> Randall, a lightweight flywheel?
Sure. This is supposed to be a sports car after all, where performance is
more important than a smooth idle. Extra weight means it takes longer to
accelerate, and flywheels have to accelerated five times over ...
> The flywheel works by being heavy and
> creating lots of angular momentum to keep the engine running smoothly.
Actually, I suspect that's the reason the later flywheel got heavier, to
keep the same angular moment of inertia with a smaller average diameter.
BTW, I've fitted my TR3A with a much lighter flywheel (less than 1/4 the
weight of the later stock one), and it still runs plenty smooth (even
wrecked) for a sports car. If it was a Rolls Royce I might object.
> The design is bad because a direct shear force is applied by design to
> stress a joint held only by friction.
Ultimately, friction is what holds almost everything in a car together.
Nothing wrong with applying force to a friction joint, as long as the force
is always less than the friction. And since I've never heard of a TR ring
gear being spun on the flywheel (or any other car for that matter, most of
them use pressed-on ring gears), the design must be valid. Granted it's not
as strong as bolts, but as long as it's strong enough to do the job ...
BTW, there's another friction joint in this path, the starter armature is
pressed onto the shaft.
> Failure of the joint has the
> potential to be catastophic because a slip could break teeth
Seems most unlikely ... if the gear did slip, it would only do so under the
force being applied to the teeth. The gear might turn without taking the
flywheel with it, but the teeth would remain in proper mesh.
> But I would see a friction fit as
> a bad choice for the ring gear even if a failure never occurred in early
> production.
It would seem that most manufacturers disagree with you, including Triumph
on their other cars.
And as a professional engineer, I always try to resist the urge to fix what
ain't broke !
Randall
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