Date: Thu, 5 Jul 2001 15:40:21 -0700
Reply-To: steve@SYNCRO.ORG
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Steve Schwenk <steve@SYNCRO.ORG>
Subject: Re: How To Install Your New VC
Content-Type: text/plain; charset=us-ascii
At steps 7-9 it might be noted that it is a little
tricky removing the casing to get to the VC. It can
hang up on the Diff. mount bar, the one in a "U" shape,
and I had to remove that bar to get it off and out of
the way.
Any one have the part numbers handy for the drive shaft
nuts that must be replaced?
I will be upgrading the syncro.org site soon and will
restore the photos for the VC change. The site where i
had the photos stored went under. Peter dug them up
for me and I can send them out till the site is fixed
again. Maybe I can use this description on the site?
Steve
Derek Drew wrote:
>
> 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....
>
> 1. Drive van up on 4 ramps
> 2. Put jackstands under van in case ramps fail
> 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.
> 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.
> 4. Loosen the bolts holding the front differential so
> that differential may be shifted around.
> 5. Shift the front diff forward so that the
> driveshaft will fall away from the front diff. Shift
> that driveshaft out of the way.
> 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.
> 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
> 8. Have something on the ground to catch the residual
> oil that will spill out.
> 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.
> 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).
> 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.)
> 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.
> 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...
> 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.
> ABOUT THE POGO STICK METHOD.
> 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.
>
> >> There is an excellent article by Steve on how to
> >> replace the VC at www.syncro.org in the Tech
> >> section called "Replacing the VC (photos):
> >
>
> 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.
>
> > VW's original (German) repair manual doesn't say
> > much about how to test
> > the viscous coupling. They only recommend placing
> > the rear wheels in a
> > break testing stand. If you then switch to the
> > G-gear (creeping gear),
> > the front wheels should move the van out of the
> > test stand as soon as
> > the engine is revving slightly above idle. If the
> > front wheels fail to
> > do so the viscous coupling is to be replaced, VW
> > says. VW adds another
> > tiny sentence to this, saying that only when the
> > engine is revving at
> > idle and with the G-gear switched in, the viscous
> > coupling is able to
> > absorb all the torque to the front wheels and keep
> > them from moving.
> >
> > To me this last and rather ill-formulated (in
> > the German manual)
> > sentence is the key to testing the viscous
> > coupling. For in most cases
> > we are not dealing with viscous couplings doing
> > less than their share,
> > but rather with hard-going viscous couplings which
> > don't have a problem
> > at all in moving the van out of the test stand
> > with the engine just
> > idling.
> >
> > Thus the really important thing here is not the van
> > successfully leaving
> > the test stand. On the contrary, the important
> > thing here is the van
> > not moving and staying put in the test stand with
> > the G-gear switched in
> > and the engine just idling. If your Syncro
> > doesn't pass this test your
> > viscous coupling is probably worn out and ready
> > for a replacement. Or
> > put the other way round: as long as your van's
> > viscous coupling is
> > working properly you will not notice your van has
> > got one.
> >
> > As soon as you are encountering problems
> > with your Syncro when
> > cornering, in particular after a long and fast
> > drive, or as soon as --
> > despite of power steering -- steering becomes
> > a bit difficult when
> > turning and the Syncro slows down considerably when
> > going round a corner
> > ... as soon as one or more of these things are
> > happening, your viscous
> > coupling is most probably due for replacement.
> > When the tires start
> > whining while cornering it might well be too late
> > already ...
> >
> > I once had all of these symptoms and it was
> > immediately clear to me that
> > the viscous coupling was the culprit. But it
> > took some time for me to
> > react, and it took some more time for the new
> > viscous coupling to arrive
> > at my door. Should you ever encounter similar
> > problems I would urge you
> > to immediately get under your van and remove
> > the drive shaft between
> > gearbox and front diff. If you fail to do
> > this and wait too long,
> > severe damage to the gearbox and/or front diff is
> > the probable result.
