2H vs 4H

[jeepoch]

The information you presented is EXCELLENT--Thank you! Please forgive my question. I should probably know the answer but I am confused about when to use 2H in a Rubicon 392.
I literally just picked it up at dealership yesterday. The salesman told me to leave it in 4H auto for normal highway driving.
Other less robust (also now recognize wrongly named) 4WD vehicles I've owned were normally driven on paved roads or highways in 2WD. If inclement weather or slippery conditions existed I'd always shift into 4WD.
My assumption is that less horrible gas mileage might be achieved in 2H?
What is your advice as to normal roads, dry conditions? 2H or 4H in Rubicon 392?

Thanks for your great comment!

Randy,

You lucky duck. The 392 has the best transfer case found in any Wrangler. My lowly Sport could only drool over what you have.

First off, your 392 and most Rubicon's comes standard with the 'Rock-Trac' Transfer case which hides the fact that you have 2WD. It instead has Auto/Partial 4Hi. In this mode the transfer case automatically selects either 2 or 4WD based on any wheel slip. On dry pavement it acts just like any AWD system and provides power to just a single axle. However, if it detects any difference in rotational speed on any of the four wheels it silently and automatically will select 4Hi (power on both axles) for you, no selection or interaction required.

Recall, you still have open diffs until you manually engage your lockers, but any of your 4 wheels can automatically be powered without you ever thinking about it.

For the rest of us poor souls with just the Select-Trac transfer case, we have to shift from 2Hi to 4Hi manually. So you can think of your vehicle has having not only an automatic transmission (which by the way is also one of the best on the planet) but also an automatic transfer case as well.

You however like the rest of us, need to still select 4Lo in specific conditions which warrant the lower gear ratio. But this too the Rock-Trac rules. It provides a much lower 4.0 : 1 ratio to our piddly 2.72 : 1 gearing. This gives you even more torque when crawling over the tallest of boulders (likely like Super-Man, in a single bound).

Enjoy your system. I'm jealous as hell.

Yet, I hope you wave to me on some high-altitude mountain pass here in Colorado sometime. It's amazing how capable my 2 door lifted Sport on 35's really is. Someday I'll hit the lottery and be able to afford something with lockers.

I can dream... You can just enjoy.

Regards,
Jay

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[Jeepsmashin]

I only use 4H when I need it, if I'm driving on trails and the tires aren't slipping I'll stay in 2H. You can feel it when you need 4H

For water crossing and deep puddles I use 4H, I don't want to get stuck then switch back to 2H when out.

Heavy snow and it's not plowed 4H, driving on ice your screwed even in 4H lol. I came down a trail and it was iced, i was sliding and had little to no control driving 1-2mph and just sliding every where.

 

[Bo Ran]

Randy,

You lucky duck. The 392 has the best transfer case found in any Wrangler. My lowly Sport could only drool over what you have.

First off, your 392 and most Rubicon's comes standard with the 'Rock-Trac' Transfer case which hides the fact that you have 2WD. It instead has Auto/Partial 4Hi. In this mode the transfer case automatically selects either 2 or 4WD based on any wheel slip. On dry pavement it acts just like any AWD system and provides power to just a single axle. However, if it detects any difference in rotational speed on any of the four wheels it silently and automatically will select 4Hi (power on both axles) for you, no selection or interaction required.

Recall, you still have open diffs until you manually engage your lockers, but any of your 4 wheels can automatically be powered without you ever thinking about it.

For the rest of us poor souls with just the Select-Trac transfer case, we have to shift from 2Hi to 4Hi manually. So you can think of your vehicle has having not only an automatic transmission (which by the way is also one of the best on the planet) but also an automatic transfer case as well.

You however like the rest of us, need to still select 4Lo in specific conditions which warrant the lower gear ratio. But this too the Rock-Trac rules. It provides a much lower 4.0 : 1 ratio to our piddly 2.72 : 1 gearing. This gives you even more torque when crawling over the tallest of boulders (likely like Super-Man, in a single bound).

Enjoy your system. I'm jealous as hell.

Yet, I hope you wave to me on some high-altitude mountain pass here in Colorado sometime. It's amazing how capable my 2 door lifted Sport on 35's really is. Someday I'll hit the lottery and be able to afford something with lockers.

I can dream... You can just enjoy.

Regards,
Jay

Jay, thank you so much for this clear explanation. You are most kind. And should I ever have the opportunity to drive my Jeep to Colorado, I'll likely be waving at you from down below wondering how you got way up there. I'm sure it would be incredible.
Until then, I'll have to settle for some beginner's kiddie ride I might find here in DFW area just to learn how to keep the wheels under me. But eventually . . .

 

[txj2go]

Jay, thank you so much for this clear explanation. You are most kind. And should I ever have the opportunity to drive my Jeep to Colorado, I'll likely be waving at you from down below wondering how you got way up there. I'm sure it would be incredible.
Until then, I'll have to settle for some beginner's kiddie ride I might find here in DFW area just to learn how to keep the wheels under me. But eventually . . .

It's only 12 hours to Denver then not far beyond that to some good trails. It's a little more than that to Durango/Silverton, and only 19 hours to Moab. 2021 I did Colorado trails 2 trips and Utah trails 3 trips.

 

[TheBirdie72]

Rhode Island right now… 4H in this, definitely

 

[Ratbert]

...
First off, your 392 and most Rubicon's comes standard with the 'Rock-Trac' Transfer case which hides the fact that you have 2WD.
...

Standard on most Rubicons??

 

[jeepoch]

Standard on most Rubicons??

Whoops, strike the word most.

Tough crowd.

 

[jeepoch]

Whoops, strike the word most.

Tough crowd.

But to be fair - there are two different models of the Rock-Trac Transfer Case:

• The Rock-Trac on the Rubicon has 4 positions and a 4:1 low range in "4L".
• The Rock-Trac Full time on the Rubicon has 5 positions (including 4H AUTO) and a 4:1 low range in "4L".

 

[Ratbert]

Whoops, strike the word most.

Tough crowd.

Isn't it only standard on the 392?

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