So 4A is not what I had thought...

[KABQ]

This system has been in F150s for at least a decade and they aren't grenading transfer cases left and right. Just sayin'.

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[Docindahouze]

This system has been in F150s for at least a decade and they aren't grenading transfer cases left and right. Just sayin'.

I have 4A in my 2016 f150. I keep in 4A. I bought it new and now has 136,000 miles no issues.

 

[Bronco cat]

All the system in the bronco has been around for DECADES at ford. My light 90’s early 2000 expedition had the exact same transfer case……… it’s a system with proven longevity.

 

[the poacher]

Over the last couple years there has been several discussions about 4A, along with all the "rules" about using 4x4 in high traction environments (like the street).

I've even contributed to multiple threats about 4A where the thought process was that it's in two-wheel drive unless it's senses slippage and then it kicks into 4 wheel drive.

This is not the case and Ford has seemed to have reinvented physics

All of us that have SPORT mode know that 4A engages with this GOAT and it is specifically designed for the street. Now that goes against the "No 4x4 on street" rule. However with the mentality that the 4A/4H doesn't kick in until it needs to, it should not be an issue.

Well I've been playing around with 4A and watching the "power distribution" and a bunch of us, including myself, we're wrong with our assumptions.

4A basically has the vehicle in 4x4 mode pretty much the entire time. There are some inconsistencies, but the only time that I've seen it NOT applying power to all wheels is when off the throttle, or I think, if you have the steering significantly turned BEFORE applying throttle.

To give you some examples, going 75 mph down the freeway and giving it some throttle = 4 wheel drive

Throttling while going through twisty turns on a mountain road = 4 wheel drive.

To me the scariest.... Doing a U-turn at a light (which requires throttle) = 4 wheel drive.

Like I said, there have been a couple of situations when I was testing, and if I turn the steering wheel significantly Before applying the throttle, it seems = 2 wheel drive.

I don't get me wrong, I love the feel of basically AWD... It's been storming (rain) all week where I live, and in 4A, the Bronco has been planted and not a single wheel slip.

I just hope Ford design this correctly and taking windy roads in sports mode isn't going to break something.

Hey da_jokker, I have a BL and so do not have sport mode. If I put my goat into Slippery mode, it goes into 4a. After driving the past 10 days and over 500 miles in continuously snowy, and icy conditions, I can say that it is a great all round mode for exactly that, slippery road conditions.

 

[Lil Red Broncette]

This doesn't surprise me, but I am wondering why it is delivering power to all wheels is a concern because it shouldn't.

The descriptions that 4A was just a means to automatically engage 4H when there was wheel slip never made sense. It is al all wheel drive system (AWD).

I think it all gets messed up by Ford and others trying to differentiate AWD from 4WD to lay people who really don't understand why conventional 4WD systems can't be run on dry pavement. So they use analogies they consider good enough for the lay person that are technically inaccurate.

So there are oversimplifications like the "its like 2WD but all 4WD when you need it" or oversophistications (like that word I made up) that describe it as some magic system that detects slip at a wheel and directs power to it.

Then people who know how cars work try and take that language literally.

If you don't know what a differential does between your drive shaft and wheel axles to allow the wheels to turn at different rates stop here.

If you know what a differential is, you probably know that 4WD is no bueno on dry pavement because the basic transfer case does not allow front and rear drive shafts to turn at different speeds. So it binds up when turning because front and rear axles need to be at different speeds just like the right side wheels are going to be different than left side wheels. That trying to turn on dry pavement would be much like trying to do so with locker engaged at the differential.

So to change 4WD to an AWD system it just needs to allow the two drive shafts to rotate at different speeds. I am not sure how most do this. One method would be the equivalent of a differential at the transfer case. Down side would be one wheel slipping in 4A could result in getting stuck unless that diff in the transfer case was limited slip.

In what I described above going between 4A to 4H would be the equivalent of locking that differential in the transfer case.

I don't know that is how it is done. One could make a system where all power goes to the lower speed drive shaft while the faster "free wheels" sort of like a bicycle wheel when you don't pedal. In any case going from 4A to 4H just goes from allowing the drive shafts run at different speeds to them being locked to the same speed.

 

[JohnnyBronco]

Over the last couple years there has been several discussions about 4A, along with all the "rules" about using 4x4 in high traction environments (like the street).

I've even contributed to multiple threats about 4A where the thought process was that it's in two-wheel drive unless it's senses slippage and then it kicks into 4 wheel drive.

This is not the case and Ford has seemed to have reinvented physics

All of us that have SPORT mode know that 4A engages with this GOAT and it is specifically designed for the street. Now that goes against the "No 4x4 on street" rule. However with the mentality that the 4A/4H doesn't kick in until it needs to, it should not be an issue.

Well I've been playing around with 4A and watching the "power distribution" and a bunch of us, including myself, we're wrong with our assumptions.

4A basically has the vehicle in 4x4 mode pretty much the entire time. There are some inconsistencies, but the only time that I've seen it NOT applying power to all wheels is when off the throttle, or I think, if you have the steering significantly turned BEFORE applying throttle.

