Is this corrosion in my hub motor?

Hi ESFMs,

I'm in the process of switching bike frame and partly swapping motor core from one wheel to another.

This is a hub wheel I've have for only 8 or 9 months. Was new when I got it. When I pulled it apart, I was shocked to see white powdery residue inside the platings. I've had other motors that I've used for far longer and pulled apart before, but I've never seen this.

Should I be worried? And how did this happen?

Clinton

were you riding on the beach or anywhere near the ocean?

M

ClintBX said:

Should I be worried? And how did this happen?

Click to expand...

Yes.

Water got in somehow and stayed there. Most commonly water enters along the wires going through the axle. Once it gets inside, it is hard for it to get out and you get corrosion.

The routing of the wires going into the axle is very important. The wires should exit the motor and go downward enough to create a "drip loop", then can head off wherever they need to go.

You can seal around the wire entry with silicone, but it is hard to get between the wires.

Some people drill holes in the side plates for ventilation. This will allow moisture to escape but can also let water in.

Also see Kingfish's thread DIY Rust And Restoration

Once you get it all cleaned up (check the bearings, they may need replacement if they "catch" at all while turning by hand), you can use something like this to help prevent oxidation in the future: https://www.rustoleum.com/product-catalog/consumer-brands/stops-rust/rust-inhibitor/

It's not paint and i don't think it inhibits heat transfer too much.

Alright, that's what I thought. Thanks for pointing out the wire angle thing. I think on previous hubs, I had it angled down. But this time it was pointed up.

No, I don't ride along the beach but I do live near the river and like to commute along there. I think it has more to do with some heavy rains I've been riding in quite recently. I didn't think it would corrode that fast though. This rain only just happened last week. Other than that, for the most part I've only been in light and sporadic drizzles since I've had this motor.

There was one thing I noticed when I was unbolting the covering plate, was the ease at which they unbolted. For a first time disassembly, they were a little too easy. I didn't even hear that first time pop when just breaking the seal. I'm wondering if the manufacturer failed to seal it properly and thus allowing water to seep in.

It won't hurt to put a bead of silicone on the cover when you reinstall it. I'd guess most of the water came in along the wires though.

FWIW, you're probably better off to clean up the rust and then coat the insides per the thread I referenced, and then NOT seal the motor up, to allow it to be able to drain (or evaporate) out all the moisture that does get in.

Sealing it up is just going to trap more moisture in there, continuing the existing corrosion process. :/

Hubmotors can't be sealed completely, and are never totally waterproof. See Justin_LE's video somewhere here on the forum, youtube, and Grin Tech's site with video of his testing of such things for examples of the problem.