Let’s settle this, what is it?

[chuck s]

If the '17 "off road" dash display is to be believed in 4A the torque is constantly varying between the front and rear axles with some always going forward. This at least implies there's a differential there. Controllable, but still a differential. No display on my '07 but I believe the "elf" waited for rear slippage before diverting power forward.

My Explorer didn't have 2H and was always in at least 4A.

I'm in 2H 99% of the time as I can feel the added drive train strain when I switch to 4A and it makes no sense to me to run this way.

Anyone who has driven with a locked transfer case on the road and experienced the *** Bang! *** release of axle wind-up will appreciate the differential.

-- Chuck

 

[JExpedition07]

It’s pretty cool how well this BorgWarner unit works in our ‘07-‘14s, it’s smart. I played around a bit with the rain. If I punched it in 2H of course the rear spins and then traction control kicks in. But in 4A with a punch of the gas pedal no slippage and it tracks straight as an arrow. How does it know it’s going to slip before it happens? You can’t trick it if you try.

 

[G213]

If the '17 "off road" dash display is to be believed in 4A the torque is constantly varying between the front and rear axles with some always going forward. This at least implies there's a differential there. Controllable, but still a differential.

There’s definitely torque going to the front, even without slippage. There’s a clear change in road noise (if you’re paying attention) and the steering becomes a little stiffer. So that means differential? Interesting...

So I’d probably be the kind of guy who’d also leave it in 4A all the time...except

A. The steering is stiffer in 4A, which I could live with.

But......

B. With no drain plug on the front differential, that sounds to me like FoMoCo isn’t expecting you to use the front differential all the time. (Maybe I’m wrong, maybe the front doesn’t do as much work as the rear differential and therefore doesn’t need to be changed?)

Also when in 4A, you get the yellow dash light, just as if you’re in 4H or 4L. 2H comes on for a couple seconds when selected then turns off. Maybe I’m overthinking it, but I have a feeling that’s some FoMoCo engineer saying “2H is for normal operation and 4A is for occasional use”

 

[jeff kushner]

its an electrically changed transfer case, the little motor shifts between ranges 2h, 4h 4 lo, 4auto and neutral in my case.
its got a chain and clutch packs, torque on demand system allows power to go to the front wheels if slippage is detected, or so it states at the b/w site

Yeah, I'd listen to the helicopter mechanic.....those guys will remain quiet before ever being wrong.......


FWIW; my '17 has been in 4A since the day it came home other than playing with it a little.
I don't know exactly how it works, nor do I really care. If 4A will provide the best choice for driving so that all the features I paid for are active, I'll use it all the time.

jeff

 

[Plati]

There’s definitely torque going to the front, even without slippage. There’s a clear change in road noise (if you’re paying attention) and the steering becomes a little stiffer. So that means differential? Interesting...

So I’d probably be the kind of guy who’d also leave it in 4A all the time...except

A. The steering is stiffer in 4A, which I could live with.

But......

B. With no drain plug on the front differential, that sounds to me like FoMoCo isn’t expecting you to use the front differential all the time. (Maybe I’m wrong, maybe the front doesn’t do as much work as the rear differential and therefore doesn’t need to be changed?)

Also when in 4A, you get the yellow dash light, just as if you’re in 4H or 4L. 2H comes on for a couple seconds when selected then turns off. Maybe I’m overthinking it, but I have a feeling that’s some FoMoCo engineer saying “2H is for normal operation and 4A is for occasional use”

I almost always (99%) drive in 4A. Have done this since my first Expy in '99. Do it with my 2014 & my 2003. Have never noticed anything other than better traction, which you don't notice that but you do notice wheel spin under certain conditions in 2WD. Never noticed any drive train strain. Don't care about losing a potential 1/2 mpg. Don't think parts wear is greater. Prefer safety and road grip. Don't really understand why people would run in 2WD unless you like to slide out in corners in winter or are hoping to get better gas mileage in your 6500 pound gas hog. IMHO

Opinions are like azzholes … everyone has one and they all stink.

 

[chuck s]

2H is the default, which is why I've run it the past 12 years on both trucks. I switch to 4A in the rain and other marginal weather.

Gonna set it to 4A and run for a while.

-- Chuck

 

[creef14]

For standard day-to-day dry weather pavement driving. 2H w/ trac control is going to serve you just as 4A. But you definitely get better gas mileage and you are less likely to run into wear related issues and maintenance on the front diff/transfer case/whatever we're calling it now, because you are putting less wear on it.

I only go to 4A when there is some kind of reason for it, like rain, gravel, light snow.

 

[JExpedition07]

I’m a hybrid of sorts I guess. Most of the time I leave it in 2H. In winter I leave in 4A since you never know what you’re going to get on the roads. According to the manual it’s ok to leave it in 4A.

 

[Tom Aldridge]

Don't know exactly what Ford is doing in software to transfer drive to front wheels under no-slip conditions in this application but the clutch type transfer cases have some amount of friction in the clutch packs so there will be some amount of drive if the front differential is engaged, or the axles engaged to the wheels (appears they did it that way with vacuum operated wheel end couplers in gen2 Expy).
Maybe the below doesn't apply directly to the Ford but is general info related to clutch type Transfer cases and I'd expect it to apply with the BorgWarner clutch type transfer case.

I have a bit of experience with the GM trucks using this configuration. When the drivetrain is put into Auto4WD, the front differential to axle is engaged so any drive coming through the front driveshaft from the transfer case will be applied to the axles. In that condition, the TCCM controls application of the transfer case clutches as needed. Control to the transfer case can be completely disabled (using Tech2) and there is still noticeable drive to the front wheels, due to friction of the clutch packs in the transfer case.
If fluid without the proper friction modifiers is used in the transfer case, this is more noticeable.
Fuel economy is increased with Auto4WD disabled because the front axles are freewheeling in relation to the front driveshaft and differential.

 

[JExpedition07]

I used 4A today in conditions I’d normally use 4H (low visibility thick snow), 4A reacts so fast it’s undetectable and you get no wheel-spin from a stop.