4H Auto transfer case question

Rockmaninoff

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Anyone know if 4H Auto is mainly front wheel drive until traction is lost? Manual says:

2H
Rear Wheel Drive High Range — This range is for normal street and highway driving on dry, hard surfaced roads.

4H AUTO
Four-Wheel Drive Auto High Range — This range sends power to the front wheels. The four-wheel drive system will be automatically engaged when the vehicle senses a loss of traction. Additional traction for varying road conditions.


Also haven't seen the 5 position transfercase as an option. Is it export only?





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opsfox21

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It's late availability on automatic transmission Sahara only. It looks like this will send power to the rear axle primarily, as opposed to both at all times like many of us were hoping for.
 

Jeepsterfreak

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If you read the next page, it explains it better...


For variable driving conditions, the 4WD AUTO mode can
be used. In this mode, the front axle is engaged, but the
vehicle’s power is sent to the rear wheels. Four-wheel drive
will be automatically engaged when the vehicle senses a
loss of traction. Because the front axle is engaged, this
mode will result in lower fuel economy than the 2WD
mode.
 

bilash31

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Anyone know if 4H Auto is mainly front wheel drive until traction is lost
The simple answer to your question here is no. Jeeps are rear wheel drive vehicles primarily, with ability to send power to the front wheels.
 

foo.c

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It's late availability on automatic transmission Sahara only. It looks like this will send power to the rear axle primarily, as opposed to both at all times like many of us were hoping for.
It might send some power to the front even in dry conditions without wheel spin detected. I think all these 1/2 ton truck system work about the same and I know both Ford and Chevy systems do that.
 

opsfox21

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It might send some power to the front even in dry conditions without wheel spin detected. I think all these 1/2 ton truck system work about the same and I know both Ford and Chevy systems do that.
Yeah, I would prefer 50/50 under normal conditions, best stability on ice and snow. The way the manual explains it, as posted above, leads me to suspect otherwise though. At least it notes that the front axle stays engaged, so the delay in power delivery should be shorter than with these other CUV AWD systems that disconnect the front or rear axle for fuel efficiency.
 

The Great Grape Ape

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Another example of poor writing in the manual. unfortunately with conflicting power to the front then power to the back descriptions.

They always could’ve changed the default delivery from RWD to FWD, but that would seem like beyond another level of additional change unneeded in order to add FT 4WD.

As the TransferCase is the MP3022, we know it defaults to RWD even in 4Auto mode.

Hoping for greater detail on this particular implementation and things like its torque split (was 42/58) vs implementations on the Cherokee, Liberty, etc.
 
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Thanks for all the replies.

If you read the next page, it explains it better...


For variable driving conditions, the 4WD AUTO mode can
be used. In this mode, the front axle is engaged, but the
vehicle’s power is sent to the rear wheels. Four-wheel drive
will be automatically engaged when the vehicle senses a
loss of traction. Because the front axle is engaged, this
mode will result in lower fuel economy than the 2WD
mode.
Missed that one. Is the JL more efficient in 2H than the JK in 2H? I remember reading somewhere that the front part of the driveshaft rotates in the JK on 2H although it's disconnected at the front diff. Never checked beyond that.
 

foo.c

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Since the JK front axle doesn't have unlocking hubs, both axles are always turning and the front diff is always doing it's thing allowing the axles to turn at different speeds.

It sounds like JL has 1 unlocking axle, so only one axle will be turning and the diff will just free spin.
 

Jeepsterfreak

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Since the JK front axle doesn't have unlocking hubs, both axles are always turning and the front diff is always doing it's thing allowing the axles to turn at different speeds.

It sounds like JL has 1 unlocking axle, so only one axle will be turning and the diff will just free spin.
Can you please explain further?

Wouldn't the front axle and front drive shaft always be spinning? The disconnect is in the TC across all trims.
 

foo.c

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Can you please explain further?

Wouldn't the front axle and front drive shaft always be spinning? The disconnect is in the TC across all trims.
Think old school 4x4 with locking hubs.

You can put the TC in 4 hi or low, but unless you lock the hubs only the back wheels will actually apply power to the ground. Also, you have to lock both hubs or the axle with the hub unlocked will get all the power (unless you have a diff locker engaged). Jeep eventually did away with manually locking hubs, and unlocking hubs altogether.

In search of fuel mileage they are kind of going back to the future, but with an axle disconnect instead of a hub. So 4auto connects both axles so that the TC can actually apply power to the front according to its algorithm (it's computer controlled).
 

Johnbuz

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It's late availability on automatic transmission Sahara only. It looks like this will send power to the rear axle primarily, as opposed to both at all times like many of us were hoping for.
Do you have any evidence the selectrac is only for automatic transmissions? I have ot seen any such evidence.
 

ThirtyOne

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Do you have any evidence the selectrac is only for automatic transmissions? I have ot seen any such evidence.
The order guide does not restrict it to automatic. It could be an error.
 

opsfox21

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Do you have any evidence the selectrac is only for automatic transmissions? I have ot seen any such evidence.
No evidence, just going by past practice on every Jeep that has ever had SelecTrac or something similar for the last three decades.
Not counting FWD based vehicles.

I’d love to be wrong in this case though, I’d probably get that configuration.
 

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