Answer
In high-speed rotors (e.g., >10,000 RPM), any mass imbalance can cause significant vibration and bearing wear. Traditional stamped circlips are asymmetrical due to their assembly 'ears' or 'lugs,' which creates a significant mass imbalance. Spiral retaining rings are produced by coiling flat wire, resulting in a nearly perfectly symmetrical $360^\circ$ mass distribution. While they still have a small 'gap' or 'end offset,' the imbalance is orders of magnitude lower than a circlip. For ultra-high-speed applications, engineers specify a 'balanced' spiral ring, which features a series of small cut-outs on the opposite side of the wire ends to perfectly offset the mass. Failure to use a balanced ring in these systems results in excessive synchronous vibration ($1 \times$ RPM) and reduced life of the high-speed bearings.
