How to you determine if the viscous coupling in the Syncro drivetrain is
freewheeling when it should be ?

On a normal syncro van when you lift only one front wheel will it  spin
freely if you turn it slowly enough ( < 18 ft/lbs) ?

I have a hunch that ours has been frozen in the engaged condition, even
before we bought the van 18 months ago. I've found reference in the
archives to testing the engage point by lifting one wheel and turning the
wheel with a torque wrench to find the point where resistance indicates
engaged  viscous coupling. So does this infer freewheeling at lower turning
moments ?

Our 87 Syncro developed a serious front C/V joint tick after I foolishly
tourqed the wheels to final tightness, wheel up, one wheel at a time, while
rotating tires (never monkey wrench with only 4 hours of sleep!). With the
handbrake applied, wheel blocks etc. the rear wheels obviously wouldn't
turn but in retrospect I think the front ones should have.

To try to isolate the C/V joint ticking sound I removed the rear > front
drive shaft. The rear flange of the front differential (still installed
with front axles in place) has about 1/8 in. radial play, but won't rotated
freely by hand. Does anyone know if it should rotate ?

Now that I've driven without the main driveshaft, I've noticed considerably
easier parking turns on pavement, less tire abrasion sounds in slow tight
turns, and lighter steering on the road. With no prior Syncro driving
experience when we bought the van, I think we accepted the handling
properties of a vehicle with fulltime allwheel drive due to a frozen
viscous coupling.

I'd appreciate any tips anyone could offer on determining the operating
condition of the viscous coupling while installed. The local dealer seems
to have no experience replacing  them and doubts that they can fail in a
linked/latched condition. Also claims that VW Canada hasn't sold any
replacements yet, but I haven't heard their price yet either !

Wolfgang Carolsfeld
carlsfld@island.net