I have been using a 3 USD MPU6050 for some time and found out that the gyro signal is reduced when side way accelleration is encountered. In my application the gyro signal disappears at 9g accelleration.
To verify this I have made a test stand on a record player, the rotation of a record is approx 200 degrees per second. Once rotating I lifted the side of the record player to create a side force on the sensor. In the data I can clearly see the gyro signal being influenced bij this force. At 65 degrees elevation a loss of 15 degrees per second is measured between the top (minus gravity) and bottom (plus gravity)
I repeated this test with a more expensive board from flyduino. With this sensor the rotation is stable, no matter the position of the turn table.
Both sensors have the name of the manufacturer on the encapsulation.
Sparkfun sells this sensor at USD 38 so I do expect some differences.
I tried to find more posts about this effect but was unable to find one. Anyone having the same problems?