> > Removing the drive shaft is pretty straight
> > forward, just four bolts and
> > nuts (13 mm) on either end of the drive
> > shaft. Then loosen (just
> > loosen, don't remove them) the three nuts and
> > bolts (17 mm) which hold
> > the front diff in place, so the front diff can move
> > out of the way a bit
> > for the drive shaft to be removable. Don't forget
> > to again tighten the
> > 17 mm screws.
> >
> > When I was shopping for a new viscous
> > coupling (according to all
> > reliable sources I contacted they cannot be
> > repaired) I asked several
> > knowledgable people how long a viscous coupling
> > is expected to last.
> > Apart from "it depends" (an employee at
> > Steyr-Daimler-Puch in Austria,
> > the firm which was producing the Syncros and in
> > particular the viscous
> > couplings for VW) the answers ranged from "some
> > 60,000 km" to "between
> > 170,000 and 200,000 km". Mine was replaced
> > after 150,000 km but I
> > bought the Syncro with 80,000 km on the tach and
> > don't know for sure
> > whether or not this was still the first
> > viscous coupling. But I'm
> > assuming it was.
> >
> > As for the reason why the silicone in the
> > viscous coupling gets too
> > stiff and starts causing trouble the people
> > I asked unanimously
> > answered: to much strain. However, this is not
> > referring to relentless
> > off road driving in groundless mud, but rather
> > to small but permanent
> > differences in rotational speed between front and
> > rear axle while doing
> > normal on road driving. These differences in
> > rotational speed can be
> > caused by such things as unequal tire wear or
> > different tire pressure.
> > Tire diameters should be the same within a 2 to 4
> > mm tolerance. Or, in
> > other words, if you're measuring the depths of
> > the grooves in your
> > tires, the differences should not exceed 1 to 2 mm.
> >
> > Thus people not caring tire pressure and tire
> > wear, people having
> > mounted different tire brands on the front and
> > rear axles, as well as
> > people never routinely using their spare tire so
> > it gets worn roughly
> > the same way as the other tires are most probably
> > ruining their viscous
> > coupling pretty fast.
> >
> > Removing the drive shaft as an emergency measure:
> > If you have to, and provided you're slim
> > enough, you can remove the
> > drive shaft on the bare ground (at least if
> > it's a Syncro 16"), just
> > with a little help of the factory jack. In case
> > your driveshaft was
> > balanced in its current position, it may be a
> > good idea to mark the
> > alignment points of the flanges before removal.
> > Then you'll have to use
> > a pair of 13mm wrenches (due to space constraints
> > only open wrenches are
> > usable) to remove four bolts and nuts at either
> > end of the drive shaft
> > (sometimes the nuts are only 12mm). If you
> > want to do it properly
> > you'll also have to loosen (only loosen, don't
> > remove!) the three nuts
> > and bolts (17 mm) which hold the front diff in
> > place via rubber stops,
> > so the front diff can move out of the way a bit
> > for the drive shaft to
> > be removable. However, when lying on the bare
> > ground just below the van
> > this might be hard to do. If your drive shaft
> > has got this rubber
> > element in it you may try to simply use a screw
> > driver to cautiously
> > separate the two flanges at one end of the drive
> > shaft. Knocking gently
> > at the flanges at the other end will then take the
> > drive shaft down. As
> > to the rubber element: in diesel engined and FI
> > vans the rubber element
> > was facing opposite sides. Thus you'd better
> > take some notes as to
> > whether the rubber element is at the gearbox end
> > or at the front diff
> > end.
> >
> > Replacing the viscous coupling:
> > To replace the viscous coupling you'll have
> > to pull the front
> > differential first. I don't think it's feasible
> > to replace the viscous
> > coupling right under the van with the front
> > differential in place.
>
> Derek's Note:
> 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.
>
> > In
> > particular, reassembly would thus be much more
> > difficult and would cause
> > plenty of cursing. And you'd have to drain the oil
> > first. By and large
> > there is no witchcraft involved in pulling the
> > front diff, but you
> > should do it with the van on a lifting platform
> > or above a grease-pit.
> > And it takes two people as well as a floor-jack.
