Flywheel Magnet Orientations and Polarity

[Beacham]

Hi there, I recently brought my 1987 Evinrude 225 (runs great) in for a tune-up and the techs wouldnt do WOT adjustment due to the fact that they noticed that three of the flywheel magnets were bunched to one side. I was quoted in excess of $2k for a fix with new flywheel. instead I spent $50 on a flywheel puller and a few magnet repair kits. I pulled the thing, removed the loose magnets, and sanded away all of the old epoxy. then I decided to remove the other magnets as well. I tapped them with a screwdriver and they popped out. great. no problemo- I am also replacing the stator, since one of the coils on the thing is blackened to bare wire.<br /><br />my questions: I took care to look at the magnet orientations before I took it all apart: three were oriented to one polarity, as marked by the little notch in the corner, and the other three were oriented the opposite polarity. as far as I can tell, someone before me did a home-made job of the same thing, since epoxy was slopped all around. (this is why I took out the three that were still attached) when I place the magnets back into the flywheel with the proper epoxy, do I place them in exactly the same orientation? that is, are the polarities supposed to alternate as you go around the flywheel, or are they divided 50/50, with three magnets on one half of the flywheel at one orientation, and three magnets at the other half the opposite? further, does the orientation matter relative to any particular point on the flywheel? <br /><br />I was planning to just glue them back in at the same orientation and polarity as I found them, but it occurred to me that the guy who did this last might have known even less about it than I do. the only complaint I have about the running of my motor has been weak charging of the battery, so I am hoping that the magnet fix and new stator will do the trick. is there anything I should watch out for in re-assembly? be sure to use locktite on the stator screws, etc? further, could I have ruined my magnets when I whacked them to get them out of the flywheel? they seem plenty magnetic still, but I am thinking of replacing them all since I have it apart. last thing, should I have it balanced?<br /><br />thanks in advance for any help, and all best regards.

 

[WillyBWright]

Re: Flywheel Magnet Orientations and Polarity

Welcome to iboats. <br /><br />In theroy, the magnets would match North to South all the way around. It shouldn't matter which way or the exact placement in relation to the pistons, just as long as they're N-S-N-S-N... I don't know who'd be able to balance the flywheel for you. Harmonics are involved. You can get even spacing by putting equally sized spacers between the magnets until the glue hardens. I have no first-hand knowledge if this is all true for this one motor, however.

 

[Dhadley]

Re: Flywheel Magnet Orientations and Polarity

The spacing is uniform between each magnet. We use bolts as spacers. You are absolutely correct that the most important thing is to get the surface clean. We've reglued hundreds of magnets and have not had a balance issue yet. The rev limiter is, at the most, at 6700 and the flywheel should remain in balance tolerances, no problem. Anything over that you'll be using a flex wheel anyway.

 

[Beacham]

Re: Flywheel Magnet Orientations and Polarity

thank you very much. in fact, the magnets are all supposed to be oriented north to south, end-to-end around the flywheel. for my particular flywheel, the spacing is 7/16ths, easily achieved with the help of six bolts. of course, this was all outlined in the instructions that came with the magnet kit, which I didnt obtain till yesterday. for some reason the last guy to glue the magnets into place oriented one half of them in one orientation, and the other half in another. it also looks like he used common, household epoxy. scraping that crap out of there was a real blast, let me tell you! I replaced all six with new magnets. <br /><br />since the flywheel was already off, I went ahead with some ignition upgrades, since the stator had one badly blackened coil that was burned to bare wire, and the powerpacks did not match and had cracks in the potting. I also replaced all six coils. am waiting for the epoxy to dry, and hope for a much smoother running motor upon restart, one that will actually charge my batteries. <br /><br /><br />SOOOO, I have cleaned everything up to the best of my abilities, but I thought I should ask; is there anything else I might want to do while the flywheel is off? I am reluctant to mess with the timing base, but figure that I should ask before I bolt everything back into place. (using threadlock, of course) thanks again in advance, this forum is really helpful!

 

[Dhadley]

Re: Flywheel Magnet Orientations and Polarity

Dont put locktight on the flywheel, crank or flywheel nut.<br /><br />As long as the timer base moves freely you're good to go. If you want to lube it, pop it off and put a drop or two of oil inside the Delron ring.

 

[Beacham]

Re: Flywheel Magnet Orientations and Polarity

..sorry, can you orient me to the timer base and delron ring? so far I have been able to just remove and replace by looking at the part numbers and getting replacements. so, with the stator removed, I am looking down at the crank, I take it. this is what I pulled the flywheel off of. instructions are to use no locktite when I replace it and tighten the flywheel nut.<br /><br />is the delron ring the donut that surrounds the crank? is the timer base the ring around that with the wires coming out?? I havent tested anything to see if it moves freely, but nothing there looks like it is supposed to rotate.<br /><br />looking up delron ring on the internet, it seems to describe a plastic ring that surrounds the timer base. I may be wrong, but I dont think that there is one on my motor.