Re: Center Diff Noise on 4ksq

[steveb@falcon.kla.com (Steven Buchholz)]

> I was playing around with the differential locks the other day and while
> stopped at a light, car in neutral with the center diff locked, there
> was a deep hum and a vibration that is not present when the center
> differential isn't locked.  Is this normal?  Also, it seemed to take
> quite a while for the diff to unlock, while under way, this was on a
> straight piece of road.  Anything to be concerned about? 
> 
I have also noticed on the '83 urQ that when the diffs are locked the 
car seems different even when sitting still ... some of that difference
being audible ... but I've never tried to isolate the source.  If you 
think about it with the drive train sitting idle there isn't much it 
could be.  About the only thing that comes to mind is that there may be 
some residual torque in the prop shaft and rear half-shafts.  It seems 
that the '88 5kq does not behave this way though.

If you have an older 4kq there is a cable that connects the actuator on 
the rear diff to the center diff on the tranny.  I notice that the center 
diff is much more sluggish to engage/disengage on the urQ too.  I figure 
it is a combination of an old cable, an old actuator and long vacuum lines 
along with a little built up torque that makes it want to stay locked.  I 
find that I sometimes have to help by steering left and right slightly to 
try to eliminate the binding.  I do not hear any popping sound when the 
diff finally unlocks ...

HTH!
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)