GNG motor noise

[ladytoast]

Hi all

Long time lurker here, thanks to everyone for a great forum, you are mostly the reason I got into ebikes and the reason I ended up going for a GNG Midmount.

And that is the reason I am posting here... I have a GNG mid mount chain drive 60V with a 48V controller, and a cell_man 50V battery (which is excellent btw).

It's just started making a very loud noise. It sounds mechanical but I've been talking to GNG and Jon thinks it might be the HALL sensor wires or an over volting to the motor (the battery typically outputs around 57 volts).

Youtube video here:
[youtube]yCjZiJ1HmxI[/youtube]

I checked the contacts of the HALL connector block with a multimeter and they seem ok.

The motor has the same power as before, it's just become (very) noisy, it's only a week old. It got a bit wet the other day but I don't think water got into the motor and I'm sure it didn't get near the controller or battery.

I am able to turn the motor over by hand with a wrench and it doesn't feel like a mechanical issue, it feels smooth enough, well the same as when I got it anyway, it's always been hard to turn by hand.

Hoping someone might be able to point me in the right direction.

Dylan

(edit: moved from General Discussion)

 

[ladytoast]

Update, i noticed this morning that if I turn the motor over by hand I can hear the same sound.

I'm really hoping it isn't the bearings on the way out already. I have been riding it off-road but it's new and had no impacts or any other abuse.

I've done lots of searching and can't find any one having this sort of problem with these motors, no mention of the bearings playing up.

It's a worry, the sound is similar to pump bearings when they go, generally an expensive repair.

Dylan

 

[speedmd]

Sounds like a bearing that went under water/rusted or the cage came apart. It could have been too dry from the factory. Could be a hall went out also. Make sure the center race is spinning on the visible bearing and check for play in the shaft. Easy to swap the bearings out. You can tell if its a rough bearing by holding a dowel /stick against the case near the bearing and other end up to your ear. You can tell which side is bad also if its a brearing quick and easy this way. No more guessing. Most any good industrial supplier / auto parts store should have the sizes. Keep us posted what you find.

 

[spinningmagnets]

Countless times a builder here at ES has disassembled a new motor only to find that one bearing had grease, and the other one didn't. Water on a clean and dry bearing results in instant rust. I don't know if that's what you have, but I wouldn't be shocked if you found that. The good news is...if that is the problem, easy and cheap to fix...

 

[ladytoast]

Thanks for the helpful replies guys.

It did rain the day before, only lightly though, I can't see how the water could have got in past the seals, but if you are correct (and I totally believe you are, I've seen your youtube video on the disassembly process) that the bearing had no grease, the water could easily get past - then this is the issue.

I'll try the stethoscope trick, hopefully it's the side closest to the motor drive side. Luckily I've got all of the tools required.... learning all the time

Dylan

 

[spinningmagnets]

Take lots of pics of the process?

 

[bee]

Sounds like my skateboard bearings after riding in the rain.

Some bearing lube should help.

 

[ladytoast]

Well after not getting any response from Jon at GNG to my emails I decided to assume the bearings were gone and to dig a little deeper.

I took quite a few pictures and put them up on my blog for anyone that might be interested. It turns out the larger drive side bearing was shot, the grease was far from ideal. The other bearing seemed ok but I swapped that out as well.

Pictures.. (youtube video is still processing)
[youtube]SaJrdmAd9Xw[/youtube]

After the repair
[youtube]D2duW7Vs0g0[/youtube]

The new Japanese bearings make all the difference, it was quite a big job though so I'm hoping these bearings last longer than 2 weeks. I took the time to add a full suspension frame to the mix as well it's a Kona Coiler and well worth the upgrade. Next I would really like to look at getting the chain drive quieter and I need to increase the size of the front brake rotor, and stop the chain falling off.

Getting there
Dylan

 

[jateureka]

Good to see you have it up and running.
Can you post some pics of it mounted to the Kona?

 

[ladytoast]

Sure. I took it offroad today, it's amazingly good fun. The frame is perfect for this bike, 100% better than the hard tail I was using before. It monsters hills, you have to hold on tight on the rocks. I am almost considering proper knobblies.



Still suffering with chain issues, but I installed a front derailleur which I am hoping with solve that issue.

Also have an issue with the crank arm hitting the freewheel on the drive side, I've take a small amount of metal out of the crank which I am hoping will solve this, but the cranks really are pretty rubbish. I'm seriously thinking about the ISIS upgrade mentioned elsewhere in the forum.

 

[E-Norco]

Hello,
can you please post the bearing sizes?
Thanks!

 

[ladytoast]

6201-RS
6203-RS

Cheers
Dylan

 

[Wishes]

Sure. I took it offroad today, it's amazingly good fun. The frame is perfect for this bike, 100% better than the hard tail I was using before. It monsters hills, you have to hold on tight on the rocks. I am almost considering proper knobblies.


Still suffering with chain issues, but I installed a front derailleur which I am hoping with solve that issue.

Also have an issue with the crank arm hitting the freewheel on the drive side, I've take a small amount of metal out of the crank which I am hoping will solve this, but the cranks really are pretty rubbish. I'm seriously thinking about the ISIS upgrade mentioned elsewhere in the forum.

These kona's really need the stock chain guides they come with, which we have to remove to fit the gng. Without them they drop chains regularly. I changed out my back cassette, removed a sprocket from it, used a spacer to offset where it sat in the back to line it up properly, then I used an elastic on the derailleur to increase the tension. That seems to be holding at a reasonable level.

Did your front derailleur help?

Wishes

 

[spinningmagnets]

Thanks for posting these videos. Is that the small cell_man/em3ev.com triangle battery? Or the larger one? Also, what city are you in? please post a link to your blog...

 

[ladytoast]

Sorry for the long delay in replying.. I'm in Sydney.

Yes that is the cellman battery, it's been really good.

Wishes, thanks for the tip about the chain guide.. I wasn't able to use the guide for the reason you stated. I think the front mech helps but when the chain does come off it's painful to get back on as it gets stuck down by the crank and underneath the motor bolts.

I'm thinking one of those new XT "clutch" rear mechs will help as it keeps more pressure on the chain, but I haven't been able to test that yet.