Factory Syncro Service Manual w/lockers

[MsTaboo]

While looking through Busmaneu's website I came across this Syncro service manual in English which has much more info than the Bentley.
Included is service for the lockers both front and rear.
And for the factory decoupler! This was a Bowden cable operated device quite different than our vacuum decouplers but shows VW had a decoupler in mind.
They label it a "Selectable 4WD" and starts at page 26.
https://busmaneurope.com/_library/_files/pdf%20files/syncro_gearbox.pdf

Pretty cool stuff I hadn't seen before, except for a brief schematic of parts.
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'90 Syncro Westy 3 knob w/Zetec

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[syncrodoka]

Thank for posting this. This information will likely be lost with time without people putting it out there and resharing it.
I have seen images before but not in english or a source.

[redriverhill]

It’s like you read my mind MsTaboo.
This is a great separate document to have.

Thanks

[ALIKA T3]

Thank you for sharing the english version

I have the french paper manual and PDF too.

At page 26 and on is indeed the decoupler, but it's vacuum actuated, which you can see on the diagrams.
The bowden cable actuation was for the PTO (power take off), and it located differently.

Here are pics I've been gathering for a while on the internet:

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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[MsTaboo]

Yep, I've heard of that PTO option also (thanks for the pictures, first I've ever seen!), but if you re-read the manual it clearly states the early factory decoupler had a Bowden cable engagement which then activated the vacuum portion of the setup. You can see the Bowden cable/knob connection at the three knob locker panel on pages 36 and 38 and where it connects to the low gear housing on page 40 with that odd vacuum setup.

(EDIT
Not sure why they thought they needed both a cable and vacuum lines?
It's a bit odd, picture 34-1792 and 34-1672 seem to contradict each other, with 34-1792 looking like our current vacuum only decoupler)

It looks like with their "Selectable 4WD" option there was no VC, only 2WD and part time 4WD as described on page 27. Note there's no VC in the diagram on page 26.

No mention of the PTO in this service manual.
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Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
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[ALIKA T3]

[tjet]

I'm trying to understand this, specifically, B.

[MsTaboo]

This was VWs idea of what is now called the "solid shaft" option that some of the hard core Syncro owners use then doing a lot of driving in sand. GW advocates this idea (they like going to Baja). However us northerners tend to prefer the AWD of the VC for snowy, icy, rainy roads.

No VC, so it's 2wd only when driving on roads and then "fixed" 4wd when selected. This binds the front diff/transmission together for instant traction on soft surfaces like sand. The slight delay in engagement of the VC sometimes causes the rear wheels to dig in before the front wheels have traction so the solid shaft idea is closer to true 4wd. It's not safe to drive on roads however with this setup, and you lose the great performance of AWD on shifting surfaces like snow covered roads that the VC provides.

Section B indicates there was automatic engagement of the coupler just by shifting into "granny" gear (cross-country gear). This is probably why the setup is so complex.
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'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
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[tjet]

I see. So they that dropped that idea as Alika mentioned. Yeah kind of a complex "auto coupler" feature, when you can just engage the coupler / decoupler (selectable 4wd) manually.

Thanks for posting this

[MsTaboo]

Yep, and the bean counters had them drop the whole idea in favor of just the VC which the majority of owners would prefer.
Obviously the engineers still liked the idea and came up with the simpler vacuum only decoupler we use today.
Too bad VW didn't continue to offer as an option.
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Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
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[tjet]

I wonder that rare PTO option uses the same gear and pieces that were originally designed for the automatic coupling feature, maybe repurposed. Hmmm.

I would guess a PTO option would be a requirement for military or some other "fleet" use, like forestry service.

Good stuff

[MsTaboo]

Looking further into this service manual it doesn't cover anything about the front locker warning system. That must have been added later.

That PTO that AlikaT3 shows seems kinda hard to use. You would need to climb under the body to attach things or need some kind of additional linkage.
I guess it could have been used for pumps or a winch? Maybe a dump truck bed option on the Sinkas?
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Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
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[syncrodoka]

The PTO was installed.for the swedish(?) market to help with sales tax.or.something like that. I have seen pictures of them and a few for sale over the years but I never got the impression that they were used for anything.

[ALIKA T3]

[MsTaboo]

Just FYI, Everett has added the manual to the Technical section, sub heading Owner's Manuals, Type 2-Bus, Owner's/Parts/Other Manuals in 1986 as a PDF.
_________________
Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
Defend democracy, support Ukraine.

[tjet]

[xclemjustinx]

Does anyone know which wires (wire colors) from the sub harness go to the locker illumination switch and reverse light switch on the Syncro Trans?

I have a 1986 Doka Syncro with a rear locker only. There has been many discussions but wanted to see if anyone here in this thread knows. Thanks!

[ALIKA T3]

[IdahoDoug]

In those days it was still common for farmers to use the PTO on their 4WDs for a variety of farm tasks. Splitting wood, pumping water into irrigation ditches, that kind of thing. Many 4wds had the "port" still on their drive trains in the form of a simple cover.

VW marketed the Syncro toward rural land owners, farmers, and commercial users in many countries. As for the tax dodge - there are a lot of examples of this. Everything from shipping pickups to the USA without beds to avoid the "chicken tax", to the Subaru Brat including seats in its bed to avoid same. It was a mess for a while. So, including a $100 PTO driven component with the Syncro probably let it be taxed with an agricultural rates break in some European countries at the time that may have been a huge discount.

The output shaft was probably a common one used by various pump shafts and the like back in the day, but something you cannot find anymore as better ways have come along to do those tasks. Cool bit of history.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Sodo]

I know a feller who’s had one for 20 years.
In a box of course, ‘cuz no need has arisen.
But if any of you folks come across a ‘need’….

Its the end of the “intermediate shaft” on the syncro low-gear housing.
The speed is 9/31 of the engine RPM.
So at 1860 RPM the output is 540 RPM.
~4mph in granny gear

Ok there ya go, who’s got a use for one?
A field mower for Van events?
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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