Official Answer
Answer
The clearance between the ring thickness $t$ and the groove width $G_w$ should be kept to a minimum to prevent axial 'shuttling' and to ensure the ring remains perpendicular to the load. A typical specification is $G_{width} = t_{max} + 0.05$ mm. Excessive clearance allows the ring to tilt under load, which creates a 'wedging' effect that can lead to groove failure or dislodgement. However, some clearance is necessary to account for the 'dish' tolerance of the ring and to allow for thermal expansion. In precision applications, 'selective fitting' or 'shimming' may be used, though this is rare for retaining rings; instead, a wave spring is often added to take up all axial play.
