Re: Dana 300 rear output seal

[jlandry@domain.elided (John A. Landry)]

As the putrid festering facial boil erupted, Matt Palguta
<mpalguta@domain.elided> yelled:

>    I've noticed an apparent leak from the rear output of my Dana 300
>transfer case. There is an arc of flung fluid on the trans tunnel above
>the case. Is this seal available and reasonable to install? Many thanks
>for any info.

Matt,

Dana 20 and Dana 300 output shaft seals are relatively easy to replace with
the transfer case still in the vehicle.  The only difficult part
experienced by some is in removing the nut that holds on the output shaft
yoke.  However, with an appropriate sized socket, a breaker bar, and
possibly a cheater pipe over that, the nut will come loose without trouble.
Most of the difficulty with removing the nut comes from trying to use an
impact wrench... it usually won't budge.  But with a breaker bar it comes
loose.  Just apply the parking brake, put the tranny on park (if an auto)
or put a manual tranny in the lowest gear and choke the tires.  The new
seal should cost less than $10.00 each.

1.  Disconnect the rear drive shaft and move it out of the way.

2.  Remove the yoke retaining nut (see above).

3.  Slide yoke off output shaft (tap with soft hammer if needed).

4.  Using a slide hammer with screw on tip, pull seal.  Note: The seal is
recessed into the transfer case housing which makes using a seal prying
tool difficult if not impossible.  The output shaft is in the way, so a
slide hammer works best.

5.  Install new seal by carefully and evenly tapping with a brass drift
around the outer edge of the seal only.  The seal has to be driven in to
the bottom of the recess in the case.  Be very careful not to tap the seal
anywhere near the rubber lip, or you will distort it and cause leaks.

6.  Clean the yoke.  Using very fine grit polishing paper, Scothbright (tm)
or abrasive cloth, you may even wish to carefully smooth and *polish* (not
sand) the portion of the yoke which rides inside the seal.

7.  Apply a film of gear oil to the seal lip and slide the yoke back on the
output shaft.

8.  Re-install the washer and retaining nut and using your breaker bar,
tighten until your eyes bulge out!  The nut is supposed to be tightened to
a very high torque... much higher than most 1/2" drive torque wrenches
read.  I don't have the figure in front of me, but it's like 230 foot
pounds.

9.  Re-install drive shaft.

The whole job takes less than an hour even if you're slow like me.

Have fun,

John
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