How AWD works (Includes Ford's 4A system)

[blanchardsbronco]

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[Tacanta14]

Well, I just read the whole thread, and STILL have no idea if the advanced 4WD is worth the extra cost. I have a 2021 Trail Boss with automatic 4WD, and living in the desert, 6.5 miles down a sand/dirt road, I keep it on, except on the highway (unless it's snowing, then it's either on or I'm in 4H), and have a 2022 BD on order, and didn't get the advanced, but might go for it. Any thoughts, anybody?

 

[stuckinohio]

I would add it for sure. You can't add it later and it will help resale if no other reason. I wish the Bronco I scored had it.

 

[CrystalRedTintCoat]

I want to throw in a silly anecdote that I've told before. 30 years ago (yow, that long? Now my head hurts), my family had a red over red 1991 2-door Explorer Sport. 4.0L, 5-speed, the first push-button 4WD vehicle my parents had owned. Dad was/is a big advocate of hubs that have to be locked in. Anyway, one winter, my mom wiped it out driving to work in the snow, hit a tree with the right side. Dad asked "where you in 4WD?" "No". "why not?" "I didn't want to use it all up".

Teasing Mom about it aside, it underscores the point someone else made in that most people have no idea how these things work. So it became very important to develop AWD systems that just work on their own without driver input. That's probably not in question, but it is exactly why the 4A option exists. The '91 was replaced with a black '98 Explorer Sport, this one with an automatic trans because that was paired with Ford's then cutting-edge "Control-Trac" system. The first 4A t-case used in midsized Ford SUVs. So, there's nothing truly novel or scary about 4A, it is just an ever-refined version of what's been around for decades.

I grew up with the full sized chevy blazer K5 in the 70s. If you wanted 4WD, you stopped the vehicle, put it into 4W mode, got out and turn the hubs on the wheels, and got back in. Your push-button 4WD is akin to this. But I’m not convinced the new Bronco’s 4A button is akin to not having to press the 4WD button / getting out and turning the hubs.

What’s STILL missing for me in 2022 reading this 2021 thread is whether it’s safe to use 4A on the pavement, in the rain, for example.

If you’re saying: “turning the hubs manually“ = “pushing the 4WD button manually“ = “4A in the bronco”,, then I’m royally confused and would NEVER use 4A on-road w/o snow.

But, if you’re saying: “turning the hubs manually” “Pushing the 4WD button manually” =“4H in the bronco”, then I’m in sync.

 

[bloominguez]

What’s STILL missing for me in 2022 reading this 2021 thread is whether it’s safe to use 4A on the pavement, in the rain, for example.

It may be missing in this thread, perhaps, but it's been covered in numerous other threads, the vehicle manual, and Ford's website. It's not a secret.

Of course it's safe to use 4A on pavement, in the rain or when it's dry. That's the point of 4A.

 

[CrystalRedTintCoat]

It may be missing in this thread, perhaps, but it's been covered in numerous other threads, the vehicle manual, and Ford's website. It's not a secret.

Of course it's safe to use 4A on pavement, in the rain or when it's dry. That's the point of 4A.

Thanks. I read some F-150 forums on “4A” which said “no faster than 15 MPH” which, frankly, seems like a typo and should have said “4H”. Right?

From the massive JalopNick article reference here, which is a great read, it seems that the Bronco’s 4A is “On-Demand Active AWD — Transfer Case-Based“; is that right?

Who manufacturers the Bronco’s “4A” transfer case — BorgWarner?

 

[bloominguez]

Thanks. I read some F-150 forums on “4A” which said “no faster than 15 MPH” which, frankly, seems like a typo and should have said “4H”. Right?

From the massive JalopNick article reference here, which is a great read, it seems that the Bronco’s 4A is “On-Demand Active AWD — Transfer Case-Based“; is that right?

Who manufacturers the Bronco’s “4A” transfer case — BorgWarner?

Sounds like misinformation (to use the trendy terms) is everywhere. Why in the world would you not be able to use 4A above 15 mph? The Bronco engages 4A (if available on that Bronco) when Sport Mode is selected!

