> There I found many messages which seemed to show a pattern --
> that the Sachs replacement clutch from Canada is the culprit.

Actually, I think you are confusing coincidence with cause.  ALL 228mm
Sachs clutch kits sold for the last number of years have used Canadian
discs (although, as of very recently, some are now Mexican).  So yes,
everyone who has a problem with chattering has a Canadian disc.  But then
again, everyone who DOESN'T have the problem also has a Canadian disc
(assuming that they have replaced their clutch within the last several
years).  So I suspect the real cause lies elsewhere, although I'm not sure
where.

-Ron Salmon
 The Bus Depot
 http://www.busdepot.com