FEDERAL FLEXIBLE COUPLING
https://federalmarinetransmissions.com/index.html
https://www.nautipedia.it/images/2/23/2021-federal-flexible-couplings-.pdf
Helpful Hints - for Installation of Federal Flexible Couplings
A Federal Flexible Coupling is a flexible propeller shaft coupling , consisting of an outer flange
containing compressed rubber bushings, and a ninne rhub attached by spider pins through the
bushings.
The Federal Flexible Coupling is not designed to correct engine misalignment , or bent shafts, or damaged engine bed components. Before doing installation, be certain engine alignment is proper.
Typically , the shape of the boat and the engine bed , are different on land compared to in the water . Proper engin e alignment needs to be done in the water , after boat an d engine bed re-shape , and using a fixed (rigid ) shaft flange .
Fiberglassboats can take up to a couple weeks to reshape , wood boats can take longer to swell . Alignment requires moving engine/transmission assembly around on motor mounts .
The industry standard for proper alignment of engine/transmission assembly , to a solid ( rigid - non flexible ) propeller shaft flange , is within .002 " or .003 " or less maximum . Be certain shaft flange , propeller shaft , motor mounts , and engine bed are in proper condition , so proper alignment can be achieved .
Propeller shafts vary in actual diameter by small amounts . The actual diameter of shaft will effect how a coupling (or flange ) assembles on to it - Some shaft flange shave been lightly sanded or fitted to particular shafts. Since shafts vary , there is no exact knowing how each flange will assemble , including a Federal Flexibl e Coupling . The object is a tight fit on shaft (not slip on and off) . B e certain to remove any burrand raised edge on shaft (especially from thrust are a at key way , and any set screw burr) . In reference to straigh t shafts, (not tapered) , if shaft fit is to o tight - a light polishing or sanding of inner hub bore can help . Shafts vary .
When assembling a coupling (flange ) onto shaft , some people are tempted to us e a wooden board and hammer, and drive flange on shaft. Whil e not the best method, please not e that the Federa l Flexible Couplings will resist progress, as the rubbers will do their job, absorbing much of the force you are trying to direct to inner hub . If required it would be more efficient to go direct to the inner hub . If clearance allows, you can place an object direct to inner hub from inside , and apply reasonable force . The more direct to inner hub area , the less the rubbers will absorb efforts to get hub on the shaft. Be certain not o harm components or shaft bore -
Like many couplings / flanges , the Federal Flexible Coupling uses set screws to help keep shaft from sliding out . These are 7/16"-1 4 square head and hardened , cup point set screw s with a hole in for safety wire. Like all flanges using set screws, be certain shaft is properly drilled the whole drill point, using proper size dril bit , so cup point of set screw fits down into th drilled "V " in shaft- If drilling the coupling in place , be certain not to ruin threads. Then properly safety wire the set screws. Some flanges have set screw sholes in different places. Examine the installation and redrill if required . Proper installation is important .
If you are not experience with doing proper engine alignment , or flange removal or installation , perhaps an experienced marine mechanic would be a solution.