Hard disk drive non-uniform disk shroud clearance

A hard disk drive enclosure base includes a non-uniform disk shroud surface extending from a top to a floor, the shroud surface including a first portion having a first radius and clearance along the circumference of the shroud surface and a second portion having a lesser second radius and clearance. The second portion of the shroud surface may be positioned at multiple locations where the drive form factor is especially constraining and in view of the need for a sufficient seal land surface for applying a gasket seal around the perimeter of the inner cavity of the base part. Widening the disk shroud clearance where possible can reduce the shear stress exerted at the disk edges thereby reducing the windage drag and associated disk spindle motor power consumption, especially in the context of helium-filled drives in which disk flutter is less of an issue.