Change bearing from motor shaft, how?

[m4x]

Hi

I've just unscrewed my bafang mid center motor and found that a faulty bearing is causing a loud noise when the engine is assisting with power to my ride.

Before I do anything by myself, how easy/hard is it to change it? Is there any special tools needed? Or should I let a workshop do this job?

Here comes the bearing:

 

[J.R.]

Hi

I've just unscrewed my bafang mid center motor and found that a faulty bearing is causing a loud noise when the engine is assisting with power to my ride.

Before I do anything by myself, how easy/hard is it to change it? Is there any special tools needed? Or should I let a workshop do this job?

Here comes the bearing:
View attachment 89255

Some bearings are press fit, some can be removed by hand. The former requires a bearing puller.



If the diameter is between 17 and 38mm this one should work:

https://www.amazon.com/dp/B01FC921EQ/ref=cm_sw_r_cp_apa_glt_fabc_MWC598ZQ46WA9RDY42R7?_encoding=UTF8&psc=1

There are others available for a variety of size bearings.

 

[m4x]

Hi
Perfect, that was a great tool indeed! The diameter is 24mm so it should fit without problem.

How about installation of the new one? Just use a rubber hammer?

 

[indianajo]

If it is fairly easy, a rubber hammer is fine.
If it is really tight, then pushing on the center tube is safer than pushing on the outside. I use 12 point sockets as bearing installers. Use the smallest size that will fit. Beat on the socket with the hammer, or hydraulic bearing press. Don't go undersize and dent the shaft. The socket should slide easily over the shaft before you put the bearing under it.
Industrial grade bearings may last longer than ****ese bicycle garbage. I found my ebikeling motor had a standard 6003, which was available in a sealed bearing by SKF from mscdirect.com . Turned out made in Argentina. I've used 6003 from taiwan as a quill bearing in my lawnmower, to cut 30" tall johnson grass @ 2400 rpm. Now no longer available by evercool via oreillys.

 

[retiredNH]

If you're not sure what you're doing, have a shop do it. It's all too easy to put on a bearing improperly, either damaging the bearing on install or not having it aligned properly. This will compromise bearing life. I agree though, that, in places that are hard to lube and have a hard service life, like a bike motor, a sealed bearing is the way to go.

 

[AHicks]

I would pop the motor shaft into the freezer for a while (overnight?), and warm the bearing with a hair dryer. That should make for a pretty easy install. Just don't use a metal hammer on the bearing!

 

[m4x]

Thanks guys, I have found a workshop that will pressfit the new bearing properly. However, they didn't have any tools to pull it out..

The room underneath the bearing is only 1mm. Of all the bearing tools out there, I have only found 1 that have 1,5mm jaw thickness which will not fit in between. It seems I have to do it in another way. Any ideas?

 

[J.R.]

That gap is 1mm? If the diameter is 24mm, the depth of the cartridge has to be at least 8mm, the gap looks more than 1mm. Pullers work on the outer edge of the cartridge, not on the black seal or the inner race near the center hole. Pictures can be deceiving though, but it sure looks like a bigger gap.

There are ways to heat up bearing cartridges to remove them, but I wouldn't do it on that. Try a local machine shop. You can also try companies that service power tools. I've dealt with a company that sells and services tools like routers, drill presses and table saws. They service bearings everyday and work on tools of similar size. I had bearings replaced on a shaper table that looked to be a similar size setup.

 

[m4x]

Yes the gap is 1mm surprisingly, I have measured it a several times now. Pullers jaws won't fit underneath due to its thickness (where you have marked with a red dot)

Thanks for your advice, I will contact some local machine shops to see if they can help me.

 

[J.R.]

Yes the gap is 1mm surprisingly, I have measured it a several times now. Pullers jaws won't fit underneath due to its thickness (where you have marked with a red dot)

Thanks for your advice, I will contact some local machine shops to see if they can help me.

Ideally the person removing the old cartridge should be the same person installing the new cartridge bearing.

