Ford Auto Hubs can cause spectacular failure

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What you are describing can only happen if you have the truck in 4WD High. 2003 and beyond 4WD Expeditions with those types of hubs leave the front hubs engaged when you are in A4WD (automatic 4WD). Either you stupidly left your truck in 4WD while driving on the highway, or something else is broken. Just locking in the front hubs alone will not cause the sort of problem you are describing. You still have a front differential, and if the drive shaft from the transfer case is free-wheeling, there will be no binding - just slightly reduced gas mileage and extra wear on the front axles. 1999 to 2002 4WD Expeditions didn't even have disconnects on the front driveshafts. The front axles were always engaged.
You need to either realize you left the truck in 4WD on the highway, or have the real problem diagnosed.
Ed
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I thought this story sounded odd, and what you and Matt said makes perfect sense, and also explains why Ford wouldn't cover it!
Jeff DeWitt
Ed White wrote:

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Ed White wrote:

Why is a truck in 4x4 on the highway?
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Because the operator is a maroon (sic), or the 4WD system is broken. My vote is the former ...
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I see a lot of replies that are dropping the ball on this one.... SuperDuty ESOF is a lot different from anything I have seen discussed....
What is needed.... mileage on the truck when the failure occurred... and miles on the truck when the last spindle service was performed.... Many owners discount the importance of the large (and spendy) steering knuckle seals regarding proper 4WD operation.... The operation of the auto hubs is vastly misunderstood and, IIRC, I have posted on the subject before....
Having said that.... the failure you describe should have been accompanied by sufficient warning that something was amiss.... at the very least, there would have been a transient vibration.... Not necessarily a "distressing" vibration but it would have been something out of the "normal"....
Now...... if the truck will still move, modern logic tells us we can still drive it.... no matter how bad the concern - I'm not picking on you.... I'm talking about too large a percent of my customer base....
By your own admission, "This pickup has almost always seemed to bind in turns.". This is a sure sign that something is wrong. If, after your dealer said "nothing is wrong" and you felt that something WAS wrong... it is time for a second opinion....
Getting back to the hubs.... the hubs are not the weak point.... lack of proper service IS!!! Our shop is almost exclusively centered around SuperDuty 4X4s.... This system is virtually trouble free...... as long as proper maintenance is performed....
Your warning should be "perfgorm proper maintenacne"... not "this system sucks"..... After all... it worked great up until it didn't work any more , right?

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The vacuum operated hublocks on Super Dutys are prone to early failure, I would submit that most owners don't ever touch them so they wouldn't know if they work or not. On my '02 F250, I had two hubs locks (both from driver's side) replaced under warranty due to failure to properly engage/disengage. The first one happened at under 20,000 miles, the second under 30,000. After warranty expired, they failed again at 45,000 miles and I had them replaced with Warn manuals. My current Excursion has had no problems yet, however.

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I know the system is not the same as an F150, - however, I can't see where having the hubs engaged should cause binding if the transfer case is in the 2WD position.
Here is what I think I understand -
A 2000 SuperDuty offered two 4WD systems - a manual system and an electric shift system. The manual systme has manual locking hubs and requires the transfer case to be manually shifted to 4WD. As long as the transfer case is not in 4WD, there should be no binding even if the hubs are locked. The electric shift system electricaly engages the transfer case. The hubs can either be in an automatic mode or a manual mode. If you leave the hubs in the automatic mode, then they are controlled automatically (using vaccum). When you shift the switch on the dash to 4WD the hubs and transfer case are engaged. You can also manually lock the hubs. Either way, unless the transfer case is also shifted to 4WD, there should be no binding.
Do you agree?
Ed
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All true, Ed. The OP had his T case in 4wd, whether by ignorance or by truck malfunction. He may have thought it would be safer in the rain. I knew a woman who put her Jeep Cherokee in part time 4wd whenever it rained, she wondered why her front U joints broke...I told her she was lucky it was only that...

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The act of shifting in and out of 4wd definitely was engaging/disengaging the front transfer case. Every time I've spun back wheels on a slick boat ramp, shifting to 4wd pulls it right out. There's also 4wd roads I would have been able to drive in 2wd. Yet with the hubs set to "automatic", they still were binding in turns (although not as much as the few times I made turns in 4wd).
This is kind of what led me to believe a little binding in hard turns was normal. I could definitely see the difference between dialing 4wd and 2wd, and not really understanding at the time the way the hubs worked ...
Rob

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"Front transfer case?" How many transfer cases does your truck have?
I think you mean "front axle." The transfer case is what engages the front axle.

