Well, this explains the weird noise…

[Chris Bamford]

Less than a mile from the end of a 560 mile weekend, I heard a ‘ringing’ sound from the engine room, possibly right front. It was reminiscent of the sound of a wet fingertip circling the rim of a wine glass. Not real loud but plenty disturbing.

Turns out I could hardly have asked for an easier outcome — I have a serviceable armature on the shelf and we should be generating again soon after a good cleaning and adjustment.

Strangely, the armature and stub both spun freely in the housing; I have no idea what prompted the shaft to snap as it did.

[speedytinc]

Another "never seen this before"

[Rich Eagle]

I agree. I've never heard or seen that. I can't imagine why it would break cleanly like that.
Model T's typically do strange, unusual things don't they?

[kmatt2]

The failure at the front generator bearing could have been caused by a slight misalignment between the front generator bracket and the front mounting bracket, or between the generator main body and front mount, over a long time.

[david_dewey]

and helped along with the undercut for the bearing. I'd say you were very lucky, as if it had broken on the other side of the bearing the gear would have made a mess in the engine!

[FundyTides]

Like the old farmer said when his horse died "I don't understand it. He never did that before".

[Adam]

Slightly bent shaft that was crashing against the large timing gear and flexing slightly until it work hardened, crystalized and broke.

[Dennis_Brown]

Now repair the old armature, find a bad armature, press out both shafts and press in the replacement. I have never done it but it can be done.