Didn't Bell's K-Flex design (OH58/206) work on a similar concept to the S92 coupling, no fretting or rubbing...
I could be wrong, but I was under the impression that each K-Flex flexure has an infinate working life as well. They are/were a great improvement on the older grease filled flex couplings.
Are the above couplings a true constant velocity or do they also suffer a slight change in speed per revolution as do UJ's?
