Usage:
7271 Marine Transmissions
Description of Change: The output shaft group used in 7271 Marine Transmissions has been improved. Formerly the output flange assembly was held in position on the end of the output shaft by a retainer plate, and four bolts and lockwashers. The improved output shaft group uses eight longer bolts to fasten the retainer plate to the output shaft. The longer bolts provide more bolt stretch and decrease the chance of bolt breakage.
Illustration 1. Location of the improved components in the 3N6164 Output Shaft Group.
Adaptable To: The new and former components of the 3N6164 Output Shaft Group are listed in the chart and shown in Illustration 1. The new components, when used together are adaptable to all earlier 7271 Marine transmissions.
Earlier 3N9234 Shafts can be modified to use four of the longer 7B5163 Bolts if breakage of the former T856 Bolts has been a problem. Use the procedure that follows to modify the 3N9234 Shaft.
Modification Procedure
1. Use two T856 Bolts to install a 7T821 Plate on the end of the 3N9234 Shaft.
2. Use the 7T821 Plate as a template to drill, counterbore, and tap the other two holes deeper in the end of the shaft as shown in Illustration 2.
3. Install two of the new 7B5163 Bolts in the deeper holes machined in Step 2. Remove the two T856 Bolts.
Illustration 2. Dimensions for modifying 3N9234 Shafts to use longer 7B5163 Bolts.
4. Drill, counterbore and tap the two holes, where the T856 Bolts were removed, deeper as shown in Illustration 2.
5. Install two 7B5163 Bolts in the deeper holes.