You may have a point, Bart however I'm not certain the magnetic wheel was made in China...it could have been but that's not something I can be certain of. And the temperature could have been a problem but as I recall (and this goes back many years but I could dig up the book and verify it) heat is a problem for magnetism but only when the Curie point has been exceeded. What is the Curie point? It is pretty high as I recall...around 1000 (F) is what the recesses of my mind are saying. By interesting coincidence I ruined a magnet while welding a few weeks ago. I was using one to hold two pieces together and the heat destroyed it. I'm sure you know that heating process re-aligns the molecules and turns them paramagnetic. I believe the ferromagnetic particles can be very small (like those on recording tape...which would hint at a better distribution pattern) or large (which would hint at a less uniform distribution...but only a hint). As you'd expect small particles lose their magnetism more rapidly and there will be fewer of them by definition. The fact the retaining ring is magnetized and the field is stronger at the ring's ends makes me think it was (as a friend suggested) becoming a little horseshoe magnet with the ends being the poles. It is magnetized enough that a non-magnetized screwdriver will lift it and hold it airborne...and it would not have been manufactured that way. There would be no need for it. I'm leaning toward the idea the ring has been leaching magnetism away from the wheel (hence the reason the inside part of the wheel still shows magnetism) and that loss extends down as far as the slots have been cut. Sadly I don't have a gauss meter any longer or I could measure to see if the strength declines from the top down. I do know there is no detectible magnetism where there should be. Yes, I did check the Hall Effect sensor back when I de-assembled the thing. Couldn't tell if it was ok or not, but hoping to use all the original Pertronix "stuff" I was checking it with the wheel and now that I know the wheel has lost magnetism, it doesn't matter...there would be as you know nothing to trip it. Whatever the answer if these wheels are losing their magnetism, that's got to be contributing largely to the failure of them. I still would not use one of these in any vehicle. Way too high of a failure rate. Thanks for your comments!
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
