Date: Thu, 15 Oct 1998 10:09:25 -0400
Reply-To: Derek Drew <drew@INTERPORT.NET>
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Derek Drew <drew@INTERPORT.NET>
Subject: Syncro Diff Is Weird One Without Viscous Coupling!
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Apparently my front differential is one of 20 early 1985 front
differentials made in Austria which lacked a viscous coupling and
was made to be used with a manually engaging 4WD setup which we all
knew existed at one point. That's what the code ADK says. The ADK
series diffs are so rare, even SDP emailed me to say they never made
any, as you all saw a month ago.
The diff has a front diff lock, which is why I bought it, but now I
see that I have to go in there and transfer the viscous coupling
into it to make it function like the diffs we know of here in the
USA. Luckily it has the same final drive ratio as north American
diffs.
As many of you know, I bought this diff from Carter's Gearbox Shop a
few years ago because it had the front diff lock, after Joel pointed
out an ad for it in Hot VWs or one of those mags. I did the plumbing
for it but never had a chance to put it in. Now I am getting ready
to put it in, so I put a general query as to what the ADK series
diffs were and the answer is most unexpected.
Here are some datapoints on this diff.
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A helpful and knowledgeable person says...
A few of this differentials (only 20) were built for the
european army.
They were disigned for switchable 4WD without visco coupling.
In the rear tranny was a syncronizing hub at the main shaft, which
was
operated by a
throttle control element like the differential lock. this element
was
operated by a valve at the trim for the differential lock
operation.
This diff. and tranny was avilable only from February to July 1985.
Spare parts are not available since 1986.
The original ADK differential has no visco coupling! Instead of the
visco coupling
there is a shaft inside the front diff.. You can check it, if you
remove
the back lid of the diff. (the driveshaft side).
The ratio is 34/7. It was used only at the 78 HP carburetor model.
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Tim Smith says...
Eureka! if you tear down that diff, please try to blueprint the
solid
shaft!!!!! Send it to me FEdEx and I'll reverse engineer it into a
set of
CAD drawings. That's the missing link in my drawing set from SDP,
that and
one sliding ring that engages the 2/4WD shafts.
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A helpful person in Europe says...
>I am going to try to make my ADK unit into one with a viscous
>coupling now. So it is extremely valuable for me to hear the
pieces
>that have to be moved over from my old differential. From you I am
>now recording that I have to move at least these three pieces
over:
>
>
>1) ball bearings at the joint flange to the driveshaft
>2) pinion shaft
>3) double taper roller bearing
The double taper roller bearing is the same at both versions.
You have to change only the pinion shafts (two pieces), and the
two ball bearings of it.
And the Visco coupling too.
>Let me know if you find that I have to move any other pieces. I am
>going to see if I have the tools to remove the double taper roller
>bearing at the pinion shaft. Possibly I have the right tool in my
>collection.
You need VW 381/14 and 381/15. You can see it at the pictures.
>I am very glad to hear the news that I can still use that front
diff
>although I am not happy that there is not likely a viscous
coupling
>in it. I have *two* viscous couplings, but both of them are dead
>(need new oil). VW will not change the oil.
I´m afraid that it isn´t so easy and you need the money to buy
a new visco coupling!
If your VC´s are binding then it is not possible to refill it only.
Most of the laminary discs inside the visco coupling are damaged.
Bad oil is not the reason of the binding.
The laminary discs inside are bending when the silicon oil
heats up. The laminary discs are touching each other and then
the car is binding. I hope you can understand what I mean.
A bad VC can cause a broken pinionshaft in the
rear tranny and can also bind the power steering transmission
and cause it to go bad.
_____________________________________________________
Derek Drew New York, NY & Washington DC
ConsumerSearch
drew@interport.net
212-580-6486, 202-966-7907 (W)
212-580-4459; 202-966-0938 (H)