Author Topic: BTH Pancake dynamo overhaul  (Read 879 times)

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Offline douglas1947

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BTH Pancake dynamo overhaul
« on: 11 Jan 2018 at 05:57 »
Hi,
I want to overhaul an BTH Pancake dynamo.
has anyone an idea, where I can get the 2 bearings?

Michael

Offline Doug

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Re: BTH Pancake dynamo overhaul
« Reply #1 on: 11 Jan 2018 at 18:02 »
Michael,

They are known as magneto bearings and are still available via bearing stockists and online. An online source that you can use to check sizes and part numbers:

https://simplybearings.co.uk/shop/Bearings-Magneto-Bearings/c3_4471/index.html

-Doug


Offline douglas1947

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Re: BTH Pancake dynamo overhaul
« Reply #2 on: 12 Jan 2018 at 06:39 »
Hi Doug,
thanks for the reply.
I have to find out, getting the old outside bearing rings out the housing (driving side) and armature (collector side).
Both are a bit rosty and warming up did not help.
May be I have to make a tool?

Michael

Offline Doug

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Re: BTH Pancake dynamo overhaul
« Reply #3 on: 12 Jan 2018 at 14:46 »
Michael,

The balls and cage will pop off the inner bearing race, as you may have already discovered.

Extracting the inner race is best done with a tool that works like a collet. It grabs the bearing race by the groove. (See picture) Something simple, like a worm drive hose clamp around the outside, prevents it from popping out of the groove.

Extracting the outer race is more difficult. It is hard to see if there is a gap between the bearing race and the armature, but it may depend on being able to get a tool in there to lever it out.

-Doug


Offline eddie

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Re: BTH Pancake dynamo overhaul
« Reply #4 on: 12 Jan 2018 at 17:29 »
Michael,
             If the outer track proves stubborn, try turning up a punch that is a good fit inside the smallest diameter of the outer track, then fill the bearing track and housing with thick grease, locate the punch in the centre of the track and drive it in. The grease will be displaced behind the track and will force it out. You may have to have several attempts to completely remove the track.

  Good luck,
                  Regards,
                                Eddie.

Offline ManfrerdSt

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Re: BTH Pancake dynamo overhaul
« Reply #5 on: 15 Jan 2018 at 17:45 »
this is what my tool looks like.
It works well at BTH and Lucas
Regards
     Manfred

Offline douglas1947

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Re: BTH Pancake dynamo overhaul
« Reply #6 on: 26 Jan 2018 at 12:20 »
Hi,

thanks for all ideas and help.
The bearings are all out and but I have to do some modifications to fit new bearings.

Michael