gearing?

Dana Spicer for Dana axles.

 

[DuckTruck7]

Regearing is done to change the torque multiplication at the axle.

Stock ratios are 3.73 or 4.10. Regearing from 4.10 to 5.13 is a 25% change in the final drive ratio. You will have 25% more torque multiplication. You will also turn 25% more RPM at the same speed.

I think the 10 speed bike analogy explains it well. Hard to pedal going uphill is like 4.10 gears with 37" tires. Shifting the bike to make it easier to pedal is like 5.13 gears. But with the easier to pedal gear, you have to make more pedal revolutions to go the same distance.

Ahhh - So it’s easier in the Jeep pulling a trailer up a mountain out west but the RPM’s are higher??

 

[DuckTruck7]

Your Jeep will have either 3.73 or 4.10 axle gears. When you add bigger tires and/or a lift, you change axle gears to compensate. With an automatic, 35's and 4.56 or 4.88s. With 37's, 4.88 or 5.13.

How do I find out what gearing my Jeep has? It’s an Overland Edition 2020. 18 inch wheels. I just put on some Hankook Dynapro AT2’s.

 

[Vtur]

How do I find out what gearing my Jeep has? It’s an Overland Edition 2020. 18 inch wheels. I just put on some Hankook Dynapro AT2’s.

3.73

 

[Blade1668]

How do I find out what gearing my Jeep has? It’s an Overland Edition 2020. 18 inch wheels. I just put on some Hankook Dynapro AT2’s.

You can check the build sheet or window sticker. A Rubicon or Max-Tow (Mojave??) has 4:10 Sport, Sport S and Overland have 3:73 as standard. All diesel engine equipped have 3:73 in all as far as I know. Another method is jack up rear end then in neutral rotate tire count revolutions. A PTA. method.

 

[bleda2002]

Ahhh - So it’s easier in the Jeep pulling a trailer up a mountain out west but the RPM’s are higher??

Not necessarily because the transmission has 2 overdrives in 7th and 8th. Regearing gives you more grunt and the ability for the transmission to use more gears at higher loads.

This helps you use a higher gear for the same amount of wheel torque which often means a lower rpm.

 

[1550jrit]

I’ve run 5.38’s and 37’s for the past 6k miles. It’s super drivable and not too deep in my opinion. Based on what you’ll be towing, you’ll appreciate the additional depth. 5.13 vs 5.38 is only a 4% difference. If you told me you’d rarely tow, then I’d agree that 5.13 would suffice. My gears are Dana Spicer and set up perfectly the first attempt, no additional shimming needed. Just my 2 cents, good luck with whatever you decide.

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