How to pull a bearing out of a blind hole?

With the crankcases split, I decided to replace all of the bearings but one in particular was a problem as it’s fitted into a blind hole, so I couldn’t drift it out from the opposite side like I did on the others.

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There may be an easier way but after a bit of head scratching I decided to try to make a threaded puller, that would go into the 15mm bore of the bearing and hook underneath the inner race. I started by turning a nut down to just under 15mm diameter on my friends lathe. I left a small step on one end at 16mm diameter for about 1 mm and then split the nut with a hacksaw, so that it would act like a split collet.

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This also gives clearance, so the 2 halves will go into the inner race, with the step engaging under the bearing at the bottom. The plan is to screw a bolt into the split nut and hope it keeps the lip under the inner race whilst the bearing is jacked out.

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I then made a steel spacer with a 36mm counterbore to clear the 35mm diameter of the bearing outer race.

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and the finished puller looks like this.

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I heated the casting with an electric heat gun to expand the aluminum and reduce the interference fit a little. Then I quickly screwed in the bolt, held the head and screwed the nut down. After a few turns it started to turn easier so something was happening, either the bearing was pulling out or the split nut was pulling through.

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and fortunately it was the bearing coming out – job done!

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One step forward and none backwards; now that must be a first!

 

 

 

 

 

 

 

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