Auto options

[Coojeebear]

2 days of snow for my Rubicon's first experience. I have a 2022 Rubicon petrol auto. I've like to be sure that I have my head around the 4x4 settings. The the transfer box I have 4x4 auto & 4x4 Part time. The wording does not make sense of my understanding.

 

I think 4x4 auto means rge 4x4 is in something like 20/80 front back & adjusts the 4x4 ratio as it detects slippage.

 

I think 4x4 part time means that it is fix 1:1 & not adjustable?

 

 

[V]

As far as I know with your Jeep that sounds about right. The thing to remember about 'Part Time' is that you can only use it part of the time when conditions require it.

 

In Land Rover speak it is high ratio four wheel drive with the diff lock engaged. On Jeep transfer cases Part Time always locks the front and rear outputs together. In Auto mode the front and rear outputs can operate at the same or different speeds which is necessary on high traction surfaces like tarmac roads.

 

See how you get on with Auto mode on snow particularly if you've not used part time or low ratio before. Experiment shifting in and out of part time on straight roads before using on low traction curves. 

[digger]

V is correct. The key point is you must not use 'part time' on any  high grip surface such as dry roads.

[AlexK]

JL Selec-Trac, which is effectively what all Euro-spec Wranglers have, is different to the Selec-Trac system of old. In 4Auto, the transfer case sends power to the rear wheels only in normal driving, unless the system detects wheel slippage at which point it engages the front axle.

 

It uses the MP3022 transfer case from the Liberty with an electronically-controlled clutch.

[Overlander21]

A few pages from the manual, if it helps @Coojeebear

 

[V]

6 hours ago, digger said:

The key point is you must not use 'part time' on any  high grip surface such as dry roads.

For the majority of drivers this is true and good advice for preventing transmission or driveline damage. In Part Time mode the driver is responsible for preventing transmission or driveline damage caused by wind-up. In Full-Time or 4Auto, the centre differential eliminates this problem for you.

 

However, there are ground conditions where Part Time can be used safely on a high traction surface if the driver knows how to prevent wind-up and release wind-up before it becomes a problem. Can you think of any?

[JimC]

2 hours ago, V said:

However, there are ground conditions where Part Time can be used safely on a high traction surface if the driver knows how to prevent wind-up and release wind-up before it becomes a problem. Can you think of any?

Driving on an ice covered lake

[V]

Ice isn't exactly high traction, but a good use of part-time mode.

 

Launching a boat from a trailer or recovering a boat to a trailer down a concrete slipway in either low ratio or part-time high ratio.

In any situation where you need to use engine braking distributed over four tyres instead of two or particularly on the front tyres.

Not very likely, but possibly for an emergency, driving up or down outdoor pedestrian steps in low ratio.

Driving on to a car transporter (recovery trucks usually winch)

Driving on roads under trees where snow has fallen in gaps creating alternating sections of snow/ice and tarmac.

My favourite, driving on sandstone rock in Moab, Utah.

[Raakhee]

I've never used 4H-part time. Kinda skipped over it to 4-Low at Walters.

I drove around in 4H-Auto yesterday as most of the roads around me were not gritted. I only got up to 30mph and the Jeep was steady on the road. 

I think next JOC event I'll try out 4H-part time. Best to know all the gear ratios in a safe environment 

[V]

If you find yourself on a road packed with snow or ice, you could try it then. Don't be afraid to switch in and out of part-time and 4auto, even if you use part-time for only a few seconds. As long as there is sufficient tyre slip between the front and rear axles, any wind-up will be released when the tyres lose grip or when you shift back to 2wd. The purpose of part-time is to transmit power through as many tyres as possible when grip on those tyres is less than ideal. For Jeeps that don't have real full-time 4wd, part-time is useful when engine braking on the normally non-driven axle is required.

[UKTJ]

It all seems terribly complicated.  Makes me wonder how many new Wrangler owners understand all the various modes.

[Raakhee]

40 minutes ago, UKTJ said:

It all seems terribly complicated.  Makes me wonder how many new Wrangler owners understand all the various modes.

We don't understand. Which was my whole argument for a physical Users Handbook. However we also need a practical demo of the functions and salesman at dealership don't normally know and neither can you go off roading on the test drive.

