Got to thinking (always a dangerous process) about _why_ Triumph might have
switched to a bolt-on ring gear on the later TRactor motors. AFAIK none of
the other motors used a bolt-on ring gear, and early flywheels are not known
for being troublesome, so why the switch ? I'm guessing that it had to
change, because they wanted to replace the troublesome early starter and the
drive gear on the later starter was bigger. Given a choice of moving the
starter mounting points in the block casting, or making a different
flywheel, obviously the flywheel gets the change.
But why bolt-on ? Could it be they were worried about stocking spares for
earlier cars, and planned to offer a bolt-on ring gear that would allow the
later flywheel to be used with the early starter ?? Has anyone ever heard
or seen such a thing ?
Also, we all know that the later flywheel was heavier by about 7 pounds, but
how did it's rotational moment of inertia (which after all is what matters
in a flywheel) compare ? It was presumably a smaller outside diameter
(can't go check at the moment) because the ring gear was both smaller
outside diameter (to suit the larger starter pinion) and wider to leave room
for the bolts. Thus, the Triumph engineers may have added weight to keep
the same moment of inertia.
Factoids, comments, opinions ? Even brickbats are OK, as long as your aim
is lousy <G>
Randall
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