> >
> > First of all losen but don't yet remove the
> > three 17mm nuts already
> > mentioned which hold the front diff in place.
> > Then remove the speedo
> > cable as well as the six screws in each of the
> > inner CV-joints. For
> > this screws you'll need either a 6mm hexagonal
> > or an 8mm multipoint
> > socket. If you haven't done it yet you should
> > now remove the drive
> > shaft as described above. If you have a
> > front diff lock (never
> > officially exported to the US) unplug it
> > electrically as well as
> > pneumatically (tag the pipes so you can't
> > confuse them later). Now
> > remove the screw holding the vent pipe of the
> > differential and then
> > remove the three 17mm nuts and bolts holding the
> > front diff. Get the
> > floor-jack in place and remove the front and
> > rear mounting brackets.
> > Then together with a second person cautiously
> > move the diff forward
> > along the skid plate and out. Look out for the
> > diff lock if there is
> > one.
> >
> > Place the front diff on your workbench in such a
> > way that the flange for
> > the drive shaft is facing upwards. You can now
> > easily remove the ten
> > 13mm bolts with which the housing of the viscous
> > coupling is attached to
> > the front diff without risking any oil leaking.
> > Lift the housing which
> > is containing the input shaft. You will now see
> > the viscous coupling
> > itself and a little spacing collar sitting on
> > top of it. Take this
> > spacing collar, grease the top rim of it and again
> > place it on the input
> > shaft in the housing and slightly press it with
> > its greased rim against
> > the bearing so it will stay there. This will
> > greatly ease reassembling
> > the diff later. Now remove the old viscous
> > coupling and put in the new
> > one. Then apply silicone sealing compound to the
> > contact flange of the
> > housing and, inserting the input shaft into the
> > viscous coupling, put
> > the housing back in place. Finally, gently
> > tighten the ten 13mm bolts
> > crosswise, applying 20 Nm (15 ft lb.), and your
> > front diff is ready to
> > be reinstalled.
> >
> > Perhaps you should use the opportunity while the
> > diff is still sitting
> > on your workbench to check what has been caught
> > by the magnet at the
> > oil drain plug.
> >
> > To reinstall the front diff in the van simply
> > reverse the steps laid out
> > above, at the very last fastening the screws
> > of the front and rear
> > mounting brackets as well as the three 17mm
> > bolts through the rubber
> > stops (apply 45 Nm (33 ft lb.) to these).
> >
> > Tools and torques needed:
> >
> > Installation of the front diff:
> > 17mm socket and ratchet, perhaps with
> > extension. Use 17mm wrench to
> > counter at the other side, 45 Nm (33 ft lb.)
> > VC housing:
> > 13mm socket with extension and ratchet, 20 Nm
> > (15 ft lb.)
> > CV-joints:
> > either 6mm hexagonal or 8mm multipoint
> > socket with extension and
> > ratchet, 35 Nm (26 ft lb.)
> > Drive shaft:
> > Two open 13mm wrenches (sometimes only 12mm for
> > the nuts), 35 Nm (26
> > ft lb.)
> > Acknowledgements:
> > Special thanks go to Wolfgang Carolsfeld in Canada
> > <wolfgang@island.net>
> > who not only proofread this text, helped me with
> > some technical English
> > terms I failed to find in my dictionary, and did
> > the math involved in
> > converting the torques from Nm to ft lb, but
> > who also successfully
> > applied the underlying German version of this text
> > to his Syncro to make
> > sure it works :-)
> > ------------------
> > ---------------------------------------------------
> > | Rainer M Woitok | Phone:
> > (+49-9131) 85-27811,-27031 |
> > | Regionales Rechenzentrum
> > | |
> > | Friedrich-Alexander-Universitaet | Fax :
> > (+49-9131) 30 29 41 |
> > | Martens-Strasse 1 | Telex: d 629
> > 755 tf erl |
> > | D-91058 Erlangen
> > | |
> > | Germany | Mail:
> > Woitok@RRZE.Uni-Erlangen.DE |
> > --------------------------
> > -------------------------------------------
|