Blown Viscous Coupling?

[markf1]

We have been doing lot’s of work on our 1986 Syncro. Most recently very expensive transaxle rebuild and re install with new clutch and etc. You can read about all that here if desired:

https://www.thesamba.com/vw/forum/viewtopic.php?t=727120

Now I’m getting a strong sense that the VC is not working.

Forum member Sodo recommended the following test:

Here's an easy home test that gives an idea if the VC is OK.

Couple it.
Jack up the right front tire an inch off the ground.
Other 3 tires on-ground.
Neutral or any gear, it doesn't matter.
It should be very difficult to rotate the wheel slowly by hand.
It should feel like there is a component in the driveline that behaves like a stack of alternating discs with some viscous goo between them.
....a "Viscous Coupling."
Your front wheels are driven by goo.

If the raised front wheel spins rather easy, look to see if your driveshaft is turning.
If the driveshaft is turning, then you are decoupled (= 2wd).
If the driveshaft is NOT turning, then your VC is shot.

So I just did that. Not sure if it matters but it’s pretty cold out right now, single digits F. I jacked up the front right wheel and it is difficult/stiff to rotate by hand but totally doable. When turning the wheel there is a very slight amount of free turn and I can see the drive shaft rotate ever so slightly. Then it “catches/engages” and the wheel becomes difficult to rotate. It does rotate with resistance, but I can rotate,it with one hand. While rotating the wheel the drive shaft DOES NOT turn. So... sounds like blown VC. Dang x10.

Questions:

1) is there any problem driving around with blown VC? Seems like it just means we only have rear wheel drive and maybe are losing some power and fuel efficiency by having he VC turning from the drive shaft but not actually working.

2) options are do nothing, replace VC or put in de-coupler?

3) Does a de coupler replace the VC or would de-coupler still require that the VC be working properly?

TIA for any advice and guidance.
_________________
1986 Westfalia Syncro
2.1 L Waterboxer
Some Westy supported adventure photos:
https://www.openrangeimaging.com/adventure.html

[tencentlife]

I don't know how you conclude it's bad, your test shows the VC is OK. You should be able to turn the tire slowly and steadily against a constant resistance at low speed, which increases markedly if you try to turn it faster. Ambient temp has no palpable effect on this.
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[markf1]

Hi tencent and thanks for you reply.

I think it’s bad based on the test recommended by Sodo in my post above.

“If the wheel turns but the drive shaft doesn’t your VC is shot”

Maybe I’m misunderstanding. He does also say “if the raised wheel spins rather easily” which is not the case. The raised wheel spins but with significant resistance.

So the raised wheel spins but not rather easily and the drive shaft does not turn. Is this an indication one way or another if the VC is working properly or not.

Also note - We do not have a de-coupler on the van.

Thanks!
_________________
1986 Westfalia Syncro
2.1 L Waterboxer
Some Westy supported adventure photos:
https://www.openrangeimaging.com/adventure.html

[Steve Arndt]

Another test is to put 2 x 4 in front of your front tires. Like a wheel chalk. Then put a jack under the rear with the wheels of the jack inline with the vehicle. Only just barely lift the rears off the ground. Try to drive forward. If it climbs over the 2x4 you have a working VC. If you just sit there with the rears spinning in the air and no drive transferred to the fronts, bad VC.
_________________
Steve
Steve's 87 Syncro project

[markf1]

Thanks Steve. We also were given that second test instruction. In our case, we don't have a floor jack or pavement. And any pavement around us is snow covered and icy at the moment.

We are ultimately taking the van to a mechanic. He is experienced with synchros and says he can determine if the VC is working by putting it up on a lift and seeing if all the wheels turn. I don't quite understand how that would work, but he definitely knows alot more about this than I do.

So, I did the one test I could as posted above. Raise right front wheel......etc.

Still uncertain about status of our VC
_________________
1986 Westfalia Syncro
2.1 L Waterboxer
Some Westy supported adventure photos:
https://www.openrangeimaging.com/adventure.html

[crazyvwvanman]

You misunderstood what Sodo meant in the front wheel lifted test so you drew the wrong conclusion.

Read what tencent then wrote, but closely.
The wheel should turn by hand, but only slowly.
If you try to make it turn faster, it SHOULD NOT speed up much if at all.
It should get harder to turn when you try to make it spin faster.