I honestly can't thank Terry Bonner enough for the 4x4 lesson. He built my confidence. So much so that I agreed to go rock climbing with @CandsEvo7 and then do Strata Florida

[UKTJ]

2 hours ago, Raakhee said:

We don't understand. Which was my whole argument for a physical Users Handbook. However we also need a practical demo of the functions and salesman at dealership don't normally know and neither can you go off roading on the test drive.

I honestly can't thank Terry Bonner enough for the 4x4 lesson. He built my confidence. So much so that I agreed to go rock climbing with @CandsEvo7 and then do Strata Florida

It wasn't a pop at you @Raakhee, apologies if that is how it came across.  I was thinking about those who do not have the benefit of JOC and the amazing support and knowledge transfer that the more experienced members provide.*

I 100% agree that it would be good if dealers had at least one person who understands the vehicles they are selling and can provode a good grounding to buyers.  To be honest I had not appreciated the level of complexity and subtlety of the choices available to owners of new Wranglers, getting a sense of that from this thread is what made me think about how well understood they are.  Maybe it is about the structure of the dealer network, or maybe it is because they know their customers and know the vast majority won't go much further offroad than a grass verge on a narrow lane

 

* Whilst my old TJ is a lot less complex than a JL, there are still things to learn.  I was very grateful to be told how I could disable the function where the clutch needs to be depressed to start, in order that I could better deal with a failed hillclimb scenario.  I am 99% sure I would not have found that out witjout this forum.

Edited December 11, 2022 by UKTJ

[Coojeebear]

On 10/12/2022 at 01:01, V said:

As far as I know with your Jeep that sounds about right. The thing to remember about 'Part Time' is that you can only use it part of the time when conditions require it.

 

In Land Rover speak it is high ratio four wheel drive with the diff lock engaged. On Jeep transfer cases Part Time always locks the front and rear outputs together. In Auto mode the front and rear outputs can operate at the same or different speeds which is necessary on high traction surfaces like tarmac roads.

 

See how you get on with Auto mode on snow particularly if you've not used part time or low ratio before. Experiment shifting in and out of part time on straight roads before using on low traction curves. 

Thank you

 

Are the diff locks not different on the Rubicon? I thought for diff locks I have to use LOW. Driving on fully snow covered roads, I was out yesterday using mostly auto. It did not feel as "planted" as my old TJ, but to be fair - it did not slip. I used Part time for difficult hills. I was never able to engage diff lock as it wasnt viable to go that slowly.

[TimC]

1 hour ago, Coojeebear said:

Thank you

 

Are the diff locks not different on the Rubicon? I thought for diff locks I have to use LOW. Driving on fully snow covered roads, I was out yesterday using mostly auto. It did not feel as "planted" as my old TJ, but to be fair - it did not slip. I used Part time for difficult hills. I was never able to engage diff lock as it wasnt viable to go that slowly.

 

He means the central transfer case diff lock rather than the axle diff locks. You are right, the Rubicon Dana E lockers can only be engaged in 4 low.

[V]

1 hour ago, TimC said:

You are right, the Rubicon Dana E lockers can only be engaged in 4 low.

Is that a configurable option default or is it hard wired that way?

 

A locked rear axle differential in high ratio would be like having a spool in a drag race car.

[Raakhee]

19 minutes ago, V said:

Is that a configurable option default or is it hard wired that way?

 

A locked rear axle differential in high ratio would be like having a spool in a drag race car.

I think it's not selectable in 4-High. It's literally a button you push. If the conditions are not right it will not engage. 

[Raakhee]

From the User handbook

 

[TimC]

1 hour ago, V said:

Is that a configurable option default or is it hard wired that way?

 

A locked rear axle differential in high ratio would be like having a spool in a drag race car.

I think it’s hardwired. Same with the swaybar disconnects and seatbelt warning and possibly hill descent control, you can only select them if you’re in 4 Low. I’m sure it must be possible to fool the system though, it’s probably just a switch somewhere on the transfer gears shifter. I bet it could just be linked out.

[Raakhee]

Actually Swaybar disconnect can be selected in 4-high. However it will reconnect if you exceed 18mph.

[TimC]

7 hours ago, Raakhee said:

Actually Swaybar disconnect can be selected in 4-high. However it will reconnect if you exceed 18mph.

Ah, thanks @Raakhee I thought I might have been wrong on one of those, couldn’t remember which one. Thought it might be hill descent, thanks for the correction.

[Raakhee]

Yep. Hill decent will only activate on 4-Low