Tempering Springs

["Reid, Warren" <Warren.Reid@xxxxxxxxxxxxxxxxxxx>]

Just an interesting point to note on automotive suspension springs which
prompted me by Mark Battley's front spring lowering exercise. (Not that this
in any way answers your question, Mark) Most people do not realise that its
impossible to alter the stiffness of a suspension spring (or any other
spring for that matter) by tempering it.The stiffness of the spring
(assuming you do not change its length, diameter etc) is only governed by
the Elastic modulus (Young's Modulus) of the material making up that spring.
The elastic modulus of steel is based purely upon the crystallographic make
up. What you do change is the set point at which yielding or permanent
plastic deformation of that spring occurs. One of the major problems with
105 series cars is that they develop the  characteristic droppy tail
syndrome because of this. Generally the operating stress of the spring has
been to close to the onset of plastic deformation and over the years the
springs slowly take up a new set point because of this.

Warren Reid
Melbourne, Australia
68 1750 GTV
86 Spider Veloce
84 Alfetta GCL
58 and 61 Bugeyes

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