Pad's are mainly made out of a substance called polyurathane---http://en.wikipedia.org/wiki/Polyurethane And rear disk's can crack frame's, but don't always. Edit:Link didn't work, try this http://en.wikipedia.org/wiki/Polyurethane
Don't mission's have abnormal size headtubes? If so then you might aswell get a new frame, i know of absolutely no trials specific forsk's with mission size tubes.......