Flywheels

[ARGOJIM]

Ok I have a plan but am open to advice.
Have a flywheel, well actually 4, that the magnets have come loose on (some more than others).
So, who has repaired them and what did you use? How long did they last? And do machines still run and charge as of now.

Thanks, pondering.

[miller_time]

Never tried it but i was told to use super glue

[jerseybigfoot]

Ok I have a plan but am open to advice.
Have a flywheel, well actually 4, that the magnets have come loose on (some more than others).
So, who has repaired them and what did you use? How long did they last? And do machines still run and charge as of now.

Thanks, pondering.

I would use an industrial epoxy. the surfaces would have to be clean. not sure if the magnet orientation is critical. Epoxy works very well in holding scrambler clutch segment in.

[JohnF]

Loctite 331 Structural Adhesive


Loctite® 331™ Structural Adhesive is a two step acrylic, toughened, activator-cure adhesive. It is acid-free, non-corrosive to sensitive parts, fixtures in 20 seconds and develops full strength in 30 minutes. Excellent high temperature resistance. Ideal for bonding close-fitting metals and magnets.

From HERE

And:
LOCTITE 7387 Depend Activator


LOCTITE 7387 Depend® Activator is designed to initiate the cure of LOCTITE toughened acrylic adhesives such as LOCTITE 315, 383 & 384.

From HERE

But I understand that some folks have good luck with slow JB Weld. I would be concerned about heat using JB Weld.

Oh, be sure to orient the magnet polarities all in the same direction of travel.

[JoeMeg]

I just re-glued the stator magnets to the flywheel for my M18. I used JB Weld. Seems to hold just fine (plus,the magnets sorta "stick" themselves to the heavy flywheel). The orientation was N,S,N,S...... each mag has a N&S pole,just flip em the correct way. My assumption was,with the pull to the flywheel the mag's do on their own combined with the fact that the N&S poles repel ea other so they tend to "space" themselves evenly around the ID. I did not clamp them or apply any other pressure to them while the adhesive cured. By doing this and cleaning them and the stator up real nice I am seeing slightly higher voltage at low rpm's than previously realized. The M20 I'm working on now shall receive this same procedure as 4 of the 6 were loose upon disassembly.

[msafi65]

JB weld is good for exterior engine temps but softens with heat. I would look at the release point of the locktite if in the specs. Not sure what temps the original adhesive was good for but from all the magnum flywheels I've trashed it wasn't good enough. Does anybody have an idea as to temps the flywheel will reach?

[Tomo]

hi
Flywheels would run about 50-75c . At the limit of most general purpose glues .

tomo

[anotheramature]

I used JB Weld on my m20 and worked fine, just make sure orientation is correct or it wont charge, lesson well learned.

[JoeMeg]

CORRECTION Now that I think about how I "polarized" the magnets. There are two types used,each having three poles. 3 of them are N-S-N and 3 are S-N-S. they are staggered. This yields a total of 18 "poles" in a pattern as I mentioned previously N,S,N,S,N...

Very sorry if I confounded anyone by originally implying that each magnet has 1 N and 1 S pole. They each have 3.

[ARGOJIM]

Thanks fellas, 3 of my intentions were mentioned so I'll try one on each eventually, epoxy is first and jb is second, will see how I do.

[rodp]

I had cause to speak to a local adhesive / epoxy manufacturer some time ago Jim, about a special adhesive. The info he gave me was very useful and it surprised me a little.
Obviously you have to clean both parts before applying any adhesive and roughen both areas, but it's the roughening that I was out on. Apparently when the adhesive manufacturers say "roughen both areas" they have a different definition of roughen to most folk.
He was quite clear in saying for chemical bonding when they say "roughen" they don't mean go over it with 40 grit, they mean something like 2000 grit. It's supposed to end up looking like a smooth matt finish, no shine but perfectly smooth.

Hope this helps.

[ARGOJIM]

CORRECTION Now that I think about how I "polarized" the magnets. There are two types used,each having three poles. 3 of them are N-S-N and 3 are S-N-S. they are staggered. This yields a total of 18 "poles" in a pattern as I mentioned previously N,S,N,S,N...

Very sorry if I confounded anyone by originally implying that each magnet has 1 N and 1 S pole. They each have 3.

So looking at this Tec. it seems to only have 2 magnets with different polarity(not attracted) which look to be a 10 and 2 on the one with only 1 magnet loose. So I guess this is how it works on the Tec.s.

Thanks Rod, I planned on cleaning and just scuffing the surfaces.

[ARGOJIM]

Just an update, working fine since noon but smoking more than me. Gonna go a different route ad redo the tec. later.