Last updated on 10/26/2023
GLM Marine 21520 Bearing perload and gear set up installation
The latest Alpha One or gen. 2 outdrive units, beginning with serial number 0D492656 and above, no longer use the cone spacer between the bearings in the U-joint assembly to set the bearing pre-load and is covered in the following instructions. Also, the 0.D. of the new drive gear hub was increased by .0014 inch, which means that the bearing cones (old or new) now have a slight “interference fit” with the gear. It is important to note that these gear sets and bearing sets will back-fit to drive units that fall below the above listed serial number and that the new bearing pre-load procedure must also be used for those units. In those cases where the 21520 Bearing Set is used in conjunction with the original (slip fit) gear, the cone spacer must be used, and the old bearing pre-load procedure must be followed.