Magneto bearing puller

 With these old bikes every new job is a challenge. I suppose I could have sent the dynamo away to be refurbished like I do the magnetos but they're not that complicated so I do them myself. 

The E3 fitted to the Model A is a little bit different to the later E3Ls and E3HMs that I've worked on in that it uses magneto style bearings with separate races, cages and balls. Simple enough you might think - well yes, if it all goes to plan. 

What I discovered was that the reproduction armature that I bought for the E3 on the Model A, the first three-brush dynamo I have worked on, wasn't quite the same dimensionally as the old bent armature that came out and I found when I fitted the bearings for the first time that I had far more endfloat than I could cope with. To fix that you need to remove the bearing again, put a spacer in behind it to take up the end float, and fit the bearing back again - and you might end up doing this two or three times.

You need a special puller to remove the bearings and I found the details for one here:

https://www.kynoch-douglas-parts.com/html/articles/magneto%20bearing%20extractor.htm

The main tube part of the puller is made from a bit of old handlebar which I've turned internally to make the hemispherical form that will fit into the bearing race.

I turned up a plug to go in the end of that with an M8 female thread in the middle and welded it into the end of the tube. The six slots were cut with a hacksaw - you could make a much better job with a slitting saw but frankly I didn't want to work of setting it up.

There are a couple more details - the end of the threaded rod has a small disc welded to it to bear on the end of the armature shaft to reduce the likelihood of damage and the other end has a t-piece to allow you to turn it easily.

Here it is in action. Initially I used a regular worm drive jubilee clip to hold the six legs into the bearing, but they are just not strong enough and will pop out. The worm drive does not allow you to put sufficient force into the legs so I have used a much better quality hose clip - this trunnion type clip:

It works very well but you do need quite a lot of force to remove those bearings.