I'm having trouble getting my rear disc brake set up on my DT build. (I've got the front working perfectly) I've worked very hard getting the caliper straight. When I adjust the inside and outside to where there is no rub, the brakes are very weak. The rub is intermittent, which makes me think the disc is not straight. I'm thinking about removing the disc and testing it to see if it perfectly flat. (or maybe I didn't mount it right)

Has anyone else had a disc that wasn't true?