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AntonLargiader AntonLargiader is offline
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Join Date: Apr 2007
Location: Charlottesville, VA
Posts: 471
The two that BMW sells (crapshoot under the same part number) are 17-ball and 19-ball. Most of them from the factory were 19 ball but I have seen an original 17. For a while (a year or so ago) they were coming as 17-ball versions and lots of people thought that was the holy grail of FD bearings, but then they went away and it was just the 19 again. The last ones I've bought have been 19. No big deal IMO; I think either will last just fine if the FD is shimmed properly. Most that I see are too tight.

AFAIK the movement is a function of the fit (C3 for most of these) so it seems a 21-ball C3 would not have a more precise fit. And I don't think the precision of the fit is an issue anyway.

The prevailing thought was that the 17-ball had deeper races and was therefore more able to resist lateral loads. Haven't measured that myself but I am working on two of them today so maybe I can get that info.
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Anton Largiader
Charlottesville, VA
Old 07-04-2007, 04:08 AM
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