Start from the housing's designed geometry and assembly method
A split housing forms a bearing seat from assembled parts.
The cap joint, fasteners and locating features have their own manufacturer requirements. Bearing internal clearance depends on the bearing execution, fits and operating effects, so changing the housing joint is not a general-purpose clearance-setting method. Loosening a cap, adding an unapproved shim or changing tightening practice can alter support and geometry without resolving the original cause. The exact housing instructions must establish the intended assembly condition. A statement that “the bearing turns more easily with the cap loose” is an observation needing investigation, not approval to operate with a modified joint.