Originally Posted by Earle
I enjoy these kinds of discussions as they tend to bring out points that some folks may not have ever considered. If someone picks up a safety tip out of it and an injury or serious car damage is avoided, it's all worth it.
Marco, I have always appreciated your inputs here and have learned and applied a lot from them - and look forward to many more of your expert contributions. But I will stand by my own "technical" observations about the original fan because I've personally been affected by these failures and have made an effort to learn as much as possible about the fan's design, construction, failure modes and causes. I certainly don't know all there is to know and, as with other things about the good old Model A, there are honest, thoughtful differences of opinion on the subject - as we see very often here.
If you're inclined to be one to defend the original fan and its continued use today, for whatever reasons, that's your choice. But the history of failures and the expense they've caused folks who've used them should be known by both the informed and the nubie-uninformed so they can make their own decision. I don't think that someone who voices that position should be accused of "spreading misinformation and B.S." We here can easily stick to the issues without denigrating the other person.
Yes, out of five million Model A's produced, it is a statistical reality that some were driven "100's of thousands of miles" with no fan troubles. That kind of statistical scatter of failure data is true of practically every mechanical part ever produced. But it's also a fact that the average car of the 30's accumulated nowhere near the number of miles, and as quickly, as modern cars. I too would like to know the failure rates of this fan in the 30's but we may never know that. However, we can see that even change-averse old Henry was forced, for some reason, to re-design the fan toward the end of production - and to a less-aerodynamically-efficient, yet more durable, design no less! Was it because of unacceptably-high failure rates in service? - or simply, as Henry was prone to do, to cut the cost of manufacturing wherever possible? I'm taking a wild guess that failures had something to do with it. Even a "few" failures back then would have quickly become a high-profile issue (as they have in spades today!) for public relations given the damage and safety implications. When someone is not lucky enough to catch a beginning crack very quickly and pull the fan, these end up not being "passive" failures.
All of the input here, I think, has been informative, useful and even entertaining. Good stuff. Gotta do more of it - but without belittling the guy who voices an unpopular or innocently-erronious view or asks that inevitable "dumb question" from time to time. I've asked my share of them. We're all gentlemen, right (to varying degrees)?
Note - I hear the reports of others who mentioned different locations for initiation of the cracks. My own experience with each of seven original fans (while trying to find just ONE I could use - back when I was uninformed about them and was overly-obsessed with "originality") was that the crack initiated at the radius where the leading edge of the blade intersected the hub. Classic fatigue failures. Two of them developed cracks within a few hours of running AFTER being certified "crack-free" by professional magnaflux inspection.
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