If you're serious about online racing simulators you'll own a Logitech G25 or G27* wheel. If you're really serious, you'll find the size of the steering wheel a little too small to feel realistic. This steering wheel boss adaptor allows you to replace the standard wheel with a Momo wheel on your G25.
Two downsides of this current design are:
1) You lose the two steering wheel buttons but I might consider improving the design to add these back in.
2) The paddles are now an inch further away and too short for my wheel. I don't use them so it doesn't bother me (yet).
*Apparently G27s are spaced differently so this won't fit. I'm sure it'd be easy to fix.
1) Print object
2) Remove standard wheel (6 hex bolts) and unclip two cables for buttons
3) Obtain 6 25mm x M5 (~= 1" x 3/16) countersunk bolts with nuts
4) Insert nuts into retaining holes underneath
5) Using original hex bolts, attach adaptor to wheel
6) Align Momo wheel and insert and tighten to taste
7) Enjoy the feel of a real wheel in your favourite games!