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.
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.
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.
I then made a steel spacer with a 36mm counterbore to clear the 35mm diameter of the bearing outer race.
and the finished puller looks like this.
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.
and fortunately it was the bearing coming out – job done!
One step forward and none backwards; now that must be a first!