Rear axle ratio vs. Overall top gear ratio

[operator22]

Apologies if this is a stupid question but I'm trying to educate myself. My '21 Willys came with a 3.45 "overall top gear ratio". My new Rubicon has 4.1 "rear axle ratio". Both have the 2.0T engine. I like the acceleration with the 4.1 but miss the lower RPM and better fuel economy of the Willys on the highway.

Question: what does the difference in the nomenclature actually mean?

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[autotragic]

There is no difference, the right hand didn't talk to the left hand and now they use two completely different terms to say the same thing. Just one of those things.

The available gear ratios from the factory for the JL are/have been 3.45, 3.73, 4.10, 4.56, 4.88.

3.45s are the fuel economy gear for Sports and Saharas. Diesels and non XR 392s got 3.73 gears. Rubicons get 4.10s as standard with 4.88s optional with a manual transmission. XR package automatically got 4.56 gears. Pre 2024 Willys got 3.45s but 2024+ Willys gets 4.10s unless it's an XR then it also gets 4.56s.

Nomenclature doesn't change anything.

 

[azwjowner]

Those both refer to the axle gear ratio, which is the number of times the driveshaft has to turn for the axles (wheels) to turn once.

The driveshaft goes from the transmission to the axles, so if you increase the gear ratio from 3.45 to 4.10, you are requiring the driveshaft to spin more for the same rotation of the wheels.

The driveshaft spins more by having either a lower transmission gear or higher engine RPM.

 

[operator22]

Those both refer to the axle gear ratio, which is the number of times the driveshaft has to turn for the axles (wheels) to turn once.

The driveshaft goes from the transmission to the axles, so if you increase the gear ratio from 3.45 to 4.10, you are requiring the driveshaft to spin more for the same rotation of the wheels.

The driveshaft spins more by having either a lower transmission gear or higher engine RPM.

Thank you. This makes sense. Does the number (3.45 or 4.1) change depending on which gear the vehicle is in?

 

[azwjowner]

Thank you. This makes sense. Does the number (3.45 or 4.1) change depending on which gear the vehicle is in?

No. These are fixed gears inside the axles. When I regeared my manual transmission JL from 3.45 to 4.56, my engine RPMs are now 32 percent higher in every transmission gear at the same speed.

 

[Lofty]

For a 3.45 ratio the driveshaft spins 3.45 times to rotate the wheels one revolution.
For a 4.10 ratio the driveshaft spins 4.10 times to rotate the wheels one revolution.
This verbiage can be used for all ratios. Generally, the lower the ratio numerically the lower the engine RPM'S will be and the better gas mileage one should get.

 

[Bandit59]

Apologies if this is a stupid question but I'm trying to educate myself. My '21 Willys came with a 3.45 "overall top gear ratio". My new Rubicon has 4.1 "rear axle ratio". Both have the 2.0T engine. I like the acceleration with the 4.1 but miss the lower RPM and better fuel economy of the Willys on the highway.

Question: what does the difference in the nomenclature actually mean?

Gas mileage gears r that. Keeping your roms down. 4:10 is a more performance option but turns engine more rpms. Hard to have both

 

[Gunfighter]

There is no difference, the right hand didn't talk to the left hand and now they use two completely different terms to say the same thing. Just one of those things.

The available gear ratios from the factory for the JL are/have been 3.45, 3.73, 4.10, 4.56, 4.88.

3.45s are the fuel economy gear for Sports and Saharas. Diesels and non XR 392s got 3.73 gears. Rubicons get 4.10s as standard with 4.88s optional with a manual transmission. XR package automatically got 4.56 gears. Pre 2024 Willys got 3.45s but 2024+ Willys gets 4.10s unless it's an XR then it also gets 4.56s.

Nomenclature doesn't change anything.

Don't forget - The High Altitude gets 3:73's (gas motors & diesel) with the Dana 44 axles front and rear.

 

[Bandit59]

Don't forget - The High Altitude gets 3:73's (gas motors & diesel) with the Dana 44 axles front and rear.

Mine only has 345 which is standard and pretty sure Dana44 is not standard

 

[Gunfighter]

You have the High Altitude? All of them that had the diesel or gasser came standard with 3:73 and Dana 44 axles front and rear.

 

[Bandit59]

You have the High Altitude? All of them that had the diesel or gasser came standard with 3:73 and Dana 44 axles front and rear.

Acording to my sticker it does not. Bought it new. Has the 20 inch wheels and the creature comforts. Wished it did

 

[Gunfighter]

Acording to my sticker it does not. Bought it new. Has the 20 inch wheels and the creature comforts. Wished it did

If you have a true "High Altitude" it WILL have the Dana 44 axles and 3:73 gears.

Your signature shows you have a 4XE - that definately comes with the 3:73 gears and Dana 44 axles regardless (4XE Rubicon has 4:10) : https://www.jeep.com/model-compare....2TV|CUJ202417JLXS74B,2TY|CUJ202417JLXT74A,2TN

 

[Bandit59]

If you have a true "High Altitude" it WILL have the Dana 44 axles and 3:73 gears.

Your signature shows you have a 4XE - that definately comes with the 3:73 gears and Dana 44 axles regardless (4XE Rubicon has 4:10) : https://www.jeep.com/model-compare....2TV|CUJ202417JLXS74B,2TY|CUJ202417JLXT74A,2TN
Not a 4 xe. I had one never again

 

[Bandit59]

If you have a true "High Altitude" it WILL have the Dana 44 axles and 3:73 gears.

Your signature shows you have a 4XE - that definately comes with the 3:73 gears and Dana 44 axles regardless (4XE Rubicon has 4:10) : https://www.jeep.com/model-compare....2TV|CUJ202417JLXS74B,2TY|CUJ202417JLXT74A,2TN

 

[Bandit59]

If it does not on the sticker so I say it doesnt

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