Bafang 250W clutch engaging noise

[viulian]

Hello,

I've got a no name e-bike (brand new) - probably assembled from kits from China. Motor is a Bafang (6 screws to open, haven't tried yet) with 36V / 10A battery. No modifications to controller, etc. The engine is on the front wheel.

It is not the first e-bike I ride - first one I rode had a similar engine, second one had a direct drive engine, and given that I am a bit on the "almost fit" range, I decided to go for a higher torque engine.

After about 30miles with it, it started to have a noise when the clutch engages.
If I coast for a bit while uphill / or start pedaling after climbing a ramp (when the bike is very slowly moving) - then I hear the noise and it doesn't sound that healthy. Clunk then grinding / scratching noise for maybe half a second, even less.

As a summary, I hear it when the engine starts (electrically) and when the torque required is maximum (bike is almost ready to stop while uphill, and I start pedaling again).

Since the engine is almost brand new (no more than 30 miles) I wonder if is normal. I don't remember hearing it on the first bike, but then I didn't have that many starts / stops on that ride as I have now in the city.

Just wanted to hear some opinions if they generally do this from the "beginning", or rarely do this, etc...

Thank you!

 

[Deleted member 4366]

Take the side off, then clean and grease the rollers in the clutch. It sounds like one is sticking.

 

[viulian]

I've been trying to figure out how to take everything apart ... watched some videos - very few "tutorials" out there mostly photos with broken nylon gears.

Here's how the engine looks from outside:

I guess the first step should be taking the wheel off - then I will have access to the side plate (on the right of the bike, the one pictured above).
Then after I open the six screws I will be able to just take the side out ? Any magnets involved in this step ?
Also, is the clutch on this side too - or is it on the opposite side and I would have to take the engine apart completely to get to it ?

Sorry for the beginner questions I don't want to break it ...

 

[Deleted member 4366]

After you remove the 6 screws, you tap the axle with a soft mallet or a big hammer and a wooden block, then the whole core of the motor comes out attached to the side-plate. The clutch should be on the open side for easy access. They're normally a tightish fit on the shaft with a key-way to stop them turning.

 

[viulian]

Thank you for the reply. I understand now how to proceed .. and when initially you told me that the clutch roller might get stuck - I was wondering how come its possible to have a new engine which is not properly oiled.
However, after another week or so, I notice that the engine is a tad noisier than in the beginning (it doesn't sound that smooth anymore, but more rugged sound, like indeed, lacking lubricants).

I will sort it out in the weekend and post photos.

Will silicone grease work work ? (I have it in a spray can, to be used for the o-rings of my aquarium filters) or do I need some car engine grease ?

 

[amigafan2003]

Silicone grease is perfect for motors.

 

[viulian]

I have decided for now not to open it ... although it is very tempting, the bike is still under warranty and I started to notice few more problems:

a) when the engine gets hot (after let's say 3-4km) and I'm climbing a moderate hill - there is an occasional stall (bike looses power for one half a second, one second) as the engine stops. It recovers very quickly, but when it was new, I did not notice this - but yesterday it did it twice during the ride.

b) it became more noisier and hotter to the touch after a 5km ride. Also, after it gets hot, it tends not to pull that better (which I understand as a loss of efficiency as temperature rise inside). But in the beginning it didn't seem that sensitive.

c) I still have the clutch engaging noise, but I have started to pay more attention not to start pedaling fast when bike is slow.

So for now I have decided to wait few more months just to see how it evolves and probably I will call the warranty first given that problems keep adding up.
I have read more about opening the engine, some are easy to take apart, some are more difficult, and for now it seems under control.

The engine is a Bafang Swxb just from looking at engine photos online.

 

[Deleted member 4366]

The motor cutting out is not a problem in the motor. Instead, it'll be something in the control system. Here's some causes in likeliness order:

1. The battery BMS is cutting the battery because you've gone below a minimum cell voltage. This tends to happen at full power when your battery isn't fully charged. If it does it less when you start off than when you've done a lot of miles, this will be the cause. It could also happen with the BMS over-current protection if your battery is under-rated for the controller's maximum amps.

2. The temperature sensor in the controller has detected that the controller is too hot. This normally happens after climbing very long steep hills.The controller will be very hot to touch.

3. Speed limit cut-off. Some bikes have a very abrupt cut-off at 15mph. When your speed gets back down again, power cuts back in, so it feels like an electrical problem. If your bike has a LCD panel, you have a good chance of being able to release the speed limit for smoother operation.

4. Connection fault between the controller and motor. This problem normally shows as juddering that feels like a mechanical problem in the motor, but is only a connection fault. The motor connectors carry a lot of current, and it's not uncommon for them to get quite hot. The heat can affect the connectivity, so that the cutting happens more or less after the motor's worked hard for a bit. i'd expect a bit of juddering before cutting out if the fault is on a phase wire, but a faulty hall connection could cause random cut-outs, but they tend not to re-connect after a short rest.