SA GH6 dynohub axle replacement

[gregory]

gentlemen,

i need to replace the axle on a second-hand GH6 front wheel dynohub.
production date is 1966.
Wrong nuts were used on this hub by a previous owner - unfortunately i
have no way of measuring the threading, as it is almost completely
gone.
could someone tell me the correct threading?
i do have a box full of various SA hubs, is there any chance i could
use an axle out of another (non-dynohub) SA hub? (perhaps the front
internal brake hubs used the same axles?) i checked some old SA manuals
but the ID-codes for the axles do not match - but then again the axles
are not the same length, etc.
any pointing me in any direction would be grately appreciated :)

thank you,
gregory

[jobst.brandt@stanfordalumni.org]

Gregory Raye writes:

> I need to replace the axle on a second-hand GH6 front wheel Dynohub.
> production date is 1966. Wrong nuts were used on this hub by a
> previous owner - unfortunately I have no way of measuring the
> threading, as it is almost completely gone.

> Could someone tell me the correct threading?

3/8-24TPI

> I do have a box full of various SA hubs, is there any chance i could
> use an axle out of another (non-Dynohub) SA hub? (perhaps the front
> internal brake hubs used the same axles?) I checked some old SA
> manuals but the ID-codes for the axles do not match - but then again
> the axles are not the same length, etc.

One important feature is to heed the cryptic instruction on the hub that
says:

"Do not remove without keeper"

No one that I know has a keeper but just the same

DO NOT TAKE TH STATOR OUT OF THE HUB

or better said do not take the stator out of the magnet or it will be
permanently demagnetized... instantaneously. This is an ALNICO magnet
that cannot retain its magnetism outside of a closed magnetic circuit.
Once separated, the Dynohub will produce about half its designed
voltage... that isn't much anyway.

I built a magnetizer and discovered that this archaic design isn't worth
rebuilding. There are good ones on the market today.

Jobst Brandt

[gregory]

thank you Jobst for the information.
i am aware that there are new dynohubs today, but would still like to
fix the SA hub, as (except the axle) it is working well.
i had a look at the hub and i think it should be possible to get the
axle out of the hub without removing the magnet - is this correct?
greetings,
gregory

[m-gineering]

gregory wrote:
>
> gentlemen,
>
> i need to replace the axle on a second-hand GH6 front wheel dynohub.
> production date is 1966.
> Wrong nuts were used on this hub by a previous owner - unfortunately i
> have no way of measuring the threading, as it is almost completely
> gone.
> could someone tell me the correct threading?
> i do have a box full of various SA hubs, is there any chance i could
> use an axle out of another (non-dynohub) SA hub? (perhaps the front
> internal brake hubs used the same axles?) i checked some old SA manuals
> but the ID-codes for the axles do not match - but then again the axles
> are not the same length, etc.
> any pointing me in any direction would be grately appreciated :)
>


www.hadland.net for all SA information,as in:

http://www.users.globalnet.co.uk/~hadland/samaintind.htm
http://www.users.globalnet.co.uk/%7ehadland/gill.html

---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

[jobst.brandt@stanfordalumni.org]

Gregory rayee? writes:

> I am aware that there are new dynohubs today, but would still like
> to fix the SA hub, as (except the axle) it is working well. I had a
> look at the hub and I think it should be possible to get the axle
> out of the hub without removing the magnet - is this correct?

In fact you can even take the magnet out of the hub if you make sure
it remains ON the stator. The magnet has a paper backing so that it
won't rattle. Just make sure the stator and magnet are not separated.

Unfortunately there are no call-outs pointing at the various
components on the SA drawing:

http://www.users.globalnet.co.uk/~hadland/sa/sagh6.pdf

but the ring around the magnet in the drawing is paper. Of course, no
"keeper" is shown although, as always, it is mentioned. I've never
seen one other than the solid iron block I made to measure the field
strength before and after magnetizing. Other than that, the magnet
had to be carefully pushed from the magnetizer core onto the stator
with no slip-ups.

Jobst Brandt