Brake drum mic. help?

(2010-05-30 20:19:17) 1. John C Says: I'm trying to read the drum thickness on 99 pontiac sunfire DE. The max. dia. on the drum is 7.929" So I set the mic. to 7.825" and the dial indicator thing is reading -20. What does it mean? I'm confused!2. kritsada Says: You supposed to move the drum mic around the drum until you get the highest number. Try it again, if you still get "-20" then you just subtract 20 from 7.825". Seriously, you should not get any negative number if you're reading it correctly.3. joemong Says: 7.805 is your answer.unless your reading it wrong .7.845 plus .020' Tag: Brake drum mic. help?