Date: Thu, 5 Jul 2001 18:21:31 -0400
Reply-To: Derek Drew <derekdrew@RCN.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Derek Drew <derekdrew@RCN.COM>
Subject: How To Install Your New VC
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OK Brian. You are one of many people asking me for a definitive guide to
replacing your VC. So for the benefit of the archives, here goes the best
most current version of these instructions. No special tools or
automotive experience are needed for this job, and because it is so
simple, it should not be farmed out to a transmission shop. The best
thing I could say, going from memory, is to....<br>
<br>
1. Drive van up on 4 ramps <br>
2. Put jackstands under van in case ramps fail<br>
3. Record and mark the alignment of the driveshaft to the front
differential so that you can put the same bolt through the same holes of
each unit upon reassembly. This will reduce the chances of your ending up
with an out of balance driveshaft on reassembly. <br>
3. Unbolt the four forward bolts holding the driveshaft on with either a
1/2 inch or 13mm open end wrench and some liquid wrench. If the 13mm
wrench doesn't work that great, try the 1/2 inch open end wrench.<br>
4. Loosen the bolts holding the front differential so that differential
may be shifted around. <br>
5. Shift the front diff forward so that the driveshaft will fall away
from the front diff. Shift that driveshaft out of the way. <br>
6. Remove the oil from the front diff through the oil drain hole. Throw
that oil away by bringing it to your nearest auto repair shop for
disposal. <br>
7. Remove the 13ish? 13?mm bolts holding the back half of the front
differential onto the vehicle and then pop the rear third of the
differential off backwards. Do not looosen the big bolt at the rearmost
point in the front differential <br>
8. Have something on the ground to catch the residual oil that will spill
out. <br>
9. Pull the VC out and replace, being careful to reinstall the little
metal washer that is wedged in there. No special tools or measurements of
any kind are needed. <br>
10. Bolt everything back together, but bolt the front differential down
last after shifting it around to properly seat it in relation to the rear
transmission. When bolting the driveshaft back on, either replace the 4
driveshaft nuts with factory new ones the way VW says to do it (proper
way), or just use Red Loctite the way about half the people on the list
do it (universal list method) or reuse the original nuts with no loctitie
the way the other half does it (pogo stick method; see below). <br>
11. Refill the front differential with GL-5 Transmission oil using the
factory specified viscocity. Mobil 1 makes a good GL-5 for the front
diff. (Make sure not to use GL-5 in the rear transmission, however, as
that takes only GL-4--eveybody wisely uses Redline GL-4 synthetic for the
rear.) <br>
12. The entire job should take you about 1 hour. But for some reason --I
cannot predict in advance why -- it will actually take you 5 hours :-).
Some members have reported broken bolts holding the diff in place, or
broken rubber mounts, so be prepared to hunt these parts down if you
decide you need to replace them. <br>
13. Some people decide to remove the diff entirely to do this job. You
can do that, but that means you have to disconnect the front CV joints,
which is a pain. Still, those front CV joints probably need their grease
to be renewed anyway. And as long as you are regreasing the inner front
cv joints, you might as well do the outers too, and inspect the
boots, and then why not the rears and HEY lets not loose focus here...
<br>
14. The best description on how to change your VC was originally posted
to the list by Rainer about three years ago, but Steve Schwenks photo
essay matched this post in utility and interest. Too bad it is not on
syncro.org right now. I will copy Ranier's post below. <br>
ABOUT THE POGO STICK METHOD. <br>
This is actually a method of easily removing the transmission and engine
from the vehicle. Essentially, the procedure is to skip using loctite on
the nuts that hold the driveshaft on the front diff, and don't replace
those nuts with new nuts either. Just reuse your old nuts even though the
factory says to replace them. When the nuts or bolts eventually fail, the
driveshaft will drop down on the highway and get lodged on a rock, crack,
or other obstacle and remove your trannsmission and engine in about two
seconds. This also works in the event of a front U-joint failure. If this
does not appeal to you, install a strap that holds up the front
driveshaft in the event its front attachment point fails. I haven't put
my strap in yet myself, but I think about it from time to time.
