4A acting like 4H, binding while turning on dry pavement

[Lil Red Broncette]

It’s perfectly fine for dry pavement, they make that very clear.

There’s broncos with 100k+ mileage that use 4A daily. Simply using it had nothing to do with your concern or failure.

Thanks. Some of the arguments remind me of something back with my original 88 Bronco II (and two others I later got). I would lock the hubs at the first threat of snow and leave them locked till after winter. This enabled me to switch from 2H to 4H on the fly at any speed. People would say why would you do that? The simple answer was because I didn't want to have to stop or get out in bad weather and it only cost me 1.5mpg (20.5mpg locked vs 22mpg). And while it did add wear, I would ask what is worse, leave the thing unlocked so that front axle and differential would just sit and never get warned up to drive out moisture? Or run it so it goes warm, moisture driving out, etc? Fact is I got 197K miles on that 88 B2, never had a problem with the front diff or axle.

My thought running 4A goes back to that, to give that stuff some more exercise than just under the specific conditions I need it.

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[Lil Red Broncette]

Thanks all for the comments. I appreciate it. I'll see what the shop says.

 

[BroncoChallenger]

If it is not for dry pavement, they should be clear it isn't. If not dry pavement, what is its use, wet roads? Cause anything worse than we 4H would be fine.

Equally, it seems doing aggressive things in sport mode would include on dry pavement.

If you'll note, I said in my opinion. My opinion is based on being a powertrain engineer with some years of experience, albeit not with the Advanctrac t-case.

My opinion still stands though - I can be plenty aggressive in our Bronco or my wife's Expedition (same t-case system) without using 4A. But then, I grew up driving high-horsepower RWD cars that could smoke the tires through 2nd gear and into 3rd while still suffering from body roll in the corners, so I'm pretty experienced at putting the power down with only (2) drive wheels instead of (4).

I'm not telling you not to do it. I am telling you in my opinion it's not necessary and is causing unnecessary wear. But that's all it is, my opinion.

 

[userdude]

If it is not for dry pavement, they should be clear it isn't. If not dry pavement, what is its use, wet roads? Cause anything worse than we 4H would be fine.

Equally, it seems doing aggressive things in sport mode would include on dry pavement.

I have 40k miles in 4a, I've not had an issue yet. I'm assuming I'll need a new clutch pack by 150k miles.

 

[DALOLA]

Opinions aside, why do some still insist 4A "is not meant for dry pavement", as if, some kind of fact?

Perception is not reality, but in your own head. OP clearly has some kind of malfunction. Causation not to be confused with correlation....

OP, let us know the outcome, good luck!

 

[Brian_B]

I

Opinions aside, why do some still insist 4A "is not meant for dry pavement", as if, some kind of fact?

Perception is not reality, but in your own head. OP clearly has some kind of malfunction. Causation not to be confused with correlation....

OP, let us know the outcome, good luck!

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[crenca]

I guess I'm confused by the responses....I'm just not understanding why the 4A mode is causing issues that have been around for 20+ years. Please help me understand. ELI5

Opinions aside, why do some still insist 4A "is not meant for dry pavement", as if, some kind of fact?Perception is not reality,....

My best guess is that because we are in the '4x4' world and on a '4x4' forum, folks are relying on their past history with traditional dog clutch transfer cases and the limits thereof. They assume (either consciously or unconsciously) that Ford's "4A" system is somehow an "automatic" version of a traditional transfer case, and thus they are reluctant to trust it.

That assumption is not correct - Bronco's with the advanced "4A" transfer cases are real-honest-to-goodness All Wheel Drive vehicles the same as Honda's, Subaru's, Audi's, etc. . You can put your Bronco in "4A" the day you drive it off the lot and leave it there for the next 200,000 miles (and baring any technical trouble) in all conditions and it will not "bind" or "cause premature wear", nor will it need unusual fluid change intervals, etc.

In other words it is by design and engineering a real AWD vehicle and carries no special caveats.

That said....I could be wrong about the underlying cause for these opinions. Maybe there are contingents of folks on Honda/Subaru/Audi forum's who believe those systems "cause premature wear" etc., and maybe there are even those who modify those vehicals such that they can run them in 2 wheel drive on dry pavement and such

 

[Thor_1]

My best guess is that because we are in the '4x4' world and on a '4x4' forum, folks are relying on their past history with traditional dog clutch transfer cases and the limits thereof. They assume (either consciously or unconsciously) that Ford's "4A" system is somehow an "automatic" version of a traditional transfer case, and thus they are reluctant to trust it.

That assumption is not correct - Bronco's with the advanced "4A" transfer cases are real-honest-to-goodness All Wheel Drive vehicles the same as Honda's, Subaru's, Audi's, etc. . You can put your Bronco in "4A" the day you drive it off the lot and leave it there for the next 200,000 miles (and baring any technical trouble) in all conditions and it will not "bind" or "cause premature wear", nor will it need unusual fluid change intervals, etc.