You need a new mechanic if he really thinks he can test the VC with all 4 wheels in the air spinning.

Mark

[MarkWard]

If the rear wheels are on the ground, I'm having a hard time imagining the driveshaft between the front and rear turning when you turn one jacked up front wheel. Its been a long week.

There is no problem running the van with the VC not operating as designed, but obviously you won't have the 4wd effect.

Seems from reading most VC's seem to stiffen with age. I don't have the experience to say one way or the other.

I serviced my VC and the only test I did after was the 2x4 test. I realize you don't have a place to do that, but it sounds like you need to find a shop familiar with your unique ride and build a relationship when you can.
_________________
☮️

[tencentlife]

Sodo said this:

[markf1]

[Wildthings]

If you have both front wheels up in the air and turn one wheel the other will just turn in the other direction unless you have a differential lock that is engaged. The driveshaft will not turn. If you only have one wheel up in the air the driveshaft still isn't going to turn unless you have a decoupler. With one wheel in the air you should feel the resistance others are speaking of.

If you make a full lock turn on dry pavement it will probably feel like the brakes are lightly on if the VC is working. If the brakes feel locked or nearly so your VC is applying too much torque.

[davideric9]

[markf1]

We did the test with the floor jack. First I got her stuck backing out into the alley. It's pretty slippery out there at this pint but not glare ice. the middle zone between where the wheels of vehicles travel is also a bit soft. My 4x4 toyota was slipping around a bit but i realized I had not locked in the front hubs, duh. FWIW our subaru outback and my toyota can drive in and out of the parking/alley OK.

Once I got the van stuck GF watched wheels. Only one back tire was spinning most of time. We tested the differential locker and it definitely works and got both back wheels spinning. Front wheels never spun.

Pulled the van free with my truck and drove into underground parking garage to do the floor jack test. Reasonably flat area but broom finished concrete versus a smooth troweled surface like you might find in a shop. So more friction and rougher surface that a typical shop floor. Also borrowed floor jack was a small unit with small wheels.

Not sure any of that matters too much. Got the rear wheels jacked up off the pavement with the floor jack. Jack and jack wheels oriented same as van so it would roll correctly. Flat 2x4's on pavement in front of each front wheel. Van at idle in Granny gear, clutch out no movement, one rear wheel turning. Give it some gas, no movement, other rear wheel now spins to some extent. Engage differential lock just to further test. Both rear wheels turn same speed give more gas, van never moves. Front wheels never engage and pull van over 2x4's. It appears VC is not working correctly.

We have read that GoWesty doesn't even sell VC. They don't like them and recommend replacing with solid shaft and decoupler. Have read diverging opinions on this. We are inclined to either have ours rebuilt or replaced and get a working VC going again. We also do not think we need a decoupler. We pretty much never drive in town, generally on hiways to and from back roads.

Some questions.

1) Best to look for new VC or rebuilt VC? Or alternately maybe rebuild the one we have?

2) Is it possible to have a VC and a decoupler? Or is it such that if you add a decoupler then you must replace the VC with a solid shaft?

_________________
1986 Westfalia Syncro
2.1 L Waterboxer
Some Westy supported adventure photos:
https://www.openrangeimaging.com/adventure.html

[davideric9]

glad you figured this out. Van stuck in the snow with front wheels not spinning was your VC test. don't bother installing decoupler, and yes you can have VC and decoupler. with solid shaft a decoupler is required. new VCs are gone.
_________________
1987 Syncro Westfalia, stock (bought 1994)
1986 Syncro Westfalia SVX, 3 knob (bought 2008)
1987 Westfalia (bought 2010)
1988 Wolfsburg GL (bought 2012)

[Escorial Syncro]

I live in snow country and a syncro with a functioning VC would be my first choice. Snow conditions seem like what this rig with a VC was designed for. When a VC is working properly it makes the van a monster in snow and ice, no need to pull knobs, it seemlessly transfers power. It's a perfect simple system that just works! Plus I think the van feels more solid on the dry highway with the stock VC system comparted to driving uncoupled. But that's just my opinion. If you search this site there are many many opinions, so there is no "right" answer, just the one that works best for you.

I think if you live near the ocean and do a lot of driving on sand a decoupler/solid shaft probably makes more sense.

