How does the Vanagon Syncros viscous coupling work?
The viscous coupling is constructed of a series of metal plates. Half the plates, (plates 1, 3, 5, 7, etc.) are connected to the input drive shaft coming froward from the transmission. The other half of the plates (plates 2, 4, 6, 8, etc.) are connected to the front differential. These plates are enclosed in a chamber with a very unusual silicon fluid. When the rear wheels and front wheels are moving at the same speed, all the plates move at the same speed, nothing special happens, and little power is transmitted through the coupling. But, when the rear wheels begin to lose traction and spin, the plates connected to the driveshaft begin to spin faster than the plates connected to the front differential. This causes a shearing action in the silicon fluid, which almost instantly heats and thickens, becoming much more viscous. This now highly viscous fluid locks the two sets of plates together and power is transmitted to the front differential and thus the front wheels. VW says this happe
