Thinking of buying a used M6 (2006-07). Heard gearbox reliability can be a big issue. Any experiences you can share?
I have the 6 speed...sometimes it grinds when you go from 1st to 2nd when its really cold, besides that no issues, but I only have 11k miles on my car so you can't tell much in the way of reliability from that.
Search the M5board.com E60 M5 section. There are many, many threads on SMG issues. A common current complaint is throwout bearing galling which causes all sorts of SMG actuation problems (i.e. the "bang" in the butt at slow speeds, etc). There is a recent thread there where an owner pulled the tranny himself -- clutch disc, pressure plate and flywheel were all fine, and the problem was the t/o bearing galling on the sleeve it rides on. Dealers seem to have been clueless to this problem in many cases, but it does seem to be one of the prevalent problems. The net of it is that if you do a clutch job on the V10 engine cars, make sure you replace the sleeve the t/o bearing rides on too. Anyway, searching that board will show you more than you'd ever want to know on the subject (confine search to the E60 section to narrow it down).