Join Date: May 2008
Location: Royal Palm Beach, Florida
Bikes: 2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's
TG, your info on pad replacement thickness is text book.
From experience, (several times to admit being stupid), the disc pads will not wear to the Avid stated minimum thickness and still stop. At about .1mm above minimum thickness, maybe slightly less than .1mm, the spring clip, which also is a squeal device, will become your friction surface.
The bike will not stop when this spring clip is used as a brake pad. Jeanne got a wild ride as we totally blew an off camber turn on the Fandango MTB tandem, while training earlier this year. Suffice to say she was pretty irked about us going 15 or so feet off the trail before I got the bike turned back up the hill. A two minute team meeting about why we had to end our ride early did not settle well either.
In summary, if you have brake pad rub that seems to never subside, regardless of how well you adjust the pads, you might want to measure and / or replace the pads. The noise you hear is the spring clip tips "talking" to you.