Dismantling and repairing the motor :o

[jeff-jordan]

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Far more familiar than I want to be!
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Well said...
No need to hurry.

[bob2.0]

Oh dear.

Clonk clonk again.

I was giving it a test today, ride out to a nice place. I did 20 miles yesterday, 'pre-test' test, and after 30 more I felt a 'lump' when accelerating slow speed in high power.

So, 50 miles later, something happened.

I was at my destination 5 miles later and could hear 'knock knock' on the stand. Not as bad as before, but there.

Your words echoed in my ears 'maybe you need to fill the gaps'!

It did not make for a relaxing visit because I figured I needed to leave early in case I broke down and had to wait hours for recovery. But I made it home again, and it did not get worse. I kept the speed low, and stopped a lot to check the hub was not getting hot.

I don't think the new magnets have moved, with the new glue, but those old rusty ones.

So, it looks like I will get a 3rd chance to take photos for you all, how to do it!

[jeff-jordan]

Damned, damned....

I'm pretty curious what happened this time.

[bob2.0]

I think you called it right, and those gaps needed to be filled to stop this happening again. But it migth only be a bandage, not a cure.

I think this is again a case of 'OK, I tried this, and I didn't know that'.

I did notice that the magnets nearby that area seemed to be very slightly raised. I measured height above the rim with verniers, they were more than the other side. I ignored this as it was so small.

But, here is my theory now.

If a magnet starts going rusty on the back, you can tell this because the rust will swell and the magnet lifts up. This is what we've seen with the ones that were obviously rusty.

Then my 2nd repair, I left other magnets that were rusty but had not yet touched the stator.

I think all that happens if you don't fix ALL of the magnets with rust is that they will eventually swell up and touch the stator.

When you remove one that is touching, it no longer centres the rim, so the next one experiences magnetic forces and lifts to touch the stator.

Rust is not a good glue!

i.e. I have to fix EVERY magnet showing rust, because it'll be next if I don't.

I don't have to replace them, but I can reuse and reglue them so long as the magnetic field is strong and not affected.

That's why I was worried riding back, if I demagnetised more.

I might now end up trying to remove and reglue any magnets that give any hint of rust. There are quite a few! But I still have enough glue to do several.

I can only glue each other magnet slot at a time. If I were to try to glue two at the same time, next to each other, they'd flip on top of each other before the glue sets.

I will open it up again tomorrow and begin the new work. At least it is still a working motor, so I hope can be repaired again. I worry about wearing out the connectors!

[bob2.0]

I'm just reviewing photos during and after the repairs so far.

It's painfully obvious now that the magnets either side of that repaired region needed to be reglued too. At least two to the left (as in the photos above) and at least one to the right.

There are also a couple on the far side of the rim that might be suspect.

I'll take a few off and see if I can spot which ones are sound and which ones are dodgy. I guess I might break the ones that are glued on properly and not rusted. We'll find out!

I have more photos if you would like to see what I mean.

[bob2.0]

Pictures speak words;-
(updated)

[bob2.0]

All the magnets I took off were rusty.

The two on the right were the least rusted, it was not obvious but if you look at the lower picture in the last post they are from the left two slots. There is still orange rust showing on the rim.

I figured after the earlier photos of a few magnets removed (I updated them), I decided they all had to come off.

I wish I had bought the bigger bottle of glue!

I have started sanding down the slots to glue them back in.

I will put new magnets into 8 of the slots, I will match what I have done already but on the other side of the motor, for balance purposes.

Perhaps I might do more. I have enough magnets for 16 slots in total. But I worry if so many new magnets might cause the motor a problem when running?

[bob2.0]

I can now give you a full 'root cause analysis' as I see it.

The issue is that not enough glue was used. Yes, I believe this is all it was. They were saving money on glue.

I will show you that there was only just enough glue to stick the edges, leaving a gap in the middle where the rim curves.

See this example;-

WhatsApp Image 2025-04-03 at 18.33.27.jpeg (59 KiB) 293 mal betrachtet

This magnet was clean and shiny before removal on the 'outside'. There was no sign of any corrosion until it was removed.

So, what happens is that as the motor cools in a cold environment, condensation may form between the backside of the magnet and the rim (because the rim is the coldest interior surface in the motor so all the condensation collects there first).

This causes corrosion and the magnets lose 'cohesion', that is the strength between the glue and the magnet itself, because the plating that the glue is attached to just gives up.

I have tested the magnets in the slots and whether 'glued in' or just not glued, the force is barely different, it is as if once they are rusted then there is not really any glue left. They are just sitting in the motor.

Therefore, those two that were clunking in my motor simply moved!

The least rusted magnets are the ones that had the most glue. It is very simple. The glue stops water condensing and protects the magnet as an extra coating.

I think all Dayi e-Odin 2.0 motors will do the same eventually, mine was left outside by the previous owner so I have experienced it first.

The solution is to re-glue all your magnets.

If you do it before they rust, then it should stop them rusting at all.

I can't decide whether to glue the magnets the other way around, so (once I have cleaned them up) the rusty face becomes facing the stator, or whether to glue them as they were before now the plating has gone anyway and protect it with the layer of glue. My thinking is that if the damaged side (damaged plating) rust then they will touch the stator and be 'cleaned'. Or maybe they need the protection from the glue even more now.

By replacing 8 (or more) slots with the new magnets, I will have some spares so I can use the better magnets of the rest

[bob2.0]

These two slots were the best magnets, showing no obvious corrosion.

WhatsApp Image 2025-04-03 at 18.57.19.jpeg (130.64 KiB) 288 mal betrachtet

I actually dug into the metal to get them out, you can see a dent in the aluminium they were in strongly and did not 'fall out' like the others.

The reason is obvious. More glue! But it was still not spread evenly, and that gap over time would eventually lead to condensation and corrosion.

WhatsApp Image 2025-04-03 at 18.52.06.jpeg (67.32 KiB) 292 mal betrachtet

[jeff-jordan]

That's a very interesting analysis of what happened inside the motor. I guess you are right with the condensation theory.

Remember what dominik mentioned:

Magnets normaly get glued with high temperature glue, but if there gets water between the magnets and the housing, rust will grow and this will loosen the magnets.
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Very likely that they've been penny-pinching with the glue inside our motors too, so it's a good thing to know the cause and the cure.

I guess you are now ordering a new (bigger) bottle of glue .


When re-glueing all the magnets just make sure that they are clean and free of fingerprints (acetone might be your friend).
I would always put the cleaner side of them (the one without rust) into the glue (in direction of the rim), so that the sides with the remaining (or removed) rust look in direction of the stator (who will be unimpressed ).

Furthermore: the magnets that you need to replace (the broken ones and the ones that lost their flux density) can now be arranged in the way that there are always solid ones right and left of the replacement (3packs).

So, over all a good research job, that'll help one or the other of us in the future!