Stronglight arms were not particularly prone to failure. In fact they cracked much less frequently than Campy, partly because they were a bit softer and less brittle. Their greatest fault was if not installed with a thin film of grease or some kind of antiseize they could occasionally seize to the axle after many years, the downside of being a bit softer. This looks like a later crank, with more rounded arms like mod 105, rather than the earlier more square arms like mod 93. Note that this crank could be either old Stronglight 23.35 mm extractor thread or newer Campy 22.0 mm thread. Best to determine which and look for a match so you don't need two different extractors to pull the cranks.
Regards,
Jerry Moos
Big Spring, Texas, USA
> From: Rich Pinder <rpinder@usc.edu>
\r?\n> Subject: [CR] wtb... Stronglight 99 non-drive arm
\r?\n> To: "classic" <classicrendezvous@bikelist.org>
\r?\n> Date: Sunday, November 29, 2009, 8:34 PM
\r?\n> Hi all,
\r?\n>
\r?\n> I'm wondering if this is an unlikely request - are/were
\r?\n> these prone to failure perhaps ? (I can't even
\r?\n> recall how I came across the mateless part). Pics
\r?\n> below.
\r?\n> The drilled 99BIS rings are nice- i'd love to mount em up
\r?\n> on a very ugly Mondia Special that has moved into the garage
\r?\n> !!
\r?\n>
\r?\n> Arms are 170 - threads are 9/16 x 20
\r?\n>
\r?\n> http://www-hsc.usc.edu/
\r?\n>
\r?\n> Rich Pinder
\r?\n> Sherman Oaks, CA