Help - front Dif is not unlocking

[Paul Heneghan]

> From: Penasack_Tim at emc.com
> The front dif on my 86 4KQ is not unlocking but the rear locks
> and unlocks.
> If I put the car on 4 jack stands and run it - it usually unlocks. Haven't
> tried it since my last spirited drive.

On my 1984 80q (same car), the centre diff (you can't lock the front diff -
I presume you mean the centre diff) has always been a bit unwilling to
unlock than the rear diff.  Probably something to do with the extra linkage
that goes from the actuator on the rear diff to the locking lever on the
centre diff.  I remember once driving 20 miles on a motorway waiting for the
centre diff to unlock and it never did.

Ways to unlock it include:
Spirited driving - it often unlocks as the revs drop when changing from 2nd
to 3rd gear change (due to increased vacuum ?).
Drive it in reverse for a couple of seconds
Turn a corner.

Once when all these techniques failed, I checked it out and found that
although the linkage was OK, the rear diff mountings had totally
disintegrated.  Replacing those sorted out the diff locking problem.

Paul