Date:         Wed, 5 Jun 1996 15:44:07 -0500 (CDT)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         jbrill@unlinfo.unl.edu (James Brill)
Subject:      Differential Seal Replacement Procedure

This is for the 'late-type' transmission.  You will have to look at 
the pictures in the Bentley to determine which one you have.  I am 
unsure of the years.  My '71 is 'late-type'.

There is a seal inside of the differential assembly of you 
transmission that might start to leak.  I have been told that they 
rarely do on VW buses.  Mine did.  I had mis-diagnosed it as a much 
bigger problem and had let it drip while I kept my eye on the 
gear oil level.  The drip began to get worse about the time I was 
going to have the engine and cv's out.  I took the opportunity to do 
something about it.  I suppose it could be done with the engine still 
installed but you would lose some hammer swinging room.

You will lose some gear oil when this seal is out.  This might be a 
good time to just replace it all.  It you don't need a change you 
could drain some beforehand and top it up when you are done.

Things you will need for this repair.  The inboard seals, the outer 
sealing caps, and anything else that might need it while the thing is 
apart.  The blowup of the differential in the Bentley shows that you 
will also want to replace the spacer and lockplate seal.  Both of 
these parts were still functional on my bus.  The inboard seal is most
likely what is leaking and you will destroy the outer sealing cap to 
get the thing apart.

After the cv is off, stick a small screwdriver through the center of 
the sealing cap and pry it out.  It should some out easily.  Behind 
that you will find a circlip.  Remove the clip and the joint flange 
will now come off.  The Bentley shows them levering it off with a 
couple of screwdrivers or pry bars.  Next you will find two phillips 
head screws holding on the lockplate.  I found an impact screwdriver 
to be of use here.  I didn't want to strip this screw.  The Bentley 
mentions that the new pockplates are made of plastic.  I found mine to
be a plastic over metal.  Both are these were in usable shape, so I 
did.

Behind this lockplate there is a rubber washer called a 'spacer' in 
the book.  Again, I was able to reuse mine.  It was round on the OD 
but had a flat spot on the ID.  This was down, I assume so that it 
could catch a very small leak.  The last thing to remove is the seal 
itself.  Mine was in there very tight.  This is a tight fitting seal. 
You might consider the purchase of a seal puller to help with this.  
$7 at Sears, a little more at most FLAPS.  It makes the removal of 
seals easier, safer and less damaging to the surrounding area.

One thing to watch for.  There is a thrust ring that slides over the 
differential.  It is able to come off anytime after the joint flange 
has been removed.  I was able to keep it pushed back into the 
transmission housing.  I didn't want to remove it and forget to put it
back.  If you do happen to take it out keep the left and right on 
their respective sides.

For me the hardest part of this job was getting the new seal in there.
As I said before, this is a very tight fitting seal.  I ruined two on 
the first attempts.  After poking around the list and local garage I 
got this great advice.  First of all, make sure that the edge of the 
lip is chamfered.  Mine had a nice angle on it from the factory.  Then
I applied this advice.  I put the new seal in a locking baggie with 
enough new gear oil to get it submerged.  Seal the bag and get out as 
much air as you can.  Then, put the baggie in a bowl and run it under 
hot tap water.  I let it set about ten minutes, changed the water and 
let it set five more.  What this does is soften the rubber on the 
outside surface of the seal.

You don't need to run back out to the garage but you also don't want 
the seal getting cool again.  I put the seal in place and put a big 
washer over the outside of it.  This washer should have a big enough 
ID to fit over the short differential gearshaft but small enough OD to
fit inside of the housing.  Sorry, I don't have the dimensions handy. 
I found mine at the hardware store amongst the 'machine washers'.  I 
find that one of these big washers against the seal does a better job 
for me than the big socket alone.  In this case, a 50mm socket went on
top of the washer and the tapping commenced.  After the heating trick 
it went in as planned.  It is still a very tight fit.

Reassembly is the reverse of removal. :)  The rubber 'spacer' that 
went between the seal and the lockplate was a bit of a challenge until
I coated it with a little gear oil.  That was enough to hold it in 
place until I got the lockplate in.  Again, flat spot down.  After the
joint flange had been circliped in, the sealing cap will probably 
press in with your thumbs.  I used a socket of that diameter and it 
tapped in with very little resistance.

Top up the transmission, install the cv's and go for a drive.  Easy as
that.  One note, the seal you get as a replacement might not look just
like the one you take out.  My replacement was 'deeper' than the one I
took out.  I assume this is to be expected.  There was still room for 
it to go in there. After checking with a dealer and a VW FLAPS I was 
sure I had the correct seal.  The fiche had chassis numbers at least.

That is it.  I only have a few hundred miles on it but it remains dry.
Thanks go to Bob Hoover for the gear oil in the baggie trick.  I was 
one very frustrated guy until I got that advice.  Corrections and 
comments welcomed.  

Jim
-- 
James A. Brill Jr.         \\  //
jbrill@unlinfo.unl.edu   \\ \\// //   
University of Nebraska    \\//\\//     
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