The Syncro Drive (Prop) Shaft


The Syncro center driveshaft or Prop-shaft (located between the transaxle and the front differential) has a limited life span.   Failures are not uncommon at the 100,000 mile mark.  The U-joints have sealed needle-bearings with no provision for lubrication.  When the joints begin to develop flat or rough spots as they wear, vibration in the drive line often results.  VW does sell a rebuilt shaft.  However, the price is about $600-$800, depending where you get it. 

Syncro owners have tried various ways to avoid spending the money on a new or rebuilt drive shaft, including having a custom shaft made and attempting to rebuild the stock shaft.  Those who have gone this route have had mixed success.  It seems that at least half of the attempts result in shafts that still cause vibrations.  There are several theories as to why the rebuilds have not worked.  They include 1) use of wrong U-joints, 2) failure to replace (or use on a custom made shaft) the rubber flex disk and 3) a worn internal bearing (the end of the shaft with the rubber flex disk has allen bolts, and inside that end there is an internal shaft that extends about 6" into the outer casing of the shaft and rides on a bronze bearing that apparently can wear out and possibly cause vibration).

The first two suspected causes of vibrations after a rebuild have been addressed by use of stock VW replacement parts.  Although the VW u-joints cost a bit more than some of the others available, they are still reasonable in price relative to the cost of a new shaft.  The third possible cause of vibrations after a rebuild, a worn " inner bearing," was only recently discovered by Mark Rokus.  There has not been enough feedback from other syncro owners to determine whether these internal bearings typically wear out or are in fact the source of the problem.  Thus,  it may be worthwhile to disassemble a shaft and check on the condition of the internal O-rings, grease and bronze bearing before deciding whether to attempt a rebuild.

Details for rebuilding your stock shaft or obtaining a rebuilt VW shaft or a custom shaft are listed below.

  Rebuilding the Stock Prop-Shaft

The rebuild process itself is relatively straightforward.  1) Obtain new u-joints and flex disk, 2) install them or have a drive line shop install them, 3) have the shaft balanced at a competent drive line shop.

Parts needed:

         VW U-Joints:     251 521 000  (~$160)   [Alternative u-joints: NEAPCO 1-0321 (~$30)]
         VW Flex Disk:   251 521 001   ( ~$40)   [ BMW manual transmission disk from 1970 to 1980 will also work
                                                                           Part Number 26111106113  (~$40)].

Service needed:

Balancing by drive line shop ( ~$80)  [Some have had success without having the shaft balanced.]



Total cost:  $70 - $280+, depending on parts used and whether you do the work or have a shop do it.  Savings over rebuilt VW shaft:  $320 - $530.  It is probably advisable to have an experienced drive line shop do the rebuild unless you have the necessary tools and competence to do it yourself.

  Custom Made Shaft

One syncro owner had a custom shaft built, although he reports it is not quite as smooth as the stock shaft.
-------- Original Message --------
Subject: Re: [Syncro] syncro driveline rebuilders in
Seattle area
Date: Sat, 18 Sep 1999 23:54:15 -0700
From: "Roger  Bowman" <>
To: Mark McCulley <>,,

I also have a high mileage drive shaft with vibrations in a couple of RPM ranges.  I pulled mine out, several times, attempting to correct the problem.  I had new u-joints installed (a mistake; I would have preferred to install them myself - and I think the shop boogered the journals in one of the ends)

So I thought I would have the shaft spin balanced, which would either confirm above mentioned boogering, or show some other difficulty (i.e., bent, out of balance, out of phase with our time-space, etc.)

And no one has the fixtures to spin the VW shaft.  Facing $695-1295 for rebuilt/new drive shaft...I had one fabricated.

The new shaft has more common OTS parts, with greasable joints and a slider to adjust geometry as the different parts of the van flex.  It cost me less then $350.  It works great.

Although you might try having a local drive line shop "rebuild" the shaft, all that means is installing new u-joints.  The rubber flex collar will remain, and if that is the source of your vibration, you are stuck with it until you replace the shaft; the rubber collar is not serviced as its own part.  Try to find a shop that will spin balance/straiten etc the rebuilt unit when they are done; might save you the trouble of installing the newer unit only to have to pull it again.

And now with about 500 miles city and highway driving, all appears to be well.  The new shaft is not quite as smooth as the OEM shaft, given the absence of the rubber collar, but is smooth in operation throughout the RPM band.  So far, I am happy...

Roger Bowman - bowmanrp@

  Shop-Modified Shaft

Another Syncro owner reports finding a shop that employs a technique that seems to skirt the re-balancing problem: they cut the entire U-Joint off the of the shaft and weld new ones on, then re-balance.  His report is below:
When my driveshaft started to rumble, there were three choices:
1.used 120K driveshaft at the local VW junkyard for $100--figured it   would die soon also one for about $800

3.John Dobson at Roseville's German Auto (he works mostly on Mercedes from all over NorCal) strongly recommended, then sent it to a shop that cut off the old  u-joints and welded new, greasable ones on.  So far it's worked for another 100K miles.  $400.  He does this on Mercedes so he felt   comfortable with it.  I was too dumb to know to be worried.

From e-mail to the Vanagon List by T.N.

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