Motor Bearing Removal

[awol]

Any idea how to get the bearings out of a Bafang CST motor ratchet part? My inside one I'm pointing at had seized which I've now got turning but it feels like it's got sand paper in there.
I've tried pressing them out with a socket and vice which has loosened a spacer between the 2 bearings but don't want to damage the outer body part pressing unnecessarily hard.

 

[Deleted member 4366]

Try heating it up with a hot air gun while it's in the vice.

I think that there might be two bearings - one either side of the spacer. There's definitely three things in there, so maybe there's shoulders under the spacer and each bearing comes out the end it's located, in which case getting them out will be tricky.

Edit: Just checked.

I'm pretty sure it is two bearings. You can push the spacer to the side and tap the bearing out with a drift. You need to heat up the hub first.

 

[Nealh]

The free hub body bearings are IIRC are loose ones on the outer and race type on the inner body.
Show 2 more clear pics or the free hub body looking down into both ends. The inner one you are pointing to is either a sealed/pressed fixed bearing or might well will be held by a lock ring or circlip. Poss if a lock the lock ring might need a special tool to undo ?

 

[Deleted member 4366]

I just cleared the grease from mine. Definitely two bearings that look identical and they both go out the way you're pushing because there's a shoulder on the inner end. Don't lose the shims. There's one on each end.

There's grease all over the keyboard now!

I had it at the back of my mind that you had a MXUS motor. Is this the one that's done 14000 miles?

 

[awol]

Bingo !!!
Thanks both for the help. Both spot on.
Pressing as I did would never have done it as a circlip was holding the inside bearing in place but loosened the spacer enough to move it to the side and get a pin-punch down to the outer bearing and after warming the body it tapped out, then removed circlip and the inner bearing taps out no problem.

For reference, the bearings are 6902RS 15x28x7

d8veh, my MXUS I've done thousands with it, it's on my leasure bike at the moment which hopefully next year will be my summer commuter, this CST is off my current commuter as the winter weather gives it a bit of abuse and this has higher torque against the headwinds. I've done thousands of miles on both really.
I'm going to change all the bearings inside the motor too so will no doubt be back soon for more help with those.
Sorry about the keyboard, I've got grease all over my mouse and phone now.

 

[awol]

Don't lose the shims. There's one on each end.

Oops, I can only find one, that brass one in the top photo.
Any idea where I can get some spares?

 

[Deleted member 4366]

Oops, I can only find one, that brass one in the top photo.
Any idea where I can get some spares?

Like the circlip that retains the inner bearing, the outer shim isn't needed because the threaded piece screws all the way to the bearing. You only need the shim that's shown in your first photo. Is the outer one stuck to the bearing?

 

[awol]

Like the circlip that retains the inner bearing, the outer shim isn't needed because the threaded piece screws all the way to the bearing. You only need the shim that's shown in your first photo. Is the outer one stuck to the bearing?

I've just discovered a second brass shim on the motor shaft, so there must have been 2 shims between the inner bearing & shaft shoulder, so shouid I put one on the outside between the outer bearing & locknut when I re-assemble?

 

[Nealh]

Excellent awol one to refer back to for future reference. Hope it all goes back ok, the awkward bit is the circlip and spacer in the way.

 

[Nealh]

I do seem to remember D8ve saying that on the hub motor side plate two puts extra side pressure on the bearing causing failure so possibly could be the same with the free hub

 

[awol]

Got this inner bearing out simply by screwing some M5 bolts through from the outside of the sideplate to push it out.
This one too is all rusted/gunked up and grinds round.
It is a 6811 RS 55x72x9

 

[Nealh]

Different side plate and bearing to the BPM then as the BPM uses a 6002RS. Water has obviously got in to penetrate the bearings and help cause failure might be worth trying to seat it in some (water resistant) white grease on both sides and in the free hub assembly.

 

[Deleted member 4366]

Water gets down the back of the cassette hub. It's not easy to seal there.

Regarding the shims. I can't say what's best. I think my motors have one on the shaft as well as one stuck to the bearing, so I'd leave as is. The shim on the outside is completely unnecessary because it doesn't shim anything. It's just acting as a washer, but you don't need a washer either.

 

[awol]

And lastly this non-drive side bearing taps out easily using the socket idea I got from this forum.

This one is a 6904RS 20x37x9 and still spins smooth but since I'm changing the others I will change it anyway.

 

[awol]

Finally got around to reassembling the motor with new smooth bearings thanks to GAPbearings (ebay). My first attempt at tapping them in failed since I could not get them straight enough, so made a bearing pressing tool out of a large bolt and steel discs thanks to D8veh for that tip in a past thread.
I only hope I replaced the shims etc all in the correct order and blobbed enough grease in the correct places.
The motor is now sooo smooth and quiet, in fact better than new I would say for a total cost of about £20

 

[awol]

And Continuing....
While the above motor was in bits I used my spare bafang CST (same type of motor) which was new and unused in my garage for a couple of years. After only about 500 miles or so I got a grinding-bearing type noise - only when power was applied.
Today I opened that one and found moisture must have got in, white chalk type compound inside, along with a siezed bearing. See the white powder and the rust leaving the bearing in this photo.

Luckily I had previously ordered extra bearings last time so bearing changed, housing grease cleaned out and replaced and reassembled, all in one afternoon. Will fit and give that motor a test ride tomorrow.

 

[soundwave]

 

[awol]

Wasn't that bearing causing the noise, so tried a spare clutch plate but wasn't that either. This meant it must be from inside the actual centre motor part itself, think it's called the stator.
This was not easy to seperate the part with the electronics&magnets from the outer spinning housing but when I eventually pulled them apart there was rust inside on a couple of magnets like in the above video. Cleaned it all up with WD40, reassembled and now it's smooth and quiet again. Cost - 1 headache