Bearing always breaking on 6384 motor

Build, Repair & Mod
1

Hello efoil experts,

I have recently been able to test my efoil on the water. Good news is its flying but bad news is the 6800 bearing at the top of the stator is breaking extremely quickly. I did only 2 sessions of ~40 min and it broke each time :cry: !!!

Here is the broken bearing :cry: ( motor is not waterproofed, it has only been sank in CRC 6-66 then rinced in fresh water after each session but seems not enough)
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I am wondering what is causind such quick failure:

  • Is it because of the shape of the base of the shaft that is pushing direcly on the bearing, I forgot to put a washer betwen it and the bearing to spread the axial load ?

    image
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  • Is it because of weak bearing : I directly change the original bearings with these one
    https://www.aliexpress.com/item/4000201499767.html?spm=a2g0o.order_list.order_list_main.21.23325e5bb0SaAi
    Strange the other 6800 bearing on the other side is not breaking

  • Is it because the propeller I printed in PLA is unbalanced ?Tthe print has little imperfections, also I covered it of epoxy to strengthen it. Propeller is light so could it break the bearing so fast ?

  • Is it because I missing some pieces in the motor. Here they are:

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    image367×647 33.3 KB

But I have still a small gap:
image

By the way do you know where to buy the “golden ring”
image

  • Is it because there is a direction/way to insert the bearing to better support axial load ? I can see from the destroyed bearing that it is not symetrical:
    image

I am really lost. Could you please help me to solve this issue :pray:
Thanks in advance

1 Like
2

Hard to tell, unbalanced propeller is not good but it should not kill the bearing in such a short time. I use a 63100 motor with stainless steel bearings and a Flite prop. The bearings last around 500km. That is what to expect because of the axial load through the propeller, best would be to use angular contact bearings but there isn’t any available that fit.
I also tried hybrid Stainless/ceramic bearings but they did not last long.
These are the bearings I use.

1 Like
3

Are you riding in salt water? Does the water have suspended particles like sand in it? (I’ve noticed sand getting into my motor when the ocean’s really churning and clogging up my motor which required a disassembly before I got out onto the water.

I don’t think it was rust because these failed so quickly. Unless you previously splashed the motor for a test? Ultimately, both of these would show when you disassembled the bearing. Is there rust?

Can you describe how the failure felt while you were riding? Was it instantaneous, did you gradually lose power, did you hear any sounds?

Do you have another unmodified motor to compare your current motor to? This can help you out with the exact spacing that you need, what it should feel like when you spin it, surface conditions, etc. It’s useful to have a good ‘golden’ unit to compare your current model to.

Ultimately, I think this is your issue:

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image1748×944 111 KB

These bearings are for light load, low speed, per your link.

Look for a set of bearings that are working in the field, there’s plenty linked around the site here.

Good luck!

1 Like
4

The JZN stainless steel bearing from AliExpress exploded during the second session. Looking for an alternative

1 Like
5

Oh, just changed mine on 6384, had one short but successful session so far on them.
Was it the link you posted before during BF?

6

Yes, that link, sorry for that. I used these without problems for a while, but to my friend on the waterproof 6374 it broke on the second session…
From now on I will buy either on kugellager or from a reputable brand such as NSK or EZO