Cracked 9C Side Cover

[themadhatter106]

I have a little over 9,000 miles on my motor and have been hearing a clicking sound coming from my rear wheel which was most loud when peddling but also noticeable when coasting. I was checking the wheel bearings, replacing the freewheel and none of it helped. When investigating yet another time I just happened to notice a crack all around where the bearing sits on the freewheel side of my side cover. When I put some oil on the crack and tested it again the click was gone. So this is definitely the source of that clicking noise.



I also noticed the beginnings of a crack in the same area except on the other side cover. Arrrggg!!! Two new 9c side covers from ebikes.ca is more than half the price of a whole new rear motor and I'm out of the warranty period. They really should make some steel side covers so the crappy beer can aluminum they use doesn't fail from fatigue. Do I have any other options?

 

[Punx0r]

You could get them welded up, but paying someone to do so will probably cost more than a replacement cover. That's assuming the metal will readily weld...

The cause of the crack will be the design (stress raiser and/or a problem with the alloy used.

 

[themadhatter106]

Hmm... I wonder if anyone else has tried to weld their cover back together rather than replacing it? I don't think that it would be more expensive than buying a new cover since I've gotten small aluminum welding jobs done around here for about $20. Hopefully someone else has tried this and can offer some insight.

Right now I hope that I can actually secure new side covers for my motor since I just realized that the ones on ebikes.ca are the wrong ones for my motor. They are for the newer 9C motors they have been selling with the freewheel plate being curved and the disc side being flat. My motor is the opposite, the freewheel plate is flat. Additionally, the wires on my motor come out of the disc brake side instead of the freewheel side like the newer 9C motors Grin has been selling. I sent them an email so hopefully they will still have some of the older Side Plates lying around they can sell me.

I was also looking at this as a backup:
http://www.ebikekit.com/kit-components/wheel-parts/hub-motors/rear-500w-direct-drive-motor/

I'm not positive that the plates on this 9C type motor will be the right replacement for my current side plates but the wire is coming out the freewheel side and the disc side plate has the bulge so it is at least the same in that respect.

 

[motomech]

That cover is cast Alum., very hard to weld.
I've seen replacement covers at reasonable costs, Cycle 9 maybe.

 

[hungarianguy]

The same happened to me! I've tried to get it welded, but didn't work, after a few days it was broken again and btw it was pretty expensive

Finally I found a used side cover very cheap in a ebike service. The side cover I found was not from a same type of motor, but it's diameter was the same, so I ordered it and now, after a bit of facing it works great.

 

[themadhatter106]

I was able to fix the problem so I figured I would update this thread and post some pics since this method of failure is not uncommon for hub motors. Even some of the newer Crystalytes HS series motors are cracking in the exact same spot. As more old 9C motors go into high mileage as mine has they are bound to crack. Here are some better pictures to show the cracks which developed on both of my 9C side covers.




Here is Justin's dimensional diagram of my motor: View attachment 4

It was a real PITA to find replacement side covers. I wasted about a week emailing back and forth this guy who was not Justin at ebikes.ca sending him pictures and waiting for him to reply (he was quite slow). I was getting pissed because I had sent pictures and told them when I bought the motor from them but it was taking a long time for a yes or no answer on whether they had my side covers. Finally Justin chimed in and sent me two pictures on what they have and they only have the disc cover for me not the freewheel cover. It was my freewheel side that was cracked the worst. They also discontinued stocking the 9C motors so they aren't going to be a future source for 9C parts.

Then I turned to ebikekit.com they are much closer to where I live and since they sell 9C clones I asked if they had any extra covers they could send me. They said that they did have some extras and they could send them to me (only pay shipping!) but they weren't entirely sure they would fit my motor. I compared some measurements they gave me and I was pretty confident. When I received the side covers there was one problem. They sent me two side covers but they were two side covers for the freewheel side. I'm not sure why they sent me two for the same side since I told them both of my motor covers are cracked and I only have one motor. Anyway, they sent me the disc side cover when I told them this.

There are some small differences between the 2011 Grin 9C and ebikekit.com covers. Here are some pictures I took.

Freewheel Side:


Disc Side:
View attachment 2


What I found was that the freewheel cover was a direct bolt on replacement for the 9C cover. The hole pattern is the same, the only difference is the curved edge on the cover verses the sharp edge on the old one. However, the hole pattern on the disc side was different than my cover. Oddly enough the hole pattern is not the same on the ebikekit disc and freewheel side covers. I was able to re drill the holes using my disc side cover as a template. After I did that it went on fine and the motor worked with no more creaking noises from the covers.



All in all it took about 3 weeks to locate both of the covers and install them. Most of the time was spent waiting for people to reply to emails and see if they have what I was looking for. Hopefully some day they will not make hub motors which have this weakness.