In other words it is by design and engineering a real AWD vehicle and carries no special caveats.

That said....I could be wrong about the underlying cause for these opinions. Maybe there are contingents of folks on Honda/Subaru/Audi forum's who believe those systems "cause premature wear" etc., and maybe there are even those who modify those vehicals such that they can run them in 2 wheel drive on dry pavement and such

I would not compare it to a true AWD system like Honda. They were built from the ground up as an AWD system.

For me, I view Ford’s AWD system as something you use when the road is wet or the snow/slush is intermittent, making 4H difficult to use. That’s how I will be using it.

Perhaps I am wrong. I just don’t see the need to have the Bronco in 4A going 75 mph.

 

[crenca]

I would not compare it to a true AWD system like Honda. They were built from the ground up as an AWD system.

So was Ford's "4A" system which predates the Bronco. 4A is a system, not just a transfer case. This includes computers (the heart of all modern AWD systems) which use a holistic algorithmic approach to control how/when/where torque gets distributed, etc. that puts power down in various conditions (i.e. speed, steering angle, gear selction, etc.).

You have a "feeling" about it, but why? What exactly leads to those feelings? I submit it is not based on an understanding of the engineering and execution of modern AWD systems in general or Ford's in particular.

Perhaps I am wrong. I just don’t see the need to have the Bronco in 4A going 75 mph.

What do you think Ford's 4A system is doing when you are driving at 75 mph? How would that be different/same if you had your Bronco in 2H? I know the answer(s), but do you - and how do your answers relate to your general unease of 4A as a whole?

 

[dgorsett]

Thanks. Some of the arguments remind me of something back with my original 88 Bronco II (and two others I later got). I would lock the hubs at the first threat of snow and leave them locked till after winter. This enabled me to switch from 2H to 4H on the fly at any speed. People would say why would you do that? The simple answer was because I didn't want to have to stop or get out in bad weather and it only cost me 1.5mpg (20.5mpg locked vs 22mpg). And while it did add wear, I would ask what is worse, leave the thing unlocked so that front axle and differential would just sit and never get warned up to drive out moisture? Or run it so it goes warm, moisture driving out, etc? Fact is I got 197K miles on that 88 B2, never had a problem with the front diff or axle.

My thought running 4A goes back to that, to give that stuff some more exercise than just under the specific conditions I need it.

You are one of the few that understand both the Bronco advanced system and the old manual hub system, bueno. A third system is the auto hub shift on the fly of the 80s and 90s. I would shift into $
4wd and back to 2wd in my driveway when expecting bad roads. This would engage the auto hubs for the remainder of the trip and make the shift on the fly smoother.

 

[CalvinT]

A third system is the auto hub shift on the fly of the 80s and 90s.

I hated those. They'd tend to automatically unlock in certain situations such if you had alternating steep up and down on the same road.

 

[dgorsett]

I hated those. They'd tend to automatically unlock in certain situations such if you had alternating steep up and down on the same road.

They worked fine for me just pre engaged like mentioned above, sounded kinda violent if I didn't pr engage. Had one blow out once, replaced with manuals.

 

[CalvinT]

They worked fine for me just pre engaged like mentioned above, sounded kinda violent if I didn't pr engage. Had one blow out once, replaced with manuals.

They'd unlock on me if I had just finished climbing a hill then descended, so at the top I'd have to backup to unlock them. Then relock them in reverse before going down the hill. If I didn't do that they'd unlock when going down the hill and I'd start sliding until they relocked with a bang.

The hill in question was a 40% grade and a bit loose. Once I was following a small cat (International crawler) up the road and his left track kept slipping. He'd have to stop, make an adjustment, then continue on.

I have a saying, "automatic features tend to screw up automatically."

 

[Valhalla]

If you'll note, I said in my opinion. My opinion is based on being a powertrain engineer with some years of experience, albeit not with the Advanctrac t-case.

My opinion still stands though - I can be plenty aggressive in our Bronco or my wife's Expedition (same t-case system) without using 4A. But then, I grew up driving high-horsepower RWD cars that could smoke the tires through 2nd gear and into 3rd while still suffering from body roll in the corners, so I'm pretty experienced at putting the power down with only (2) drive wheels instead of (4).

I'm not telling you not to do it. I am telling you in my opinion it's not necessary and is causing unnecessary wear. But that's all it is, my opinion.

Although I completely agree with you on need. It is fine in RWD. I do disagree on wear.

Here is why, all of there parts are turning anyway as there are no hub disconnects. One of our engineers said our awd works exactly the same as the 4a system on our offroad cars.

To the OP trip to the dealer, may already be done I have one more page to read.

 

[Valhalla]

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