Summary

Another alternative to mount a 3.17mm (1/8") shaft motor in the Tarmo4 car.

After printing the input gear, use a soldering iron to push a 48p, 12tooth pinion gear into place. If you aren't sure how to do it, look up one of the 3d printing "how to use threaded inserts" (this one on CNC Kitchen/YouTube has a nice close up at start: https://www.youtube.com/watch?v=iR6OBlSzp7I&vl=en)

Make sure the grub screw is still accessible after inserting the gear.

My motor is also a front mount, six hole pattern, so I've included the mount for that as well. You'll need to drill two new holes into the body, though you might get away with using just the back two (which mount in the original holes).

STL and STEP files included.

Enjoy!