Having dealt with commercial, industrial and personal machines for decades I've done business with some great local machine shops. They not only can remove and install bearings, they also can spec and source quality replacements. Its difficult for the average end user to know the difference between a quality cartridge bearing, that will hold up for it's intended use and junk bearings made from poor steel. A good shop will take into account RPM and load ranges to spec a proper replacement. Size does matter, but so does quality. You don't want to go through all this again a month or so down the road.

 

[m4x]

It would be ideal if the same person do all the job, that is what I hope to find.

I have already bought a replacement bearing: CODEX EXTREME 628 2RS C3 P6Z3V3 / RLQ2 (what will be replaced on the picture)

Also have a second bearing on the same shaft on the other side (not seen in the picture) that will be replaced with SKF 16002-2Z. Hopefully the both replacements will let the center motor live a troublefree life.

Both bearings were recommended by a onlineshop (just selling bearings) after giving them all the details printed on the current ones.

 

[retiredNH]

It would be ideal if the same person do all the job, that is what I hope to find.

I have already bought a replacement bearing: CODEX EXTREME 628 2RS C3 P6Z3V3 / RLQ2 (what will be replaced on the picture)

Also have a second bearing on the same shaft on the other side (not seen in the picture) that will be replaced with SKF 16002-2Z. Hopefully the both replacements will let the center motor live a troublefree life.

Both bearings were recommended by a onlineshop (just selling bearings) after giving them all the details printed on the current ones.

An online shop will just tell you what fits, not what's a quality bearing.

I second J.R.'s suggestion regarding finding a shop that will do removal and install. Bearings can be tricky. You can damage the motor during removal. You can improperly install a bearing pretty easily such that it fails prematurely, perhaps catastrophically. But with a quality bearing properly installed, they can last what seems like forever.

I did bearing replacement in my youth. Generator bearings (yea, that long ago) that were designed to be easily replaced, wheel bearings that seemed to be designed not to be replaced (and were self-aligning), bearings on tools and such, but these days of sealed bearings, while they last much longer, are often trickier to replace.

Good luck. Strange how something that should be simple, isn't.

 

[K PierreR]

It would be ideal if the same person do all the job, that is what I hope to find.

I have already bought a replacement bearing: CODEX EXTREME 628 2RS C3 P6Z3V3 / RLQ2 (what will be replaced on the picture)

Also have a second bearing on the same shaft on the other side (not seen in the picture) that will be replaced with SKF 16002-2Z. Hopefully the both replacements will let the center motor live a troublefree life.

Both bearings were recommended by a onlineshop (just selling bearings) after giving them all the details printed on the current ones.

I had a noise and just took mine apart. The shaft on the helical gear end is worn from spinning in the bearing race even though the bearing is not frozen up. The rotor must be replaced. might check yours for the same issue.

 

[K PierreR]

Wear shown here. Caused Error 30 code.

 

[K PierreR]

Another problem with pressing on a new bearing is the fact that the rotor has very strong magnets that will pick up any iron filings. Iron filings are a very common dirt around most presses in use. The magnets are strong enough that you might have great difficulty cleaning the rotor enough to reinstall it.

 

[K PierreR]

I just took a couple of flat screw drivers and levered them under the bearing as shown in your picture. The bearing popped right off with some effort.

 

[m4x]

@K PierreR

I never got any error code on mine bike display. Just the noise. My faulty bearing was in healthy condition from the outside. Could feel with the fingertip when turning it around that it was broken. Yours look really damaged.

 

[m4x]

Anyway, the new bearings are now finally replaced (workshop did it). I needed a very special tool to get the faulty bearing off: Kukko 43-001

Before I install everything back, I would like to grease the metallic rotor shaft/gear. The rotor shaft/gear will when installed back be working together with plastic gears inside the motor. I find some white grease on the plastic rotors (guess its white lithium grease?).

I have a tube of this bearing grease: Biltema hjullagerfett. Can it be mixed with the white grease? It has amber colour and says lithium based with EP additives in the description.