2000 F250 7.3 4x4 ext cab with a vibration coming from what feels like the front hub. I quick switch to 4x4 momentarily and the vibration ceases. Then a while later it comes back and the cycle continues.

I just changed the thrust bearing and it seemd to help, but fix it. I noticed at the knuckle area where the front shaft universal joint is, there seems to be an aweful lot of play or slop in the axle where it goes into the differential. Is that normal, or is there something worn?

 

How much slop? I think around 1/4" is pretty typical. Have you checked the u-joints?

 

When you say thrust bearing, do you mean the needle bearings, inside of the unit bearing? (one the holds you wheel) There will "feel" like there is play, on the axleshaft that goes into the differential. The shaft slides into the spider gear, and the only other thing that holds it is the inner axle seal. If you havent replaced those yet, they are likely getting to be not as stiff as they were, and youll eventually notice gear oil coming from were the axleshaft goes in.

 

The hub itself might be going bad. I know when mine started it moved quite a bit at first and then when I replaced it it moved a whole lot like the whell would fall off when you jacked it up.

 

I didn't really think the shaft was supposed to move at all. There appears tpo be some kind of dust ring of some sort right whre the shaft goes into the differential that are loose and floating as well. So far there is no oil leaking from either side, and the universals other than being rusty looking isn't showing anything ominous. I just thought the shaft floating around like that was odd.

Yes I mean the needle bearings. The dealer showed them as "Thrust bearings" located on the back end. NAPA found them under the same name when I went there after the dealer said they didn't have any in stock. I replaced the left front, and cleaned up everything else and the the flutter for now has gone away. I hope to do the otyher side this weekend.

 

Hope you got it fixed, sounds like you did. Thanks for following up with it.

 

100_0294.flv video by triskit16 - Photobucket

I had a lot of play in mine as well. So much so the upper ball joint grease fitting looked like a dime welded to a piece of metal.

Knuckle seal was shot...
Replaced it and it went away. My only symptom was the play and the clank noise when goin over bump, not the vibration.

Glad you got it fixed!