That's a neat design. Should be easy to build too.
Somewhere in my head was brewing something similar and time learns again that someone already did it....
The rubber only has to take pull and push forces, no bending, undestructable!!!! Only disadvantige, the aluminium coupler would be bigger in diameter than original don't know if there is enough room...
Ok, who has all three donuts laying around, to make up a drawing for the aluminium rings.
http://www.maedler.de/katalog_de/katalo ... b16c03.htm
It can take a misalignment of 15 deg! For a a inside of 13mm the outside would be 30 mm, so the coupler would become ~25 mm lager in daimeter. I have only one laying around of a 4cil (don't know which one it is) but the outside dia =114mm so alu coupling would become ~135 mm .....
Max static torque for 3 of them (3x1760Nx46mm =)230 Nm is a bit low