First, I found an Neu 1717 on a forum, like new so I snapped it up.
Really happy with this motor, it's a beast compared to the 1515.
I then started thinking about how to gear it, because the maximum it can be geared with the Ansmann mount is about 21/46, which is pretty slow with a 1717 :P
I designed a custom mount on Google Sketchup.
After some rendering (only learnt how to do this yesterday :D)
Eventually, after some quotes I decided it was too expensive, because to take advantage of the massive slots I would need an enormous pinion gear, we're talking 40T!
I decided instead to figure out a way of making the centre diff smaller, instead of a 46T spur, maybe 28T or so.
I came up with this:
I think it should work quite well. It takes an 8mm bore mod1 pinion, needs to be 8mm as the bearings at 8mm, so it needs to fit over them.
I'll use a collar and set screw to stop it the bearings sliding off.