Quote Originally Posted by C9x
You probably wouldn't run into rpm related harmonics problems with your installation, but you can when running single springs at elevated rpm levels.

Little brother runs a 500 cid DRCE engine in his 8.13 second Henry J drag racer.
Rpms are 6800 at launch and 9200 rpm when shifted. (4-speed Lenco.)

He ran single springs for a while and every run he broke one.

The breakage quit after he went to dual springs.
The inner spring - whether round wire or flat spring stock - act as vibration dampers and keep the main - outer - spring from doing weird things harmonics-wise and self destructing.
OH MY !!! SINGLE SPRINGS TRYING TO RUN 9,200 RPM'S ??? WHAT ??? CAN YOU SAY COIL BIND !!!