Torsional Vibration Analysis

General Motors lab test sheets on Corvair Harmonic Balancer development.

Red lines at 1500 rpm and 4500 rpm are special problem areas for standard Corvair crankshaft.

The basic concept is that if there is more than 1/2 degree twist vibration
(torsional vibration), the crankshaft will eventually fail by cracking.
The goal of a good harmonic balancer design is to minimize those vibrations
to less than 1/2 degree at the problem r.p.m. areas.        

 "safe" limit of twist: (1/2 of a degree of the crankshaft) 'balancer tuning frequency in hertz (cycles per second)

 Ideal frequency of 222 hz. (208 to 238hz "safe" range)

Prime Mover  web link lost 11/01/2009