That's interesting. In the early 70's way before all of the clutch technology, exotic lining materials, etc. and when the most radical clutch available was the Ram with the "cleaning lady" disc, we made it just fine with Hays, Zoom, Scheifer, etc. I used all of them at one time or another and behind engines with 400hp plus. Never had any of them "slip like crazy" especially when just installed. And like I said, these were just plain old asbestos lined discs.