Amazing! I have always been taught, and taught to others, that springs are among the most reliable of engineered structures.

At a glance, that illustrated spring failed for contact between the coil and the seat-coil.

This may be informative: Engineering Failure Analysis 15 (2008) 1155–1174
Design and Failure Modes of Automotive Suspension Springs

http://www.scribd.com/doc/27577332/D...ension-Springs

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