I am curious what this marking on my 1973 front disc means ???

It is on the side where the disc meets the hub.
Dennis

DennisMo said:

It is on the side where the disc meets the hub.
Dennis

View attachment 131039

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Dennis, I really don't know, but it appears to be some type of ancient Egyptian hieroglyphics. Perhaps it was made in Egypt while King Tut was doing his thing 1332 AD. You never know where Norton sourced their parts.

If you spin it anti clockwise @33.3 rpm, it will spell "I love Yoko"

Some smarty-pants bet his mate on the assembly line that it would get past QC.

It did.

NORTSTER1974 said:

Perhaps it was made in Egypt while King Tut was doing his thing 1332 AD.

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The technology of producing cast iron progressed from China to Europe in the 12th-13th century and was refined in Europe by the invention of the blast furnace, making it possible to produce homogeneous iron on an industrial scale. As often is the case, it was military demands which led to advances in technology, and in this case, the need for cannons and shots. As for the lathe, designs with flywheels and cranks, providing continuous rotation, were sketched by Leonardo da Vinci in the 15th century, including metalworking concepts. So realistically, a cast iron brake disc could have been made in Birmingham during the industrial revolution (1750 onwards), not in Egypt, even though the lathe was invented there.

- Knut ;-)