mechanicboy

Has anyone used their automatic 4wd system available on the Lariat and above? Is it the kind of system that is more like an AWD and it constantly turning the driveshaft when driving or does it wait for tire spin then engage the driveshaft and hubs?

Thanks.

Ssls6

On my 2012 the front hubs lock when I dash shift to 4A, the transfer box at 4H, the rear diff when I pull the button.

Kantuckid

iTrader: (1)

I asked my BIL a similar question over the holiday, as he delivered new Ford's from Louisville for his last career. HE said-"they(the super duty trucks) have an issue in the past with throttle sticks". To explain, he said he was asked by his boss how he "got out of the truck" that had landed him off his carrier/on the ground, in a rather spectacular way, after the auto 4WD throttle had stuck, while in 4WD auto.
I opened the door he said, as I was on the ground by then! Seems he had started the truck and it flew off the carrier unexpectedly!

As previous questions about this feature-recently too- from me & others , owners say MPG suffers a tad, so something is turning in 4wd-auto.

StonedGreen

I have tried it as I took delivery during a snow storm. I heard the hubs locking and it has been pretty seamless. Although people say that 4A is a set it and forget it, I don't agree. I take it off when it's dry as I don't need the hubs to turn for nothing

68ss396

Unless Ford made changes on the 2015 F150 you don't have hubs. You have CV (constant velocity) joints. They turn all the time. You have a differential in the front just like in the rear. The front driveshaft spins all the time as well. This is how you achieve the shift on the fly. Does not matter if you are in 2wd, 4A,4H, or 4L. Everything in the front turns when the truck is moving. Unless they have some actuator that disengage's the front driveshaft. Which I don't think they do. But I could be wrong. The only new truck that I know of that still has hubs in the front are the super duty's. They have the manual lock outs on them. If locked out or "free" the front drive shaft does not spin because the inner shafts in the axle are not turning. If "locked" it does. The super duty has a live axle in the front. The F150 does not.

brulaz

It uses a clutch-pack differential by Borg-Warner. They claim they can predict wheel slippage, and I've heard it works pretty well. There was another discussion about this here just a few weeks ago. Search might find it.

As for which parts of the drive train are engaged when, I too would like to know. Seems to be some contradictory info here.

StonedGreen

The front drive shaft does not spin all the time. It's been like that since 2004 as the front hubs are controlled by vaccume engaged hub with a rubber diaphram. Yes there are CV joints, but the only spin when 4x4 is on

mechanicboy

What? I'm not sure what all you're saying here because your grammar/wording isn't right. What does the auto 4wd and throttle sticking have to do with each other? Sounds like your friend put the truck in gear and left the vehicle because regardless of if it was in 4wd or not the vehicle isn't under power unless the transmission is in gear. I was the head mechanic for a trucking company a while back and heard all kinds of stories that usually were lies the truckers made to try and save their asses.

Ok, makes sense.

What this guy said: I have a 12' and this is the way mine works.

This is the real information I want. So from what I gather when in A4 the front hubs lock, when slip is detected (or predicted?) the clutches are engaged in the transfer case causing an instant transfer of power to the front driveshaft. This works very similar to my dads silverado. If it is then changing the fluid often would be suggested as there's clutch material in the oil but no filtration system on the GM unit which contributes to premature wear.

68ss396

I stand corrected. I just went and looked. The front drive shaft does not spin and neither do the CV joints. Learn something new everyday. Thanks!

68ss396

I stand corrected. I just went out and looked. The front drive shaft does not spin and the CV joints don't either when i 2wdI learned something new. Thanks!