This will be a lengthy post, but hopefully it will be useful to anyone who has a Lionel 1588 shell laying around that they would like to repower with a Marx windup motor.
My goal in this repower was to install the Marx motor with minimal modifications to the Lionel shell. This included not making new holes in the shell for either the brake lever or key. The first step was to make motor mounts that would line up the motor's mainspring hub with the existing keyhole in the shell. I started with the rear motor mount. It is cut out of 22 gauge steel, and has a slight offset bent into it so the motor is at the proper height. A hole was drilled in the shell's original rear motor mount (the only shell modification needed for this project) and a single 8-32 machine screw holds the new motor mount in place. The machine screw does double duty, since it is also used to attach the rear coupler / drawbar. A custom coupler was made using a Marx tab & slot coupler with an extension soldered in place, and bent so it would line up properly.
Closeup of the rear motor mount:
The modified coupler. I run Marx cars behind my locomotive, but it wouldn't be hard to make a drawbar compatible with the original Lionel tender. The motor mount is held in place by the machine screw and a single nut, then the new coupler put in place on the screw, and two jam nuts tightened together to keep it in place while allowing it to move freely:
Next was the front mount. It was a bit more complicated. I made a custom mount that attached to an unusual Marx crossmember that I had in the parts bin... at least as far as windups go. It is similar to the one used on an electric 999; or one could be fabricated using a common Marx crossmember as a starting point (I did just that for my 999 windup project). Regardless, a small plate was cut from 22 gauge steel to connect to the Lionel's front mounting holes, and a round steel spacer was made to connect that plate to the Marx crossmember on the motor. A small hole was drilled in the crossmember, and it was bolted to the new mount with a 6-32 machine screw. The new front mount is attached to the shell with 4-40 machine screws - I may have had to tap the shell to fit (this was done a few years ago, so my memory is fuzzy on the details). The Marx crossmember had to be bent slightly in front to go over the Lionel siderod guides... although I could have removed them, I really didn't want to modify the shell unless absolutely necessary.
The Marx crossmember with the mounting hole drilled in the bottom. The front part has been slightly bent to clear the Lionel siderod guides:
The front mount. 4-40 machine screws hold the plate to the shell, and 6-32 machine screws are used to hold the round spacer to the plate, as well as to attach the Marx crossmember. You can see the original Lionel siderod guides, too:
The Marx crossmember & motor in place:
The motor mounted in the shell, as seen from the bottom:
Finally, the brake lever. The original Marx brake lever was bent over in a U shape. A new brake lever was cut out of 22 gauge sheet steel (see a pattern here?). It connects to the original Marx brake lever, and sticks up through the existing slot in the top of the Torpedo shell. A small cotter pin holds it in place.
A view of the brake lever attached to the Marx motor:
A closeup of the brake lever sticking up through the shell. The cotter pin keeps the lever up in position:
And that's it. The remotored Torpedo is ready for service: