Figure 1. Center Prop Shaft
Check that coupling centerlines align by butting propeller shaft coupling against transmission coupling. (Figure 2) Shoulder on propeller shaft coupling face should engage recess on transmission coupling face with no resistance.
Figure 2. Coupling Flange Alignment
Note: Some propeller shaft couplings may not have a shoulder on mating face. On these installations, use a straight edge to check centerline alignment.
Check for any angular misalignment. Hold coupling faces tightly together and check for a gap between coupling faces with a .003" (0.07 mm) feeler gauge at 90-degree intervals (Figure 3).
Figure 3. Angular Alignment