Thanks for the answer
Today I was at the rc shop in my town and the guy at the shop said, that graupner speed motors (and a lot others) are made for planes, so have conical shaft, "circle" shaped.
As my original motor has "half circle" (or half moon, I don't know the exact term) shaped shaft, I have to find a replacement with the same type of shaft, if I want to mount the original pinion gear.
So I'd like to know if venom motor has "half moon" shaped motor shaft...
What about brushless ? Is there any cheap possibility for motor & controller ? What type of inrunner motor do I have to look for (how many rpm/V) ?
Thanks
Andrej