L.A.B. said:
http://rocbo.lautre.net/technique/norton_workshop/012.html
"Spring -
No. of coils: 75 1/2 approx.
Free length: 18.687 in. (474.65 mm)
Rate: 36.5 Ib./in. Red paint marked "
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Own springs
Coils: 74.5
Free length: As above.
Outer diameter: 0.975" (approx.)
Inner diameter: 0.625" (approx.)
Gauge: 0.175"