I think I found the problem.
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If, for some reason, the front hubs are locked in, sharp turns will cause the U-joints to bind as the axles rotate.... The single cardan U-joint has a very small range of "stable" motion (about 3 degrees deflection). If the joint is positioned so that it has a large deflection, a whipping motion can set in - the physics of this whipping motion are easy to understand... describing it, not so easy. Simply stated - the cup on the inside of the deflection travels less distance than the cup on the outside of the deflection.... the bug-a-boo being that they are both travelling at the same rpm...
Our shop deals almost exclusively with SuperDuty 4WDs... our area is the Great Arboreal Forest that spans much of the mid-north in Canada... Oilfield and logging are our prime industries and a properly maintained front driving axle on one of these trucks is dependable... ("maintain" and "repair" are NOT interchangeable terms).
Lets take a look at how this system operates....
When we set the switch on the dash from 2HI to 4HI.... a series of events occurs.... The module that controls the 4WD system (since 99, this task has been assigned to various modules including the GEM, later a stans alone module and currently, that function *may* be in the SJB (smart junction box) though I would have to check to be sure) would command the appropriate transfer case relay to turn the shift motor. When the shift motor indicates proper positioning for the switch position selection, the module assumes that the transfer case is working properly and that the front driveline has been brought to speed... The appropriate 4WD indicator(s) on the dash will illuminate....
After this happens (and only after this), the module will command the PVH solenoid (pulsed vacuum hub).... to lock the hubs, this will be about a 12 inch vacuum signal that lasts for about 30 seconds (memory thing as far as time allotment). Once the time is up, this vacuum signal is vented to atmosphere... it is NOT a continuous application of vacuum.... These hubs operate something like a click type ballpoint pen. Click it once, the point is out... click it again, the point retracts....
To UNLOCK the hubs, the module will command about 6 inches of vacuum to the hubs... again, after about 30 seconds, this vacuum signal is vented to atmosphere. The hubs will not unlock until the vacuum is vented. While the owners manual no longer states it, it is still a very good plan to wait a bit after disengaging 4WD and back up a few feet to remove any driveline bind that may "trap" a hub in the engaged position.
Now... 6 inches of vacuum is NOT a very strong signal in anyones book.... If there is a leak in any portion of this vacuum system, the hubs will not have enough vacuum applied for them to operate properly. A trip to motorcraft.com and a looking up the recommended service interval for these trucks indicates that the spindle bearings should be service regularly.... at the same time as this service the large steering knuckle should be replaced, the O-ring around the wheel bearing should be replaced and it's a good idea to replace the axle tube dust seal at the same time. conscientious tech will ensure that the bore in the steering knuckle is clean and free of rust at this time....
So - what else can go wrong if the hubs don't work properly.... Too many owners don't pay enough attention to some of the little clues their autos are trying to give them (the guy that's been driving with the CEL on for two years might be one - the guy that's had an odd vibration for a long time but it hasn't really "bothered" him yet might be another)... until the concern decides that it is time for someone to sit up and take notice....
At the transfer case end of the driveshaft to the front axle, there is a double cardan U-joint. This U-joint utilizes a "centering ball" to keep things properly aligned. If the vacuum system is properly maintained, any time the truck is in 2WD, this shaft is only ever "along for the ride". If the hubs are left engaged for long periods of time without 4WD being selected, not only is the centering ball experiencing constant deflection, but the driveshaft spends much of it's time "whipping". Once the centering ball starts to deteriorate, it can self destruct in short order. And the resulting forces can cause the transfer case to virtually explode - something we do see on occasion - checking service history always shows that proper servicing has been neglected....
Have we seen rare failures? You bet - nothing is fool proof.... But, with proper scheduled maintenance, the SuperDuty ESOF is strong, reliable and trouble free...
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Once the centering

If the centering ball is defective, there would be failure, but as long as it is maintained properly, it is OK to run it this way. This is how Jeep Wranglers, Cherokees, and older Grand Cherokees have been designed for years, without any way to disconnect the front hubs. In my experience, the centering ball would not fail without ample prior warning...squeaking, vibration...etc, unless defective.
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There is no maintenance that can be performed on the Ford centering ball... yes, it "should" give ample warning... but this has to be heeded to mean anything.... I have absolutely no experience with any sort of Jeep so I cannot comment on those....
As far as anything else is concerned... I am speaking from my own, personal experience. Without comparing this particular driveshaft to any other driveshafts, the centering ball can and has failed on the SuperDuty front driveshaft.... no amount of discussion can alter that fact....
I respectfully offer that I have worked in the automotive trades for nearly 40 years..... I have been with my current employer ( a mid-sized Ford dealer) for five years and I am currently shop foreman. Most of what we sell and service is the SuperDuty and most of those are diesel powered.... What I see is what I see and I can't go beyond that without getting in to conjecture....
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Then it stands to reason the failed centering balls are defective, perhaps not receiving enough lube upon assembly. Jeep CV joints are of the same design and don't need hublocks to idle the driveshaft in 2wd, but yes, there have been rare failures in that case as well. And it is possible to re-lube them, it means disassembly of the joint, of course.
What's your take on the OP saying two mechanics (one at a Ford dealer) said that you can't go more than 45mph if the hubs are locked?

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Thanks for the info, Jim.
I've hit every regular maintenance point with the vehicle, so if maintenance was missed then Ford dropped the ball. Not an impossibility.
There was a vibration, but only a few seconds before things fell apart. The vibration was followed by a whine ("oops", foot of gas, looking to get off road), followed by the chaos of everything going to pieces.
The truck had 51k, and front hubs were replaced about 43k. Spindle should have been taken care of at the same time.
Who knows what else might have been going on in the transmission, crank-case, etc. that could have contributed. The CV joint had obviously blown, which was the start of the chain reaction.
Rob

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"Hubs" were replaced at 43K, or "hublocks"? That is a different from the bearing assembly, which in the SD is a unit assembly, as opposed to a standard spindle-bearing setup.

How do you know that's where it started? If the CV shaft blew, it would disconnect from the transfer case, and bang around a bit. Explosion of the T case would easily destroy the CV joint in the front driveshaft.
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After re-reading your OP, you are calling the joint on the axle a CV joint. It is a U-joint. The joint on the transfer case end of the front driveshaft is a CV joint.

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No... the "CV" joint, in this case, is the double cardan U-joint at the transfer case front output flange...

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Right. That's what I said. He called it a CV joint on the axle in the original post. There is no CV joint on the axle.

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says...

Hubs. Almost $900 worth of Ford dealer charges.

I guess *I* don't know that's where it started. The centering ball is destroyed (in the CV joint), and the mechanic told me that's what caused crank-case failure.
One question, though. The mechanic told me it was the "crank-case", and the receipt says it was the crank-case. Isn't there BOTH a crank-case and a transfer-case? I should crawl under the thing and study it, I guess. :-)
Rob
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