To give you some examples, going 75 mph down the freeway and giving it some throttle = 4 wheel drive

Throttling while going through twisty turns on a mountain road = 4 wheel drive.

To me the scariest.... Doing a U-turn at a light (which requires throttle) = 4 wheel drive.

Like I said, there have been a couple of situations when I was testing, and if I turn the steering wheel significantly Before applying the throttle, it seems = 2 wheel drive.

I don't get me wrong, I love the feel of basically AWD... It's been storming (rain) all week where I live, and in 4A, the Bronco has been planted and not a single wheel slip.

I just hope Ford design this correctly and taking windy roads in sports mode isn't going to break something.

You are misreading the displays for sure. 4A is in fact just like any other all wheel drive vehicle like my X4 rear wheel drive always and only engages front when slippage occurs. These are not intelligent like Subaru or Honda.

 

[JohnnyBronco]

Not really....in the 80s most used an actual differential in the transfer case ....with no computers controlling anything. These days there is a electromagnetic wet clutch pack, it is activated by an electromagnet which has various degrees of pressure available. This system uses a set of ball bearings in a truncated slots. The slots the balls roll in are tapered, so the further they roll up the ramp the more pressure is applied to the clutch pack. I've posted pictures of the internals already on other threads. This is controlled and activated by the computers. Also the system uses pulse width modulation at 12v input, NOT a solid 12v on/off type switch. This allows the system to apply pressure to the clutches in various degrees seamlessly. It can make hundreds of adjustments per SECOND...One of the best systems available.

Those were not AWD but 4WD. But as a caveat my Cherokees supplied power Continuously through the mid mpqunt tqranasfer case and the shifting into getting power to front axle was an electric solenoid shifting a gear inside the axle. The full time power to the transfer case maodel was what starting in the 70s allowed shifting I to 4wd at speed and not a crawl

 

[Oldhippie]

Not really....in the 80s most used an actual differential in the transfer case ....with no computers controlling anything. These days there is a electromagnetic wet clutch pack, it is activated by an electromagnet which has various degrees of pressure available. This system uses a set of ball bearings in a truncated slots. The slots the balls roll in are tapered, so the further they roll up the ramp the more pressure is applied to the clutch pack. I've posted pictures of the internals already on other threads. This is controlled and activated by the computers. Also the system uses pulse width modulation at 12v input, NOT a solid 12v on/off type switch. This allows the system to apply pressure to the clutches in various degrees seamlessly. It can make hundreds of adjustments per SECOND...One of the best systems available.

This my understanding also (4wd with available computer controlled “slip”). All the misleading/misinformation on all these posts is crazy!! I will say it is weird it unlocks the front in “coast”, kind’a like using the “hand brake” to spin in snow/ice??

 

[Boxer4]

Somewhat on topic- my understanding is that you can shift in and out of 2H to 4A on the fly.
Has anyone experienced problems regarding speed or road conditions ?

 

[GI_Jo_Nathan]

I will say it is weird it unlocks the front in “coast”, kind’a like using the “hand brake” to spin in snow/ice??

Sure, but that also means it's not going to lock up the steering wheels when not under power.

 

[NinjahGoose]

4A on the streets is nothing new. My 2012 Limited 4Runner is always in 4A and that tech is a lot older than 2012. The Lexus GX and LX have the same tech.

 

[HCGxKaLiBeR]

imo Bronco's Advanced 4X4 is a Part-Time AWD system with Low Range function.

Center differential torque split is actuated by its clutch packs.
Can be switch on and off on the fly on any condition.
Clutch can be locked to archive 50:50 torque split. (Not sure if it has a mechanical locker or simply pressed really hard to achieve the effect)

Center differential torque multiplier (mechanical gear reduction) can be actuated by Low Range mode.
Can only be switched on and off when the vehicle is stopped.

Personally I toggle 4A whenever I please. No issue at all.
I don't drive with it all the time as there has to be wear and tear on the clutch packs. As of how durable they are, no one knows.

 

[Snacktime]

Interesting read, big thing is programming. I don't think any of us know how aggressive Ford was with the programming. Lots of systems are reactive, detect slip and then transfer power. Bronco could have proactive programming that transfers power before slipping. Ford really did the programming right on Focus RS and could have applied a more aggressive programing to the broncos since it is an enthusiast vehicle.

We have had reports of transfer case clutch smells on new broncos, I wouldn't be surprised if sport mode 4a is more aggressive than regular 4a.

Lucky for me my bronco only has 4h.

 

[BlueBronco]

I have 4A in my 2016 f150. I keep in 4A. I bought it new and now has 136,000 miles no issues.

Samesies as my 14yo would say. 2016 F150 KR 138k miles and 4A since the day I bought it new.

 

[KosmicKid]

My Raptor stayed in 4a for over two years without issue. My bronco is getting the same.

^^This^^
I drove my Raptor in Sport mode/4A for 3.5 years and no issues. Bronco stays in Sport/4A and has been like that for since I got it over a year ago.
I've watched the PDM (as I did in the Bronco Sport we had for a bit) but have never had any concerns over when the front wheels get power.
I look at as if they (Ford) didn't want us to use it then they wouldn't have given it to us much less GOAT Modes that engage it with no caveats on it's usage.

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