Had nothing to do with traction. This is history in the making right here. This is the incident that convinced "Big" to make rear engine cars WORK. Don did not invent the concept but he is credited with making them successful. This was THE clutch explosion that cut the car in half, taking part of (I don't remember how much) of one foot with it.
This was at Lions if I recall. Look it up. There is plenty of documentation on this
I can still remember Don interviewed in an old magazine shortly after getting the first rear engine car to work well. Claimed he said this between him and the crew chief.
"Man the visibility is GREAT!!! Saw a big ol' 5/8 bolt down in the traps."