hi
I'm new to the forum and ford trucks (dad has a 62 but i have only driven it never worked on it). So i just got a 1991 f250 4x4 long bed with the 351w and a 4 speed auto. My buddy (who has an 87 f150) was looking and when I'm in 2 high with the hubs unlocked the front drive shaft is still engaged. I'm new to 4x4 so i don't know if this is normal or not. It is also hard to get the transfer case into neutral and back. When i drive the truck shutters. The past owner said he thought it was the transmission but never looked into it. Now I was wondering if this was a transfer case issue with this model or what it could be. 2 High works great though.
Thanks for any responses.

 

Your not in 2wd. If the hubs are unlocked then the transfer case is in 4wd.

 

so if its in 2H and the hubs are set to free its still in 4 wheel? this is my first 4x4 so please bear with me.

 

the front driveshaft can still turn when everything is in 2 wheel drive.
to test if the hubs and transfer case are indeed in 2 wheel, engine off. trans in park. t-case in 2 wheel. hubs unlocked.
get under truck and try to turn front driveshaft. if it turns, it is in 2 wheel drive.

if the drive shaft does not turn, jack up a front wheel and turn the wheel. if it turns, the hub is unlocked. do this for both wheels. if they are both unlocked and turn, the problem is in the transfer case.

 

Not
Good!

The frond shaft shouldnt be spinning in 2 high, only 4 high and 4 low if you have it.

I would start with changing the transfer case fluid, see if any chunks fall out. Depending on your setup, you may be able to adjust your tcase lever so it will fully disengage?

It is not good to run with the shaft spinning like that, it will wear it out. My manual says not to run like that with the hubs unlocked.

The only other possibility is one of your hubs is stuck
Engaged, and that is spinning the front drive shaft when the truck moves. I would temporarily remove the hub locks and see what happens.

 

the front drive shafts on all 7 of my trucks will still turn slightly when everything is in 2 wheel drive. just because everything is locked, does not mean they are locked so htey do not move.
there is enough friction in the associated pasts that the shaft will still spin.
it is just not engaged.

 

I agree. Many of my 4x4 trucks have exhibited the same thing.

 

Good thing to check, but not quite the right way to check it.

(By the way, all of the following is assuming you have manual hubs. You said they were in the free position, which seems to imply there's a dial on them that's pointing to "free." If that's the case you do have manual hubs. Auto hubs would change the diagnostic steps.)

First crawl under and try to turn the drive shaft as tjc described. If it won't turn then both of your hubs are locked and/or your t.case is stuck in 4wd.

So if the driveshaft turns you can be sure that the t.case is good, and if it doesn't you can be pretty sure the problem is in your t.case

Whether the driveshaft turns or not, jack up one front wheel and try to spin it while watching the U-joint in the steering knuckle on the same side. If the tire won't spin, or if it spins and the U-joint spins with it, then that hub isn't unlocking. Do the same with the other side as well.

If your t.case is in 2wd and only one hub is locked you will still be able to turn the driveshaft. Just spinning the tire without looking to see if the axle is turning on that side won't necessarily tell you anything about that hub. That hub could be locked but the opposite one unlocked and you're spinning the differential.

 

If one hub is staying locked and the other one free, that could be the shudder because it is spinning the differential at double speed backwards!

 

damn it!!! thanks for the catch on my brain fart Bob!!!

my head has not been wrapped too tight the past week.
i am just getting over a bad bout with the flu, and Dad has not been doing too good.
but he is doing much better now, and i am feeling a bit better too.

 

No problem. I can't tell you how many times I rewrote my post, trying to get it correct and readable. It's just so simple when I think about it! But writing it down is a whole nother thing

 

One thing not covered is if the hubs were installed wrong. If someone had them apart you never know. If one hub is locked the other will still turn.

 

ok. It does have manual hubs. so i crawled under and with the hubs in the the free position the drive shaft moves. When i put it in locked it doesn't. The Tcase is in 2 high and i made sure that the lever was locked in. I haven't had the chance to jack it up. So if I understand right that is good because the hubs are locking and unlocking. just so we are clear for 2H the hubs should be locked right?
I know it sucks trying to help the new guy that doesn't know anything but thanks to all who are walking me through this.

 

That all depends.

If you may want to engage the front axle at any time then you want the hubs locked. If you don't want to be burning fuel to drive the front axle and driveshaft through the front tires then you want the front hubs unlocked.

To put it another way, driving in 2H with the hubs unlocked will be a little cheaper, but it'll take a little longer to go to 4WD; while driving in 2H with the hubs locked will let you get into 4WD in the time it takes to move the shift lever, while it'll cost a little more per mile to drive.

And you want the hubs locked if you're in 4WD, either high range or low range.

None of us was born knowing this stuff. Every one of us started from somewhere.

 

Sounds like everything is checking out, but it's still possible that one of the hubs is hanging up. If it's too much of a pain to jack it up, with the t.case in 2wd and only one hub locked (the other free) try turning the driveshaft. It should turn. Then unlock that hub and lock the other. Again the driveshaft should turn.

If you can't turn the driveshaft one of those two times it means the hub that is unlocked isn't really and it's sticking engaged.

If the driveshaft turns both of those times then everything is disengaging fine, which is good news except that it means we aren't figuring out why your truck shudders.

As far as the transfer case shifting hard, try putting the transmission in neutral before you shift the t.case. That will keep you from loading up the gears.