On Demand vs Full Time Auto 4x4 - what difference ?

[MacHudson]

Noob here.

Can someone explain the difference between the part time and full time 4x4 systems?

I did not notice any price difference on the Black Diamond when I was messing with B&P.

Without lockers, on the part time I don’t understand how you get traction to the axle wheel that’s got grip if the other one is slipping.

With full time, is this just a stronger Subaru? Why not just make it full time and do away with the part time option?

Sorry, it’s just not making sense to me.

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[Dlerojo]

Part time 4wd is the more traditional system and should only be used in icy/snowy or offroad conditions. Auto is higher end, usually a more expensive option, and more simulates AWD.

You are correct, without lockers power goes to the wheel with the least amount of traction. Example: Your left rear wheel has zero traction but your right rear does. The left rear will spin and your right will do nothing. A rear locker will force both wheels to spin regardless of traction

 

[frinesi2]

In Jeeps, at least, Part-Time means you can use it PART OF THE TIME, because the center differential is locked, which means you need to be on a slippery surface or you could damage your driveline. All-Time means you can use it ALL OF THE TIME - i.e. all three differentials are unlocked so you can drive in 4WD on high-traction surfaces.

On-demand usually means AWD (all wheel drive) which means it's in two wheel drive until it detects slippage and engages the front axle (in the case of the Bronco's rear-wheel-drive biased system).

Without lockers, then you won't get grip if one wheel is completely free to spin unless you have some kind of limited-slip or torque-biasing differential, or a brake-based traction control system.

 

[jtzako]

The "Auto" mode of 4wd on the Bronco is basically simulating what AWD cars have (front is engaged if slip is detected). The regular 4hi/4lo selectors lock it into 4WD mode. You'd probably leave it in "Auto" for most driving but select the appropriate 4wd mode when on a trail.

 

[MacHudson]

In Jeeps, at least, Part-Time means you can use it PART OF THE TIME, because the center differential is locked, which means you need to be on a slippery surface or you could damage your driveline. All-Time means you can use it ALL OF THE TIME - i.e. all three differentials are unlocked so you can drive in 4WD on high-traction surfaces.

On-demand usually means AWD (all wheel drive) which means it's in two wheel drive until it detects slippage and engages the front axle (in the case of the Bronco's rear-wheel-drive biased system).

Without lockers, then you won't get grip if one wheel is completely free to spin unless you have some kind of limited-slip or torque-biasing differential, or a brake-based traction control system.

You sound like the right person to ask!

Then the next question, and it’s apparently very important (and I should have done my homework in the past year or so...) do Broncos with the auto full time system have differentials or traction systems in order to compensate for the problem of a wheel that lacks traction?

 

[BroncoActual]

You sound like the right person to ask!

Then the next question, and it’s apparently very important (and I should have done my homework in the past year or so...) do Broncos with the auto full time system have differentials or traction systems in order to compensate for the problem of a wheel that lacks traction?

All vehicles have differentials. These videos are great explanations of what/how they work:




Broncos come with 4x4 part-time selectable (which would be like manually changing to 4H or 4L) and 4x4 automatic on-demand (which would be 4A). You're thinking of locking differentials, which you don't see until BL+. The GOAT modes will determine which 4x mode you're in as well as alter the "strictness" of the traction control. You can read about more about those modes in my other post that I took off of the Raptor forums.

 

[frinesi2]

You sound like the right person to ask!

Then the next question, and it’s apparently very important (and I should have done my homework in the past year or so...) do Broncos with the auto full time system have differentials or traction systems in order to compensate for the problem of a wheel that lacks traction?

The Bronco has an open front diff, optional locking rear diff, and I BELIEVE the center diff has an electronically actuated clutch pack that can vary the slip rate along with a true mechanical lock. It will also use the brakes for traction control (see - "turn assist" mode where it can pivot around a rear wheel ... this trick can only be done with fully open diffs and individual brake control, afaik)

But verification of the exact layout has been hard to come but, so I'm still fuzzy on the specifics.

