Not questioning the need for shims when overall the gap is to large but I doubt it’s worth worrying over exact, precise shim thickness. When I rebuilt my transmission I went through 3 or 4 flex plates trying to find one that was straight (flat) and the mount holes were not punched over-size. None of them were flat and there was considerable run out on the ears of all of them. I finally picked the best of the lot and did my best to even up the ears as much as possible - but in the end I think there is a reason for the term “flex plate”. I actually wondered if the gap was a little excessive, if the ears couldn’t just be massaged gently to make up for it.
