4x4 Part Time Selectable Engagement vs Advanced On Demand Auto Engagement

[BuckeyeinNV]

My sense is you just hit 4A when the weather is bad and don't worry about it. Seems like a nice feature to me.

4A is supposed to be for on-road but there is a chart floating around somewhere that says what each GOAT mode does and some off road modes engage 4A if you have it. If I find the chart I'll edit this post.

EDIT: So just sand mode...

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[Lcubed]

My sense is you just hit 4A when the weather is bad and don't worry about it. Seems like a nice feature to me.

4A is supposed to be for on-road but there is a chart floating around somewhere that says what each GOAT mode does and some off road modes engage 4A if you have it. If I find the chart I'll edit this post.

EDIT: So just sand mode...

at the moment, that chart is pure speculation and guesswork

 

[Laminar]

at the moment, that chart is pure speculation and guesswork

Yeah I wish people would stop pulling all of these charts and spreadsheets and pricing models from their ass and posting here with a tiny disclaimer, only to have people repeat and repost bad info.

4A is great for inclement weather, especially snowy areas. The system can do whatever the ECU tells it to do, so there's nothing that says it's a reactive system that only engages after slip is detected.

 

[King Luis]

Yeah I wish people would stop pulling all of these charts and spreadsheets and pricing models from their ass and posting here with a tiny disclaimer, only to have people repeat and repost bad info.

4A is great for inclement weather, especially snowy areas. The system can do whatever the ECU tells it to do, so there's nothing that says it's a reactive system that only engages after slip is detected.

what i'm wondering though is if it's cold/snowy conditions, why not just have it in 4H and not pay the ~$500 or whatever it is and use that money for accessories? again, depends on how ford packages it and prices it still.

 

[Lcubed]

what i'm wondering though is if it's cold/snowy conditions, why not just have it in 4H and not pay the ~$500 or whatever it is and use that money for accessories? again, depends on how ford packages it and prices it still.

if in 4H, and you encounter any 'dry' pavement and curves, you may end up winding up
the transfer case which is trying to keep the front and rear shafts spinning together like a spooler. if some slippage doesn't occur, something in the drivetrain will be stressed and
eventually break. 4A (or AWD) relieves those stresses by allowing the front and rear shafts to spin independently until lockup is actually required.

 

[ragingclue]

It'd be useful here in CO too for winter driving. I love AWD cars here for that time of year. (there's not usually enough uniform coverage of snow/slush on the road to use proper 4wd)

Yup that's what I've used 4A for in the ZR2 and it's worked great for that, as long as things aren't too hairy (in which case I should be in 4H anyway). It's pretty seamless when it engages too.

 

[King Luis]

if in 4H, and you encounter any 'dry' pavement and curves, you may end up winding up
the transfer case which is trying to keep the front and rear shafts spinning together like a spooler. if some slippage doesn't occur, something in the drivetrain will be stressed and
eventually break. 4A (or AWD) relieves those stresses by allowing the front and rear shafts to spin independently until lockup is actually required.

so is 4H more like a locker then? excuse my dumbness, still learning about 4wd and selectable 4wd, coming from a rwd sports car background with one diff and LSD.

 

[Lcubed]

so is 4H more like a locker then? excuse my dumbness, still learning about 4wd and selectable 4wd, coming from a rwd sports car background with one diff and LSD.

4H locks the center diff (if AWD). for part time applications, 4H locks the front and rear drive shafts together at the transfer case.

 

[King Luis]

4H locks the center diff (if AWD). for part time applications, 4H locks the front and rear drive shafts together at the transfer case.

oh. thats good to know. i didn't know it was an actual locker for the centre diff. thanks.

 

[Lcubed]

oh. thats good to know. i didn't know it was an actual locker for the centre diff. thanks.

i'm not sure if the bronco advanced transfer case actually implements a center diff or
even a variable clutch. it might be a bang-bang deal (all on or all off).

won't know until someone gets it into their grubby little hands.
(won't be me since i've got a super high reservation number)

 

[Laminar]

i'm not sure if the bronco advanced transfer case actually implements a center diff or
even a variable clutch. it might be a bang-bang deal (all on or all off).

Are there vehicles that still do this? The F150s with 4A are able to modulate power between axles. They'll default to 4 wheels from a stop and transfer to 2 at cruise to save gas. No reason to believe the Bronco would be any different.

 

[Lcubed]

Are there vehicles that still do this? The F150s with 4A are able to modulate power between axles. They'll default to 4 wheels from a stop and transfer to 2 at cruise to save gas. No reason to believe the Bronco would be any different.

i is an mechanical enjuneer,

spelling aside, we won't know until we get a good look
at the actual hardware. until then, it's all marketing

 

[Laminar]

i is an mechanical enjuneer,

spelling aside, we won't know until we get a good look
at the actual hardware. until then, it's all marketing

Is there a vehicle on the market today with a 4A-capable transfer case that simply bangs 4H on and off at will?

 

[Lcubed]

Is there a vehicle on the market today with a 4A-capable transfer case that simply bangs 4H on and off at will?

jeep wrangler sahara with select trek II.

see the description here:

https://en.wikipedia.org/wiki/Jeep_four-wheel-drive_systems

 

[dgorsett]

Any Ford Auto 4wd system I've driven sense wheel slip and engages seamlessly when required. The "slip" that triggers engagement is imperceptible to the driver and instantaneous. They seem to work flawlessly. I'm guessing they use what is termed a "sprage (sp?) clutch" which is an electro magnetic clutch that automatically locks when the two shafts spin at a different speed. This system is ideal when driving winter roads that have intermittent snowpack/ice. You can still manually lock 4H when conditions require.

edit: Laminar educated me later in this thread, I am in error about the sprag clutch, other than that I stand by the seamless engagement of 4A, that said I probably won't get it on my Bronco, I don't mind shifting from 2H to 4H as required. 4A is nice for bad weather commuting and travel in intermittent snowpack or ice.

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