Well, with the snow on the ground now I had to lock the hubs in the other day................my vibration's back!
It's vibrating in 2wd as well as 4wd, albeit worse in 4wd.
It seems to be bad when accelerating above 40mph and then evens out, but cruising at 60 then letting off the fuel will bring it back REAL bad.
It's there weather your on the fuel or not and above approx 40mph.
I've check the u-joints and all the usual "things", the only thing I can think of at this point is the 4" lift and the axles not having been shimmed. I bought the truck with the lift and am not sure what degree shim to put in.
I'm also leaning towards having a front driveshaft built with double cardan joints at both ends but don't want this expense if it's going to turn out to be something else.

Any ideas?

Thanks,

 

Have you rebuilt the double cardan joint?

 

Mine vibrates also. My double cardan joint has a little play and the spline on the shaft also has just a little play so mine vibrates at about the same speed. I will rebuild it some day.

 

The double cardan isn't TOO hard to do. Better off to rebuild it BEFORE it breaks.

 

I don't remember if it was on this truck or the '00 I had that I rebuilt the joint.
I'll bundle up right away and go have a look. It's supposed to get to about -22c tonight (-16c right now) and I don't have a shop so the sooner I get out there the warmer (?) it'll still be.

 

Pull the shaft off and take it inside...... Rebuild it on the kitchen table where it is warm.......

 

You beat me to it......Ditto that!

 

First off I shouldn't say I DON'T have a shop, I do have a little garage with a wood stove but the truck won't fit under the 7' door, AND it won't even fit in the barn. At least if I can get the shaft off and in, I could warm it up enough to work on.
Second, the kitchen table is where the deer's being de-boned so there's no room there for the shaft.

 

Gotta prioritize........

 

Does the slip and stub have any play? and yes rebuild the Double Cardin before it breaks

Even with the terrible angle on my front joint my front shaft doesn't vibrate.

You probly wont like the pinion shims it will make it handle erraticly. I just took my 4* shims back out today as I won't be putting to much load on the front shaft this winter, the only reason I put em in there was because I kept eatin joints sled pulling. But the driveline angle was correct with them in

 

Ok, just got back in the house.
The Cardin joint all seems good and firm with no play. The front u-joint is all good.There IS a slight bit of play at the slip yoke but nothing I'd be concerned with right now.
What I DID find however is this:
While unbolting the front u-joint I left the hubs in the lock position. Once I put a socket on the u-joint strap bolt and added a bit of force to loosen, I noticed that the r/h steering knuckle u-joint had some up/down motion to it. It appears that the whole right side axle shaft is wanting to move up & down. This is now leading me to believe that the needle bearings in the spindle are worn out allowing the shaft to run in an oval pattern as apposed to circular thus giving an exagerated vibration similar to a wheel/tire out of round. The l/h steering joint seems fine, it's just the short side (r/h). I DO have a seal leak on the r/h side of the axle tube as well, I just can't afford the $600 bill to change the axle seals right now. I can't see the carrier causing this issue but I can see that the spindle needle bearing being hooped and the cause of my greif.
Sound plausable?

I've got a spare F-250 HD twin I-beam 4x4 front axle asembly(1997) around that,if the spindles are interchangeable,I could re-bearing and then just swap out when time/weather would allow. I know the hubs are interchangeable at least, I've got those ready as spares.

 

Mine had the same problem as yours. It turned out to be the wheel bearing. It will only run about ten miles after they seize up before the wheel fals off!