87 stock toyota 4x4. Getting an awful intermittent "grinding" noise from what I thought was drivers side hub. It comes and goes. Only occurs in 4x4. No noise in 2wheel drive. That tells me it's probably the hub. I've had it apart and everything seems OK. Replaced, repacked front bearings, locking hub operates fine. No metal dust or shavings or sign of damaged metal anywhere. Doesn't generate any excessive heat from friction but it sure sounds bad. Not like metal on metal grinding but more like a dry chaffing sound. Hard to explain. I've been working on my own ˟˟˟˟ for over 30 yrs and have never heard anything like this before. I'm at a loss. Brass bushings in the hub maybe? Cannot find any specs for them. Thrust on the axle is within spec. Expanding my search to include the differential but I cannot get the drain plug to break loose. I've put the breaker bar on it until the socket pops off the plug. Any tricks here? I sprayed it with PB. Thinking I may weld a1/2 in drive socket to it so I can really get a grab with the breaker bar. I don't want to pull the drain plug until I get the fill plug loose.

 

If it's only in 4wd and the hub actually locks, that would tell you that it cannot be the lockout hub.

Nothing in the hub turns against anything else when the hub is locked.

 

Update. Got fill plug loose. Diff was as it should be. Oil was clean and in good condition.

Can anyone tell me how much play should be between axle shaft and the brass bushings in the wheel hub/ knuckle?

 

Have you tried jacking up the wheels (all four) and see what it does noise-wise going in and out of 4WD? I'm assuming you have the automatic hubs, but the test is valid either way. That'd be my next step.

 

The play is only measured and changed by the washer thing on the outside of shaft, that threads into the shaft. The manual only specifies axial play, not 'sideways'. or radially.

I will look for my fsm if you need to know exactly. But this was a week ago so guessin' your way past that point.