Also, from @BroncoActual 's linked writeup (which is for the F-150, keep in mind) it sounds like Ford's differentiation between part-time and all-time is a little more abstracted from Jeep's (or, at least, my Jeep, which has 2H, 4H All-Time, 4H Part-Time, and 4L)

2H and 4H All-Time are both covered under the 4A setting.

4H Part-Time, on Ford, is just 4H.

4L is the same

(by the way, 4L is part-time 4WD with the transfer case in low-range, which gives you more torque and lower wheels speeds, which is better for more technical situations).


Anyway, to answer your question fully, I guess it depends on the drive mode you're in, but yes, the Bronco will be able to handle lack of traction at a single wheel (probably).

 

[MacHudson]

Thank you all for the explanations. I’m originally from snow country and have always wished for AWD. I will definitely continue to do my homework regarding snow and ice, and how the Bronco transmission is designed to handle that.

 

[KAQ]

Noob here.

Can someone explain the difference between the part time and full time 4x4 systems?

I did not notice any price difference on the Black Diamond when I was messing with B&P.

Without lockers, on the part time I don’t understand how you get traction to the axle wheel that’s got grip if the other one is slipping.

With full time, is this just a stronger Subaru? Why not just make it full time and do away with the part time option?

Sorry, it’s just not making sense to me.

I was just looking at the same thing, if you add the Automatic 4x4 it adds the locking rear diff option but there is no charge. I'm guessing this is a glitch. if not it's a no brainer to go with the Automatic.

 

[Dillhole]

I didn't expect that to be included in the Sasquatch package. I've never owned a 4wd with any full time or auto settings. Does it still have a 2-HI mode? Just asking for when I feel the need to lay down some juicy 11's.

Of course in the winter leaving it in Auto would be great. Kind of a pain with my JK if I'm stopped at a intersection and it's uphill or icy and I need to first notice I'm just spinning my rear wheels to reach down and pull back on the fun lever to get my ass moving. But then need to put it back into 2HI once I regain traction as to not bind the system.

 

[JesseS]

When I did my BD build (2.7/Auto) there was a $795 difference between Part Time 4X4 and the Advanced Auto TC. The reason I was looking close is I need to flat tow and it looks like only the Part-time can do that, which SUCKS!!

 

[LMB]

When I did my BD build (2.7/Auto) there was a $795 difference between Part Time 4X4 and the Advanced Auto TC. The reason I was looking close is I need to flat tow and it looks like only the Part-time can do that, which SUCKS!!

 

[RLW]

When I did my BD build (2.7/Auto) there was a $795 difference between Part Time 4X4 and the Advanced Auto TC. The reason I was looking close is I need to flat tow and it looks like only the Part-time can do that, which SUCKS!!

I’m not sure that is correct about the flat tow.
I think it can be done with both 4x4 systems as long as it is appropriately set prior to towing.
I would love a clarification on this from a ford person that actually knows.

 

[dgorsett]

I didn't expect that to be included in the Sasquatch package. I've never owned a 4wd with any full time or auto settings. Does it still have a 2-HI mode? Just asking for when I feel the need to lay down some juicy 11's.

Of course in the winter leaving it in Auto would be great. Kind of a pain with my JK if I'm stopped at a intersection and it's uphill or icy and I need to first notice I'm just spinning my rear wheels to reach down and pull back on the fun lever to get my ass moving. But then need to put it back into 2HI once I regain traction as to not bind the system.

I was surprised and pleased it was included in the Sasquatch also.

It will have a 2H, 4H (transfer case locked), 4L (Low range Transfer case locked) and 4A (Transfer case senses slip and locks when needed). Most of the time leave it in 2H (best MPG, least wear and tear) on intermittently slick roads or maybe high speed off roads use 4A, consistently slick roads or low traction smooth off road use 4H and for slow speed, steep or rough obstacle off road use 4L

 

[Rick Astley]

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