<br>
<br>
<blockquote type=cite cite><blockquote type=cite cite>There is an
excellent article by Steve on how to replace the VC at
<a href="http://www.syncro.org/" eudora="autourl">www.syncro.org</a> in
the Tech section called "Replacing the VC (photos):
</blockquote></blockquote><br>
Reproduced below is Rainer's version of the above. It differs from my
version in some important respects so it pays to read both posts. Note
that Rainer is one of the world's leading observers of the Syncro Viscous
Coupling, and is of much higher intellect than the average Vanagon or
Syncro poster so we are lucky to have him among us. <br>
<br>
<blockquote type=cite cite>VW's original (German) repair manual doesn't
say much about how to test<br>
the viscous coupling. They only recommend placing the rear
wheels in a<br>
break testing stand. If you then switch to the G-gear
(creeping gear),<br>
the front wheels should move the van out of the test
stand as soon as<br>
the engine is revving slightly above idle. If the front
wheels fail to<br>
do so the viscous coupling is to be replaced, VW says. VW
adds another<br>
tiny sentence to this, saying that only when the engine
is revving at<br>
idle and with the G-gear switched in, the viscous coupling is
able to<br>
absorb all the torque to the front wheels and keep them from
moving.<br>
<br>
To me this last and rather
ill-formulated (in the German manual)<br>
sentence is the key to testing the viscous coupling. For in
most cases<br>
we are not dealing with viscous couplings doing less than
their share,<br>
but rather with hard-going viscous couplings which don't have a
problem<br>
at all in moving the van out of the test stand
with the engine just<br>
idling.<br>
<br>
Thus the really important thing here is not the van successfully
leaving<br>
the test stand. On the contrary, the important thing
here is the van<br>
not moving and staying put in the test stand with the G-gear switched
in<br>
and the engine just idling. If your Syncro doesn't pass this
test your<br>
viscous coupling is probably worn out and ready for a
replacement. Or<br>
put the other way round: as long as your
van's viscous coupling is<br>
working properly you will not notice your van has got one.<br>
<br>
As soon as you are encountering
problems with your Syncro when<br>
cornering, in particular after a long and fast drive, or as
soon as --<br>
despite of power steering -- steering
becomes a bit difficult when<br>
turning and the Syncro slows down considerably when going round a
corner<br>
... as soon as one or more of these things are happening,
your viscous<br>
coupling is most probably due for replacement.
When the tires start<br>
whining while cornering it might well be too late already ...<br>
<br>
I once had all of these symptoms and it was immediately clear to me
that<br>
the viscous coupling was the culprit. But it took some
time for me to<br>
react, and it took some more time for the new viscous coupling to
arrive<br>
at my door. Should you ever encounter similar problems I would urge
you<br>
to immediately get under your van and remove the
drive shaft between<br>
gearbox and front diff. If you fail to do
this and wait too long,<br>
severe damage to the gearbox and/or front diff is the
probable result.<br>
Removing the drive shaft is pretty straight forward, just four bolts
and<br>
nuts (13 mm) on either end of the drive
shaft. Then loosen (just<br>
loosen, don't remove them) the three nuts and bolts (17 mm)
which hold<br>
the front diff in place, so the front diff can move out of the way a
bit<br>
for the drive shaft to be removable. Don't forget to again
tighten the<br>
17 mm screws.<br>
<br>
When I was shopping for a new
viscous coupling (according to all<br>
reliable sources I contacted they cannot be repaired) I
asked several<br>
knowledgable people how long a viscous coupling is
expected to last.<br>
Apart from "it depends" (an employee at
Steyr-Daimler-Puch in Austria,<br>
the firm which was producing the Syncros and in particular
the viscous<br>
couplings for VW) the answers ranged from "some 60,000
km" to "between<br>
170,000 and 200,000 km". Mine was
replaced after 150,000 km but I<br>
bought the Syncro with 80,000 km on the tach and don't
know for sure<br>
whether or not this was still the first
viscous coupling. But I'm<br>
assuming it was.<br>
<br>
As for the reason why the silicone in the viscous
coupling gets too<br>
stiff and starts causing trouble the
people I asked unanimously<br>
answered: to much strain. However, this is not referring to
relentless<br>
off road driving in groundless mud, but rather to small
but permanent<br>
differences in rotational speed between front and rear axle while
doing<br>
normal on road driving. These differences in
rotational speed can be<br>
caused by such things as unequal tire wear or different tire
pressure.<br>
Tire diameters should be the same within a 2 to 4 mm
tolerance. Or, in<br>
other words, if you're measuring the depths
of the grooves in your<br>
tires, the differences should not exceed 1 to 2 mm.<br>
<br>
Thus people not caring tire pressure and
tire wear, people having<br>
mounted different tire brands on the front and rear
axles, as well as<br>
people never routinely using their spare tire so it
gets worn roughly<br>
the same way as the other tires are most probably ruining their
viscous<br>
coupling pretty fast.<br>
<br>
Removing the drive shaft as an emergency measure:<br>
If you have to, and provided you're slim enough,
you can remove the<br>
drive shaft on the bare ground (at least if it's
a Syncro 16"), just<br>
with a little help of the factory jack. In case
your driveshaft was<br>
balanced in its current position, it may be a
good idea to mark the<br>
