Front Drive Shaft (1 Viewer)

[SH220]

Hi all,

I recently picked up a 60 series and was getting a rumble from the front drive shaft at anything over 60 MPH. I replaced both U joints and was carefull to mark the driveshaft to replace in alignment. It is also correctly in phase. While the vibration is reduced it still is rumbling above 60 and I suspect the driveshaft is out of balance.
I have free wheeling hubs. My first question is, if the front hubs are unlocked and the truck is in 2wd, why is the front driveshaft even spinning? Isn’t that the point of free wheeling to save the front diff from turning?? If I’m thinking about that incorrectly, how hard is it to balance and should I take that on myself?
Thanks!!!

 

[FJ Silver]

Hey,
It sounds like your transfer case isn't disengaging from 4 to 2WD. It would make sense to rumble at higher speeds in that case. It could be other things like the prop shaft being inbalanced, wheelbearings or u joints. But if you're in 4WD always, that's the obvious answer.

 

[LazarusTaxa]

Def shouldn't be rotating if the hubs are unlocked and the xfer case is in 2wd

 

[ChaserFJ60]

was the FJ60 sitting for a long time? Are the hubs disengaged or are they stuck