What exactly is the 2.72:1 Selec-Trac® Full-Time 4WD System

[Zombienation]

Hey guys, apologize for the ignorance but what exactly is the 2.72:1 Selec-Trac® Full-Time 4WD System that is standard on the 4xe Sahara?

(tl;dr when can I use it?)

Coming from a mustang gt I am not familiar with Jeep’s 4 wheel drive options. I was always told you can only use Jeep’s 4 wheel on very wet, sandy, or snowy roads or you will cause damage. Reading up on selec trac sounds like you can run it in 4H with no issue more than that.

Not planning on driving 4wheel in the dry but on a cold potential black ice morning in the winter am I good with 4H even though the road will be mostly dry?

thanks!!

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[Echo4papa]

You can drive in 4H Auto on dry paved surfaces. It will only send power to the front wheels when it senses the rear losing traction.

Seems to be a few of us here that came from the S550. I had a 2015 GT, then a 2019 GT before my 4xe Sahara.

 

[ChrisTheGod]

I have that option I regret getting it now I thought it turned the stick into a newer knob like device nope it’s just stupid in my opinion.

 

[GATORB8]

You can drive in 4H Auto on dry paved surfaces. It will only send power to the front wheels when it senses the rear losing traction.

Seems to be a few of us here that came from the S550. I had a 2015 GT, then a 2019 GT before my 4xe Sahara.

In auto your front axle will be engaged and cost you some efficiency.

I have a similar system on the ram, and leave it in 2wd unless 4 is needed.

 

[Echo4papa]

In auto your front axle will be engaged and cost you some efficiency.

I have a similar system on the ram, and leave it in 2wd unless 4 is needed.

Yep, but that's what he's asking about... being able to use it on a solid surface in particular situations "cold potential black ice morning in the winter" which I guess is a think in NJ. For me, I walked my wife through putting it in 4HI Auto and back to 2HI while I was out of town because Elsa was rolling through and she had to take a family member to the airport through some potentially nasty weather. Of course, I get home a few days later and it's still in 4HI Auto, but I kind of expected that I suppose.

 

[GATORB8]

Yep, but that's what he's asking about... being able to use it on a solid surface in particular situations "cold potential black ice morning in the winter" which I guess is a think in NJ. For me, I walked my wife through putting it in 4HI Auto and back to 2HI while I was out of town because Elsa was rolling through and she had to take a family member to the airport through some potentially nasty weather. Of course, I get home a few days later and it's still in 4HI Auto, but I kind of expected that I suppose.

Oops, somehow skipped right over that when I read it this morning.
I spent ten years in Chicago, and black ice is a bitch, but it’s important to remember that 4wd only helps it go and not stop. I would run 4wd when there was enough snow on the ground that it would help track straight on the interstate or if I was having loss of traction from stops in 2wd. Would be fine to drop it in auto when it’s snowing, but remember it will shift the t-case in and out of 4. I always like knowing I was actually in 4 so I could drive accordingly.

Best advice is probably to find an empty parking lot and play with it (away from light poles) so you can get a sense of the differences in how 4 effects steering. Always best to be careful, the front wheels can still loose traction and slide, eliminating your ability to steer, especially since you can break them loose with power.

 

[Terminex]

“Normal” wrangler transfer cases have three modes: 2H, 4H, 4L.

Selec trac (as well as the optional version of the Rock trac on the new rubicons) adds a fourth mode: 4A
What you heard is true in regards to 4H & 4L, they should only be used on loose surfaces. (I.e. off road, thick snow, solid ice, etc….). Meaning do not use them on the road.

the 4A option can be used any time, as it defaults to rear wheel drive, and only sends power to the front wheels when needed.

i had selec trac on my 2019 JL, and have the new Rock trac with the 4A on my new Rubicon.

i have friends and family visiting me all the time borrowing my vehicles, and most of them have never driven anything but FWD or AWD. With weather conditions, i didnt want to have to worry about them, so 4A is the perfect choice for those occasions.

Since my new Rubicon is a 4xe, the reason I use 4A all the time is to get all the power. The power is limited in lower gears at full throttle in 2H.

 

[GATORB8]

“Normal” wrangler transfer cases have three modes: 2H, 4H, 4L.

Selec trac (as well as the optional version of the Rock trac on the new rubicons) adds a fourth mode: 4A
What you heard is true in regards to 4H & 4L, they should only be used on loose surfaces. (I.e. off road, thick snow, solid ice, etc….). Meaning do not use them on the road.

the 4A option can be used any time, as it defaults to rear wheel drive, and only sends power to the front wheels when needed.

i had selec trac on my 2019 JL, and have the new Rock trac with the 4A on my new Rubicon.

i have friends and family visiting me all the time borrowing my vehicles, and most of them have never driven anything but FWD or AWD. With weather conditions, i didnt want to have to worry about them, so 4A is the perfect choice for those occasions.

Since my new Rubicon is a 4xe, the reason I use 4A all the time is to get all the power. The power is limited in lower gears at full throttle in 2H.

Do you happen to have the link that breaks down the 4xe torque limiting by mode? Was trying to find it again the other day. \threadjack

 

[Echo4papa]

Do you happen to have the link that breaks down the 4xe torque limiting by mode? Was trying to find it again the other day. \threadjack

I wouldn't mind seeing that either. I've seen it mentioned but never confirmed. I've also seen it stated that you need to be in 4HI Auto because the rear will lose traction which would suggest that it might not be limited. Would definitely like to see some definitive info.

 

[Zombienation]

Appreciate the info everyone! This is a good thread for new people.

 

[Terminex]

Do you happen to have the link that breaks down the 4xe torque limiting by mode? Was trying to find it again the other day. \threadjack

sorry, no. I wasn't even aware of it until I got my 4xe last week. was running around in 2WD (you know, normal Jeep mode

I noticed that acceleration was disappointing off the line, but awesome when merging.

I put it in 4A merely because I was on a hill at a light, and needed to get accelerate quickly to be able to move over a lane. I took off, and it was a big surprise, as it had all of the acceleration I was originally expecting.

Then I noticed threads where other mentioned the same thing.

 

[Jocko]

Hmm I need to play around with this a bit more. I tried the whole 4A thing and the acceleration felt just as disappointing as usual. I should try it a bit more to be sure though...

 

[Terminex]

Hmm I need to play around with this a bit more. I tried the whole 4A thing and the acceleration felt just as disappointing as usual. I should try it a bit more to be sure though...

If you want the best acceleration from a stoplight:

4A
E-save
Battery charge (in the uconnect hybrid menu)

this will keep the engine running so you do not have 5e dely of it needing to start up.

 

[Jocko]

If you want the best acceleration from a stoplight:

4A
E-save
Battery charge (in the uconnect hybrid menu)

this will keep the engine running so you do not have 5e dely of it needing to start up.

Hmm yeah that's what I tried. I'll spend a little more time with it, though. It would be cool to be able to have more impressive acceleration as a party trick. I have actually become less worried about it though because of how impressed I am with the electric-only driving experience.

 

[Echo4papa]

If you want the best acceleration from a stoplight:

4A
E-save
Battery charge (in the uconnect hybrid menu)

this will keep the engine running so you do not have 5e dely of it needing to start up.

I don't even think you need to worry about all of that. Once the ICE comes on, it will stay on for a short while before shutting back off, so if you're in 4A and Hybrid mode at a light, just reach down and put it into manual shifting mode and the ICE should come on. Push it back over to D and you should be all set. If it's a long light, just wait a bit before putting it back into drive.

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