Every 4 speed gm I've worked on with diaph. was like that, the one car has been through 3 of them. Some of them not bas bad as others. Get that p.o.s out of there and put in what the Chrysler engineers. put in there. Is my 2 cents. Its not the finish, my buddys L34 70 Chevelle has been ground every time. I have done a few in my brake lathe for other apps and they were fine.

That being said, you could refinish/grind, and try another brand, I would like to try a centerforce next in the Chevelle.

If you really pay attention, Diaphragms all do it to some varying degree.


There is some bias hidden in there.


p.s. I typed this before saw the last post.