I had the dealer replace both my gearbox and flywheel ( the disc and pressure plate too since they are right there). This was done due to excessive noise from the gear box. The noise was very, very loud, and sounded as if there were marbles in the box...... The dealer got with Ford, and Ford kind of, but not really, admitted there were problems with this dual mass flywheel set up. Ford tech told the dealer to do a couple of tests to determian what was making the noise.
They were to listen to the gearbox in nuetral with the clutch out. Then to rev the car to certain rpms and note when the noise was present. Long story short, the nosie was there through out the rpm range. So, they replaced both flywheel and gear box. This was done, and they did a good job too, no problems at all. I was there, under foot , of course.
Two days later, the same noise is back, not as bad, but there. I called SVT, and they want me and the dealer to make an appointment with the Area Technical Field rep. (Not done yet)
Svt did tell me to post, and ask any one with noisey transmissions to call so they can document it.
I do remember seeing a post on here a few months ago about flywheels breaking apart and flying through the case. That post was from some one who had been "drag racing" their Focus, and "dumping" the clutch. That is the only post I recall seeing on flywheel problems.
I think there is some confusion here. Or, perhaps it is a difference in terminology. The clutch is made up of three parts. The clutch disk, the pressure plate, and the throw-out (some times called the release) bearing. The flywheel is bolted to the transmission and recieves the spinning clutch disk.
The easiest way to tell if you cluch disk is slipping is to do this: Don't to this in traffic.... Get going about 30 mph, and shift to a high gear, 4th will do, let the clutch out and floor it, look at the tach, is it reving high and your not going any place, or is it lugging down. If it is reving like crazy, then your clutch disk is slipping.