Yes, I believe 4A is active, on-demand. Clutch based, controlled by the computers.

 

[bloominguez]

Thanks. I read some F-150 forums on “4A” which said “no faster than 15 MPH” which, frankly, seems like a typo and should have said “4H”. Right?

From the massive JalopNick article reference here, which is a great read, it seems that the Bronco’s 4A is “On-Demand Active AWD — Transfer Case-Based“; is that right?

Who manufacturers the Bronco’s “4A” transfer case — BorgWarner?

I apologize for being such a crusader on this topic, I guess I'm a big fan of 4A. And I feel like people really don't understand the differences between 4H (and 4L) and 4A. I grew up with the manual locking hubs then learned the differences when CRVs and RAV4s and others started coming with "AWD" (basically 4A). I think more people should order the Advanced Transfer Case (with 4A) given their use cases (not doing hard core off-roading).

I realize 4A is not needed, and maybe not wanted, if you're doing off-roading (why abuse a clutch-based transfer case?). But it's so nice to have 4A when you're on the street, and never worry about drive train binding. I tell my daughters: If the weather is sketchy, just select 4A.

I dug up some of my previous posts on this:
https://www.bronco6g.com/forum/threads/do-you-mostly-drive-in-2h-or-4h.55010/post-1611174

https://www.bronco6g.com/forum/threads/do-you-mostly-drive-in-2h-or-4h.55010/post-1611321

 

[CrystalRedTintCoat]

Sounds like misinformation (to use the trendy terms) is everywhere. Why in the world would you not be able to use 4A above 15 mph? The Bronco engages 4A (if available on that Bronco) when Sport Mode is selected!

Yes, I believe 4A is active, on-demand. Clutch based, controlled by the computers.

Not to belabor this thread and the point of 4A and all the other thread herein and on other sites …

Bronco Manual
Advanced 4x4 With Automatic On Demand Engagement (If Equipped)
This system monitors various vehicle sensory inputs to provide an increased level of performance. This system offers the driver two-wheel drive high, four-wheel drive auto, four-wheel drive high, and four-wheel drive low as available modes of operation. When you select four-wheel drive auto, the system continuously varies power to the front wheels for optimum performance for all on-road conditions. When you select either four-wheel drive high or four-wheel drive low, the system provides electronically locked power to the front and rear wheels for use in off-road or slippery conditions such as deep snow, sand or mud. Selecting four-wheel drive low also provides additional gearing for increased torque multiplication for conditions like deep sand, steep slopes, or pulling heavy objects.

SLIPPERY - ADVANCED 4X4 WITH 4A MODE, EXCLUDING: RAPTOR
For less than ideal road conditions, this mode can be used for crossing terrain where a firm surface is covered with loose or slippery material, such as snow or ice. Slippery mode lowers throttle response and optimizes shifting for slippery surfaces.

Four-wheel drive auto (4A) is the default four-wheel drive mode. Two-wheel drive high (2H) is not selectable in slippery mode.

—
So, to my mind, reading this Jalopnik article, this thread/forum, the owner’s manual it would seem that 4A is the Bronco replacement (I’m NOT saying equivalent) for what Joe Public calls “all time AWD”, not withstanding the Jalopnik article’s first paragraph that AWD is THE term for all things AWD/4WD and, not withstanding the fact that 4A is NOT “all time AWD”.

However, I find the Slippery GOAT mode misleading. The default AWD setting is “4A” for “surfaces covered with loose or slippery material, such as snow or ice.” Ford expressly does NOT say rain. Perhaps this is a documentation error. Perhaps it is intentional. I just now when I saw Slippery for the first time I thought rain too. And when I think about an on-demand, clutch based, computer controlled part-time AWD system, I figure 4A was safe for rain in addition to snow and ice …

I drive my Bronco in 2H all-the-time on pavement. But right now, here In NorCal, this “Dragon Storm” (literally the name for it) and our crappy city / state draining on the side roads and freeways, there‘s lots of puddling and water build up. So, I’ve been driving in 4A this week for added protection. I watch the power distribution “gauge” on the IP and can see that power is cut from the front-wheels once you get to “cruising” speed.

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