Graphic shots here from the Wikipedia entry on viscous coupling. I think they were supplied by some English chap who cut open a failed unit. Note the colour of the fluid, I wonder if this colour is due to old age break down, metal particles, or its the stock colour for the polymethylsiloxane and any additive the maker adds. The plates have either notches on the outside (engage with VC housing and flange shaft), or on the inside (engages with pinion shaft). The piercings on the plates are there to reduce heat induced warping. I think its the tiny burrs produced when those plates are pierced that are referred to in the abstract posted previously.