Indeed, the Razor 9DOF imu is really sensitive to vibrations. Motor vibrations cause that much noise on the sensors that this board really can't be used in a multicopter. But you can fix this with some tips & tricks.
I really have tested everything to reduce vibrations. Nylon spacers/srews, foam, rubbers, rubber band,... just everything you can imagine. The only thing that really helps to reduce vibration noise is to make a motor mount that is completely saperated from the frame by some rubbers. I will give more details on this in my next blog.
With homemade motormount I was able to
- reduce GYRO noise to 1%
- reduce ACC noise with 90%
I also noticed that increasing the ACC update rate increases the noise on the raw data. I currently update my ACC at 12hz to get a good result.
But by using the GYRO (100hz) data and ACC (12hz) data in one formula I still have an output rate at 100hz!