4x4 noise

[partsman]

i recently had no 4x4 and replaced motor on transfer case that restored that. 4x4 is working and i have a noise sounds like buzzing through drivers floor board. i thought it was a hub issue so i replaced that but still have the noise i would appreciate some help on this matter.
thanks

 

[blu72]

did you check your wheel bearings while you were checking the hubs?

 

[tenikiwon]

Does it do it in 2WD/AUTO/4WD/4LO? Any difference in the noise? What about backing it up? Reving it?

 

[partsman]

yes bearings looked fine. noise onle occurs when in 4x4 going forward and reverse. if i turn 4x4 off and drive with hubs engaged noise is still there. when i back up to unlock the hubs when the unlock noise is gone. seems like it is only when drive train is locked in. i replaced hubs with fac ford units also.

 

[tenikiwon]

Try it in 4WD with hubs unlocked (if you have manual) Maybe your front Diffy took some water a dirt.

 

[MrShorty]

Does the "buzz" vary with engine speed or vehicle speed?

 

[partsman]

it veries with vehicle speed. could it be a spindle or spindle bearing?

 

[tenikiwon]

What about revving in neutral or coasting on the road?

 

[partsman]

it makes noise only with vehicle motion.

 

[MrShorty]

So it occurs with the hubs locked in 2H, 4H, or 4L.
Dissappears when the hubs are unlocked.
Is independent of engine speed, but varies as vehicle speed varies. This all suggests that it is in the front drivetrain somewhere, but not the wheels. I'd start by checking u-joints on the driveshaft and the axles, check t-case fluid level/condition, check for stuff (mud/grime) on front driveline that could throw it off balance.