Bearing stuck to axle

Anybody got any ideas for getting a bearing off an axle in one piece or getting the motor back together with that stuck there? Right now my best idea is to use a gear puller to push it all back together since that's how it got yanked out in the first place. Bearing still seems to work, not sure why it's stuck. Thinking there is a high likelihood of failure with any route I take, so pretty resigned to not having an ebike on vacation with me. So I'll probably need to know what size bearing a 9c take to buy a new one if anyone happens to know that and any installation tips.

did you damage it? was there a reason to take it off? if not and it is smooth you can push it back against the stator. slip some tubing over the shaft against the inner race and it should go back with a light hammer or press if you wanna.

Heat the bearing with a hot hair blower (of a hair dryer), it will expand slightly and you'll be able to slide it on or off the shaft.

Avner.

There is a limit to how much force the bearings can transmit sideways from one race to the other before the balls get dented. I have a local supplier that sells them by the 10's for cheap enough (<$20) that it makes replacement a form of cheap insurance.

Another implementation of the temperature differential method is to use dry ice on the axle with foil to insulate it followed by quick pinpoint heat on the inner bearing race. Some Kroil penetrating oil seems to help, too.

This All Balls installation guide has a great graphic that illustrates what's going on with the bearing. It can be a tricky finesse to get the bearing installed with no side-load.
https://www.allballsracing.com/media/installation/Wheel_Bearing_Install.pdf

For installation, chill the axle/heat the bearing and then seat both the inner races firmly against the axle stops. Then chill the axle/bearings and heat the side covers in the oven so they slip easily onto the bearings without introducing side-load in the bearing.

I agree with the heat and cold suggestions. It really helps a lot when dealing with metals that are interference fit and especially if different material. If you can make a sleeve (pipe) that will fit over the axle but put pressure on the inner race. With some heat and tapping on this sleeve, it should wiggle out.

If that doesn't work, there are also things for removing stuck bolts like CRC Freeze-off

if the shaft is damaged then this heat/cool stuff means nothing. that is not how bearings are mounted on the shaft.

your axle may even be bent but if there is nothing wrong with the bearing you should leave it alone.

dnmun said:

… this heat/cool stuff … is not how bearings are mounted on the shaft.

your axle may even be bent but if there is nothing wrong with the bearing you should leave it alone.

Click to expand...

By definition, the process of taking the side cover off potentially damages the bearings depending on how much force is used.

Its true that you can press the bearing into the side cover first via pressure on the outer race, then press together the cover/bearing assembly onto the shaft via pressure on the inner race.

The temperature differential method in my earlier post may in fact cause the cover to expand to a size larger (at the outer edge) than the hub it goes into. That qualified, temperature differential is a legitimate method/aid for interference fit assembly.

gogo said:

dnmun said:

… this heat/cool stuff … is not how bearings are mounted on the shaft.

your axle may even be bent but if there is nothing wrong with the bearing you should leave it alone.

Click to expand...

By definition, the process of taking the side cover off potentially damages the bearings depending on how much force is used.

Its true that you can press the bearing into the side cover first via pressure on the outer race, then press together the cover/bearing assembly onto the shaft via pressure on the inner race.

The temperature differential method in my earlier post may in fact cause the cover to expand to a size larger (at the outer edge) than the hub it goes into. That qualified, temperature differential is a legitimate method/aid for interference fit assembly.

Click to expand...

Agreed! I should be more clear, I only mention using the inner race for REMOVAL of a bearing. I don't ever expect to reinstall a bearing after pulling it in that manner. Bearings, if pulled on the inner race, you might get damaged on the balls or carrier or races. For things like skateboards, where the bearing fit is not as tight, damage is less likely and you can reuse after cleaning and relubing. I have not reused bearings in hub motors since I usually upgrade after pulling them.

For installing, definitely tap only on the outer race. (if installing into a carrier, tap on inner race when putting onto a shaft)

Became clear I wasn't going to have enough time to mess around with removing and replacing the bearings before the trip, so I went ahead and just used the gear pulled on the other side to smash everything back together. Bearing probably isn't in the best shape any more, but seems to be working alright. Not planning to do too much biking on the trip, so hopefully it'll be good enough.

If you can feel any "texture" in the bearing when you spin it, it's toast. Done.

Replace the bearing every time you pull it; it's cheap. Use grease on the inside and outside every time you reinstall.