Bafang? 750w? motor bearing replacement

[s-petersen]

Bafang? 750w? motor?
I am repairing an e-bike for a friend, and I need to replace the wheel bearing on the cassette side. Do I need to remove the cassette? I don't see a brand name on the motor, or the size, as a mater of fact the bike was repainted, and I can't find that either. This is the closest bike I can find, but I could swear it has rear suspension, and I couldn't find any e-bikes like this that have it, also no rack, or basket.

The questions I have are, Does anyone know what motor this is?
Do need to remove the cassette to take the motor cover off?
I can get a puller for the motor cover, but if there is some kind of retainer hidden by the cassette, I don't want to break it. I will have pics of the bike next time I am over there.
I watched many YouTube vids on taking these type of motors apart, but they are all a little different, the closest I saw was the Bafang 750 as far as I could tell.

 

[amberwolf]

You'll have to remove the cassette to find out without risk of breaking things. It's easily possilbe for there to be a circlip or other retaining hardware on the outboard side of the cover bearing (some motors do, some don't).

It could even be a ridiculously complex to disassemble design that has a shoulder on the outboard side of that axle larger than the bearing ID, so it *can't* be pulled thru the cover, and instead the entire motor has to be disassembled to get the axle out and then thru that bearing, to be able to access the cover bearing and remove/replace/service it. Not very likely, but possible.

Shimano cassette, so really common cassette removal tool, though you might have to put the motor back in the wheel to get the grip on the cover to use the tool to get the cassette off. (counterclockwise, you'll probably have to use a long-arm wrench and a deadblow hammer on the far end of the wrench to start the removal, if anyone ever actually pedalled the bike it was on as it will likely be too tight to just spin off).
Probably one of these

Cassette & Freewheel

Tools to hold and remove freewheels and cassette lockrings.

www.parktool.com

like this one

FR-5.2 Cassette Lockring Tool

Designed for the removal and installation of most cassette and disc brake lockrings with a 12-spline tool fitting, including Shimano®, SRAM®, and others.

www.parktool.com

It's 12mm axle size, so it'll *probably* fit over the geared motor axle. If not, you'd have to file or drill it out larger. (I did that for a standard parktool fr-1 original version to clear 14mm+ axles; this is the current version of what I used FR-1.3 Freewheel Remover — Shimano®, Etc. ).

 

[s-petersen]

I measured the axle, and it's 15mm,the threaded part is 11mm. There are 6 magnets in the cover if that helps identify the motor, I will look into getting the tools. I ordered the tools...

 

[amberwolf]

There are 6 magnets in the cover if that helps identify the motor,

Most geared hubmotors have those, they're used to trigger the wheel speed sensor (since a typical geared hubmotor without these can't be used to measure wheelspeed, only the speed of the motor itself, unlike a DD hubmotor).

The parts of the motor casing that you don't show at all would typically have the info to identify it.

If it was not engraved in or cast into the metal (most of them are) but only painted on or a sticker, then the repainting would have obscured that info.

Beyond that, you could find out what bike it was originally, from the owner, and then look that up to see what the builder claims was installed on it.

 

[s-petersen]

My friend found it on the side of the road during junk week, the controller and wheel bearing were bad, the battery was good, it's seen a rough life, but worth bringing back, the bike was repainted, and the motor didn't have any info on it (I think) I will have to take pics if it when I go back. I tested the motor with the new controller and unsurprisingly it had a Hall sensor error, which is fine, as it wasn't connected, (waiting on a connector) but the motor worked without it.
Edit: I did find the number, I thought I didn't see it the first time, but no brand name on it.

 

[s-petersen]

I got it apart, kind of... The cassette took a little persuasion to get off, after putting the motor back in the wheel.
The cover would not come off, I had to use a gear puller, and the bearing stayed on the axle I pulled the bearing with the puller, and the outer race split, and the balls went flying. I still have to remove the inner race. The axle looks like there is a small shoulder inside the rotor, I don't see a clip, so I think I have to grind the inner race odd the axle.
There was a small clip that was on the axle that was broken already under the the clutch, I am not sure if I can replace it with a standard circlip? The outer seal seems to have the dimensions printed on it? measures close 25 25 5

 

[s-petersen]

Finally got the inner race off, that was a real pain!

 

[amberwolf]

Rusted on?

 

[s-petersen]

Ooohh yes!, bearing broke trying to remove it from the axle. There is a "c" clip that was broken in half, can I replace it with a regular circlip?

 

[amberwolf]

AFAIK whatever fits in the groove correctly and sticks up enough to keep from moving whatever the original kept from moving, it should work. I recommend a circlip wiht the holes for the removal tool, or whatever kind is easy for you to remove for later servicing if necessary.

 

[s-petersen]

The bike is back together, the hall sensor connector is not here yet, but the controller will work without it. Is there any benefit from the hall sensor? Should I install the connector when it finally gets here? This bike is not nearly as nice to ride as mine, the pedals are too close to the seat, it makes it hard to pedal. If I raise the seat enough, it's impossible to touch the ground without dismounting.
It may have more torque than my direct drive. Is there a setting P# to hide the hall sensor error ?

 

[amberwolf]

Is there any benefit from the hall sensor?

Normally a system will start better from a stop if it is sensored, with most controllers. Once up to speed, it typically doesn't matter as much, if at all.

 

[neptronix]

i'm surprised this motor could run with all that water intrusion!

 

[s-petersen]

The motor is more durable than most people would think, the windings are covered in lacquer, and only pass low voltage, so shorts are less likely.
The hall and speed sensor circuits are more sensitive, as board corrosion, and the sensor leads could corrode off. The board and sensors on this motor look pretty good, just the iron and aluminum have most of the corrosion. it is currently running without using the sensors, as I am waiting on a hall connector. it is possible when I connect the hall sensor cable there could be issues. The gears are a mix of plastic and steel, and are covered in heavy grease, so are not badly rusted. The bearing on the cassette side was destroyed by water damage though. The other bearings were fine. The motor is strong, and seems to work fine, used sensorless I have seen pics of motors that were much worse than this that were recovered.

Look at this!

 

[amberwolf]

The motor is more durable than most people would think, the windings are covered in lacquer, and only pass low voltage, so shorts are less likely.

The windings have battery voltage, PWM'd in pulses; tha'ts how these motors work.

The hall/etc wires are low voltage (typically 5v or less).