In a message dated 5/15/05 9:16:28 PM, vanagonteepee@GMAIL.COM writes:

<< What ARE situations where locking the differential makes a big
difference.? >>

Whenever the van is stuck with a front wheel and a rear spinning like crazy.
Try driving on a slick road with the ass-end locked and the van will be all
over the place.

The best way to proof out a VC would be on a 4-wheel dynometer, if you can
find a shop with one.  There is a low tech VC test procedure floating around
somewhere in the electronic ether; asking about it on the Yahoo Syncro group
should provide you with more than you want to know.  There is also a spec for the
torque required to rotate the front wheel which is supposed to gauge the
condition of the VC.

A quick check to see if the VC is locking up at all is to stop the van on a
slight grade then back over a half dozen layers of polyethylene under the rear
wheels.  While heeling and toeing, ease out the clutch to determine if the
front is engaging enough to move the van.

Unfortunately, the problem with the Vanagon drivetrain is usually that a
failing VC becomes too aggressive; an aggressive VC ends up trashing the front
CV's and the transaxle.  Bad, bad design - a consumable, easily replaced part
which takes no prisoners whenever it queefs out.  It's sorta like the mafioso who
rolls over on all his minions whenever he goes down.

George