alignment points of the flanges before removal. Then you'll have to
use<br>
a pair of 13mm wrenches (due to space constraints only open wrenches
are<br>
usable) to remove four bolts and nuts at either end of the
drive shaft<br>
(sometimes the nuts are only 12mm). If you
want to do it properly<br>
you'll also have to loosen (only loosen, don't remove!) the
three nuts<br>
and bolts (17 mm) which hold the front diff in place via
rubber stops,<br>
so the front diff can move out of the way a bit for the drive
shaft to<br>
be removable. However, when lying on the bare ground just below the
van<br>
this might be hard to do. If your drive
shaft has got this rubber<br>
element in it you may try to simply use a screw
driver to cautiously<br>
separate the two flanges at one end of the drive shaft. Knocking
gently<br>
at the flanges at the other end will then take the drive shaft
down. As<br>
to the rubber element: in diesel engined and FI vans the rubber
element<br>
was facing opposite sides. Thus you'd
better take some notes as to<br>
whether the rubber element is at the gearbox end or at
the front diff<br>
end.<br>
<br>
Replacing the viscous coupling:<br>
To replace the viscous coupling
you'll have to pull the front<br>
differential first. I don't think it's feasible to replace
the viscous<br>
coupling right under the van with the front
differential in place. </blockquote><br>
<b>Derek's Note:</b> <br>
Californians on the list proved otherwise so if you want to leave the
diff in there go ahead. Sam Walters did it on the ground, but he
indicated it was a pain.<br>
<br>
<blockquote type=cite cite>In<br>
particular, reassembly would thus be much more difficult and would
cause<br>
plenty of cursing. And you'd have to drain the oil first. By
and large<br>
there is no witchcraft involved in pulling the
front diff, but you<br>
should do it with the van on a lifting platform or above a
grease-pit.<br>
And it takes two people as well as a floor-jack.<br>
<br>
First of all losen but don't yet remove the
three 17mm nuts already<br>
mentioned which hold the front diff in place. Then
remove the speedo<br>
cable as well as the six screws in each of the
inner CV-joints. For<br>
this screws you'll need either a 6mm
hexagonal or an 8mm multipoint<br>
socket. If you haven't done it yet you should
now remove the drive<br>
shaft as described above. If you
have a front diff lock (never<br>
officially exported to the US) unplug
it electrically as well as<br>
pneumatically (tag the pipes so you can't
confuse them later). Now<br>
remove the screw holding the vent pipe of the
differential and then<br>
remove the three 17mm nuts and bolts holding the front
diff. Get the<br>
floor-jack in place and remove the front and rear
mounting brackets.<br>
Then together with a second person cautiously
move the diff forward<br>
along the skid plate and out. Look out for the diff
lock if there is<br>
one.<br>
<br>
Place the front diff on your workbench in such a way that the flange
for<br>
the drive shaft is facing upwards. You can now
easily remove the ten<br>
13mm bolts with which the housing of the viscous coupling is attached
to<br>
the front diff without risking any oil leaking. Lift the
housing which<br>
is containing the input shaft. You will now see
the viscous coupling<br>
itself and a little spacing collar sitting on
top of it. Take this<br>
spacing collar, grease the top rim of it and again place it on the
input<br>
shaft in the housing and slightly press it with its greased rim
against<br>
the bearing so it will stay there. This will greatly ease
reassembling<br>
the diff later. Now remove the old viscous coupling and put
in the new<br>
one. Then apply silicone sealing compound to the contact
flange of the<br>
housing and, inserting the input shaft into the viscous
coupling, put<br>
the housing back in place. Finally, gently tighten the
ten 13mm bolts<br>
crosswise, applying 20 Nm (15 ft lb.), and your front diff is
ready to<br>
be reinstalled.<br>
<br>
Perhaps you should use the opportunity while the diff is
still sitting<br>
on your workbench to check what has been caught by the
magnet at the<br>
oil drain plug.<br>
<br>
To reinstall the front diff in the van simply reverse the steps laid
out<br>
above, at the very last fastening the screws
of the front and rear<br>
mounting brackets as well as the three 17mm bolts
through the rubber<br>
stops (apply 45 Nm (33 ft lb.) to these).<br>
<br>
Tools and torques needed:<br>
<br>
Installation of the front diff:<br>
17mm socket and ratchet, perhaps with extension.
Use 17mm wrench to<br>
counter at the other side, 45 Nm (33 ft lb.)<br>
VC housing:<br>
13mm socket with extension and ratchet, 20 Nm (15 ft
lb.)<br>
CV-joints:<br>
either 6mm hexagonal or 8mm multipoint
socket with extension and<br>
ratchet, 35 Nm (26 ft lb.)<br>
Drive shaft:<br>
Two open 13mm wrenches (sometimes only 12mm for the
nuts), 35 Nm (26<br>
ft lb.)<br>
Acknowledgements:<br>
Special thanks go to Wolfgang Carolsfeld in Canada
<wolfgang@island.net><br>
who not only proofread this text, helped me with some technical
English<br>
terms I failed to find in my dictionary, and did the
math involved in<br>
converting the torques from Nm to ft lb,
but who also successfully<br>
applied the underlying German version of this text to his Syncro to
make<br>
sure it works :-) <br>
----------------------------------------------------------------------<br>
| Rainer M
Woitok
| Phone: (+49-9131) 85-27811,-27031 |<br>
| Regionales
Rechenzentrum
|
|<br>
| Friedrich-Alexander-Universitaet | Fax : (+49-9131) 30 29
41 |<br>
| Martens-Strasse
1
| Telex: d 629 755 tf
erl |<br>
| D-91058
Erlangen
|
|<br>
|
Germany
| Mail: Woitok@RRZE.Uni-Erlangen.DE |<br>
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| 
