Best way to remove crank bearings

I have the manual and this is one thing it does not give clear direction on. After the cases are split, what is the best way to get them out?

Take a nut and lay the case half at inner side and heat the case around the bearing. Then you can slam the bearings out

put the inside of the case half face down on the bench, use a socket the same size as a bearing race and tap the bearing out. It takes a bit of force, but not to to much.

 

To put new bearings in. Take new bearings and put them in freezer overnight or at least a few hours, heat the cases gently with a propane torch around where the bearings go. The new ones will drop right in with zero force if done properly

I prefer a press, the proper method IMO for crank or most bearings is pressing them in or out. I tried a hammer method once, cost me a crankcase half.:( 

I prefer a press, the proper method IMO for crank or most bearings is pressing them in or out. I tried a hammer method once, cost me a crankcase half. :(

 

 

Press is preferable. 

 

 

I have done at least 20 engines without press. using just a propane torch, hammers, sockets.

Edited by adam8781

What I do is take a torch and heat up around the bearing on a case and get a socket to pound it out. Or you can put it in the oven around like 200 degrees for 20 min and that should work too

What I do is take a torch and heat up around the bearing on a case and get a socket to pound it out. Or you can put it in the oven around like 200 degrees for 20 min and that should work too

 

Oven wont work to pull bearings, When you heat the cases the metal expands, if you heat the bearings and cases at the same time to the same temp they both expand, So they are just as hard to get out of the case if it was cold, but now everything is hot to the touch. Only way heat works is if you heat the case (gently) around the bearing with a torch and push the still cold bearing out.

Got em out.. Heated the case halves up with propane torch.... Leary as heck about heating them up too hot, so I had a laser thermometer. It seems 170 degrees was the magic number. I used a race/seal remover and after a couple careful yet sturdy whacks... They dropped out.

Wooo hooo!!!

I pulled the bad bearing apart as I wanted to try and determine the root cause of failure. The inside race of the bearing was badly pitted and looks like it had been for some time!

Dunno if it was corrosion or poor quality. It is a Koyo. The bike had sat for 10 years.

Between the bad seal and bad race I think that is what caused the bearing failure.

Yz autopsy complete.

If it is a blind bearing heat is about your only option as well. I agree with the other guys.

Oven wont work to pull bearings, When you heat the cases the metal expands, if you heat the bearings and cases at the same time to the same temp they both expand, So they are just as hard to get out of the case if it was cold, but now everything is hot to the touch. Only way heat works is if you heat the case (gently) around the bearing with a torch and push the still cold bearing out.

 

Wrong, the thin aluminum cases expand quicker than the steel bearings. Throw the cases in the oven for 15-20min and they will usually just fall out for you. Otherwise they will just need a gentle nudge with a socket and hammer.

With assembly if you freeze the bearings in the oven for 24hrs and heat the cases they will just fall in to place, generally no pressing/driving needed.

Pitting on inner race.

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Wrong, the thin aluminum cases expand quicker than the steel bearings. Throw the cases in the oven for 15-20min and they will usually just fall out for you. Otherwise they will just need a gentle nudge with a socket and hammer.

With assembly if you freeze the bearings in the oven for 24hrs and heat the cases they will just fall in to place, generally no pressing/driving needed.

correct aluminium expands at 6 times the rate of most ferris materials

I have the manual and this is one thing it does not give clear direction on. After the cases are split, what is the best way to get them out?

Put the case halfs in the freezer overnight. Heat the case around the crank bearing and slam the case off a sturdy wood bench top the bearings will eject easy, or you can use a hammer and socket. You should ONLY need light taps with a hammer. Might take a few tries if you don't heat the case enough. Done this "freeze n heat" method for the past 30 years. No need for expensive bearing pullers. Same method , reverse the procedure for installing the crank bearings. It's far easier for a novice mechanic to do damage with a press by not pressing the bearing in squarely.

Edited by Polar_Bus

I like to use a oven they just fall out

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