You might want to check out what I went through to get my 8BA "clutch geometry" to where I felt comfortable with it. There are some who said it was not necessary, but I believe that it goes a long way in explaining what might have caused the kind of mysterious problem described by "richard crow" above.
https://www.fordbarn.com/forum/showt...highlight=shim
(Please be advised that it is long and may be boring to some.)