that happened to me once but the plates didn't completely break into two pieces.. would you say poor design or bad material choice?
I just did a clutch job for a friend, 20,000 miles on a 1973 V7 Sport..
there was plenty of meat left on the friction plates but the splines were worn, like they had never been lubed? the input gear looked fine.
He admitted to holding the clutch lever in at stop lights, that cause it?
I made a special compression tool from a spare 5 speed input gear and a long bolt w/washer.. the alignment of the clutch was perfect and the tranny slipped back in place with ease!