In order to install the modifications a horizontal cut is required just above the two 1/4 inch protrusions.The piece that is cut off which contains the upper bearing will be reinstalled on the frame extension pieces. Note the opening for the main drive gear has also been increased.
These pieces move the upper bearing 3/8 inch further away from the lower bearing. This allows clearance for the belt drive pulley and the elevator crank assembly. They are attached to the sides of the frame using screws and cupped washers. Please note I used salvaged printed circuit board for the modifications.
The tail boom mount was machined from nylon, it was designed to move the boom up 1/4 of an inch and out by 3/8 of an inch. The mount is bolted to the original using countersunk head screws. The original boom clamp was reused. To guide the belt into the boom 2 pulleys were machined each are mounted on two ball bearings and secured to the new boom mount with 2/56 socket head cap screws. Note that the frame spacer originally located above the motor drive gear was replaced with a machined spacer mounted between the extensions mounting locations.
The drive pulley inside diameter was machined to fit over the main gear hub. A bearing was also installed in the drive pulley to support the whole assembly. The main gear is clamped between the drive pulley and a tapped aluminium clamp ring using 2/56 socket head cap screws. Please note the pulley rim diameter was also reduced so that it would fit between the elevator crank assembly. Also the main gear has been flipped upside down , the one way bearing was removed and reinstalled to accommodate this action.
No modifications are required to the Elevator Crank, however longer bushings had to be made to centre the assembly between the extension pieces.
The stock aluminium shaft was replaced with a steel shaft. This shaft need to be 3/8 of an inch longer. This was accommodated by machining a insert that was pressed in and then machined to the outside diameter of the shaft. A longer collective pitch rod was also installed
The hexagonal tail shaft was used to broach a hexagonal hole in an aluminium bushing on which the Tail Shaft pulley was installed.
The completed installation, note the cupped washers, the spacer and the pulleys.