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RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 02 2021 10:36am
by ccgarnaal
So I managed to kill a RH212 motor from grin.
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I recently build an electric bullit. (My second e cargo, first one on 2 wheels)
And as I have some more disposable income I did not skip on parts.
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Bullit frame, Alex rims.
Magura mt5 hydraulic disc brakes
72V 34Ah battery, with samsung cells.
Grin RH 212 kit with phaserunner controller, torque sensor, cycleanalist etc.

I've been driving for a month, with a temporary wooden box. ( box extendable in width, prototype)
I want to build a carbon fiber box if this extendable box idea works out.

I hit a large pothole at 35kmh unloaded. (35kg bike, 70kg me, 10kg cargo)
And the hubmotor just split in 2. No rim damage, no broken spokes. (Spokes have been teared out of the motor)

Impressive wheelbuild quality by grin. Motor casting not soo much.

Re: RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 02 2021 11:02am
by RTLSHIP
that looks like a massive earthquake fault or crack. I don't think any kind of epoxy will fix it as the cover has to support spokes. It looks like the bike is tough work to make turns.

Re: RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 02 2021 11:13am
by ccgarnaal
RTLSHIP wrote:
Apr 02 2021 11:02am
that looks like a massive earthquake fault or crack. I don't think any kind of epoxy will fix it as the cover has to support spokes. It looks like the bike is tough work to make turns.
Yeah, not going to fix this. I can weld aluminium. but even then. I would need to clean up the threads too. And the risidual welding stress is not great either.

Bulllits drive very well, they are some of the nicest 2 wheel cargo bikes around. You can make tight turns with them and lean in like a normal bike. You just need to keep a little weight on the front wheel. That is why I put the battery there.

Re: RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 02 2021 1:24pm
by RTLSHIP
Ask the vendor if they will sell you a replacement cover. Any respectable vendor will try to work with you assuming the hub was not
abused or overweight. Those hubs/covers should have some kind of ratings or specs so that you know what to do and not do.

Re: RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 07 2021 12:58pm
by ccgarnaal
UPDATE:
Grin is sending a new motor in warranty.
It has apparently happened before with 9C motors, but some years ago.

Re: RH 212 hubmotor split in 2 on my new build e bullit

Posted: Apr 08 2021 6:58am
by RTLSHIP
ccgarnaal wrote:
Apr 07 2021 12:58pm
UPDATE:
Grin is sending a new motor in warranty.
It has apparently happened before with 9C motors, but some years ago.
It is possible that this aluminum had bubble or pocket inside and that under fatigue it just gave out.