SA dyno hub bearing servicing help



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Robert Box

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Can someone please direct me to some instructions for servicing a front Sturmey Archer dyno hub? I
want to clean and grease the hub but do not want to damage the magnet by improperly disassembling
it. Also , a picture of the "keeper" and its dimensions would be helpful also.

Thanks Robert
 
A

A Muzi

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"Robert Box" <[email protected]> wrote in message
news:[email protected]...
> Can someone please direct me to some instructions for servicing a front Sturmey Archer dyno hub? I
> want to clean and grease the hub but do not want to damage the magnet by improperly disassembling
> it. Also , a picture of the "keeper" and its dimensions would be helpful also.

Right you are to hesitate before opening that hub.

A keeper is just a hunk of steel about the size of your armature that can be slid in right behind
the armature so there's always a hunk of metal inside the magnet. The official S.A. keeper and Jim
Adney's model are nice lathe-turned solid steel plugs. My stack of nine flat 16t cogs wired together
works fine ( I just happen to have a lot of cogs here).

Once opened, a toothbrush and your favorite cleaning solvent are fine for getting all the crud out.
I locktite the armature retaining nuts because overtightening them can dimple the hub shell. I don't
know the proper wrench size for those, but a Simplex 5mm socket is a good fit. When you reinstall
the hub dust caps, use a flat piece of steel to press or tap them flush with the hubshell. Those can
dent when smacked with a hammer.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
 
S

Sheldon Brown

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Robert Box wrote:

> Can someone please direct me to some instructions for servicing a front Sturmey Archer dyno hub?
> I want to clean and grease the hub but do not want to damage the magnet by improperly
> disassembling it.

See: http://sheldonbrown.com/dynohubs.html

> Also , a picture of the "keeper" and its dimensions would be helpful also.

The keeper is an iron hockey puck the same size as the armature.

This is a useless tool these days. The only reason you might need a keeper would be if you had
a good magnet with a bad armature, and had a good replacement armature to install in place of
the bad one.

Otherwise, there is no need to separate the armature from the magnet, thus no need for the keeper!

Sheldon "Where Would You Find An Armature?" Brown +--------------------------------------------+
| Most people would sooner die than think; | in fact, they do so." - Bertrand Russell |
+--------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
 
M

M-Gineering Imp

Guest
Sheldon Brown wrote:

The only reason you might need a
> keeper would be if you had a good magnet with a bad armature, and had a good replacement armature
> to install in place of the bad one.
>
> Otherwise, there is no need to separate the armature from the magnet, thus no need for the keeper!
>
> Sheldon "Where Would You Find An Armature?" Brown

here's one: http://WWW.OLDBIKETRADER.CO.UK/index.php

--
Marten
 
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