Also keep in mind, some decouplers do wear out, so can be another wear item. And in my experience, I think five out of the six decouplers I have installed leaked in the first year or two of service from the actuator which I found to be a bummer.

I was glad to see the OP do the VC tests on snow and then with the rear jacked up. The jack test is the most simple, most definite, the only one I trust.

Van Cafe sells rebuilt VCs. But good luck in whatever you decide.

Joel
_________________
Joel Lane
1985 Vanagon converted to syncro, ALH TDI, Reimo Primus top with Westy interior
2002 Toyota Tundra 4x4
1974 Honda CL360 Scrambler (for sale!)

[Sodo]

I agree with Escorial Syncro's opinion on the Syncro AWD system.
I drove decoupled a few times.
It was a waste of a Syncro, and a waste of the "Syncro tax".

Cool markf1, glad I was able to help
I passed on knowledge that I have gathered from lots of other Syncro enthusiasts.

And what you did markf1, was create a thread with a proper, searchable title,
then quickly and methodically, tested your VC with first the "easy home test"
then the "more definitive 2x4 chock test".
And you contributed a real-world test too, (ice in your alley), a real treat!

I bet you have helped many Syncro owners to understand their VC better,
in this one example, than years of rambling, 45-page VC threads..
Because you came at it from a novice POV, with eyes wide open.
As opposed to the "expert POV" that often confuses everyone.
....as I usually do (and sometimes myself, 'cuz I'm no expert).

It's a little funny how, once you understand the system, how simple it is.
I remember when it was a puzzlement, and the more people you asked, the more confusing it became.
Because everyone had different ideas of how it worked, it added lots of confusion.
Kinda like our society with the introduction of social media.
We have more information than ever before, yet we are more confused than ever before
by the volume, and inability to vet our sources.
We don't even care who the source is anymore.
As one sage Syncro member has in her sig-line: "the information age has morphed into the age of willful ignorance".

Don't judge too harshly a mechanic, who doesn't understand the (simple) Syncro drive system. It seems that few people do.
But a mechanic who reads THIS thread should understand it.

GoWesty, who clearly understands practically EVERYTHING about Vanagons,
won't warranty their (Syncro) transmission rebuild unless a decoupler is installed.
GoWesty further encourages the Syncro owners to drive decoupled in 2WD, to preserve the Syncro transaxle.
I don't know if I should say GoWesty doesn't understand the Syncro system, but their recommendation cannot possibly preserve the transaxle.
Decoupled in 2WD will preserve the VC, but not the transaxle.
Yall probably know my advice to GoWesty... to preserve a transaxle, focus your customers on preserving lubricity....(otherwise known as "maintenance").
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[markf1]

thanks Sodo and everyone else. I can't overstate the value of your input and advice.

I have found only 1 place to buy a rebuilt VC. German Transaxle of America. $495. Their site is odd in that you can't add the item to a shopping cart and buy it. I guess you need to call them to purchase.

I have been advised of a used one that apparently needs new seals and fluid $440. I can't seem to find anywhere to price/purchase the seals and fluid.

Our plan at this point is to get a workign VC installed and forgo a decoupler.

Thanks again!
_________________
1986 Westfalia Syncro
2.1 L Waterboxer
Some Westy supported adventure photos:
https://www.openrangeimaging.com/adventure.html

[Sodo]

German Transaxle probably wants to open up your VC first, to see if it's a rebuildable core. VCs are unobtanuim, nobody just tosses them out.

[Wildthings]

If you have a decoupler, no one is forcing anyone to use it. It is just one more option for self recovery, I like the idea of making it home so I can do repairs on my own schedule and dime verse paying some mechanic in god knows where to learn about an obscure vehicle he may never work on or even set eyes on again.

[Steve M.]

I find the decoupler worth buying for around town driving where there are tight turns into parking spaces. Seems to take a lot of stress off the front differential doing routine driving in town, but that's just my opinion.

There is some very good reading on VC's on the Tech Links of Syncro.org as well as a lot of other useful info.

http://syncro.org/how-to-fix-a-vw-syncro/
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[Steve Arndt]

I have the rebuilt "sport" VC from AA trans. Seems like it was under 500 bucks. It works great. No decoupler, and no symptoms of "sport" or drawbacks.

My original VC was a fairly stiff and aggressive one. Then it failed open with no front drive.
_________________
Steve
Steve's 87 Syncro project