I REALLY would not get too excited about min thickness on those girls. They have LOTS of meat and the pistons have lots of travel. You could easily DOUBLE the allowable cut and still be very, very safe. I have turned hundreds, if not thousands of drums and rotors in a previous life, all the way from little Fiats to over the road truck trailers. And I've relined shoes, and trailer brake shoes, and quite a few winch drums and such.