Quick question, does the orientation of the gear tooth sensors make a huge difference in results? I’ve seen that most gear tooths sensors will be mounted vertically (in the frame of reference to the ground), but since it’s just a magnet being triggered by the gears, could it potentially be mounted horizontally? As long as it’s ~1mm away from the gear teeth should it not still work? If anyone knows could they post quickly please, I need to know in about an hour or less. 
We have gear tooth sensors mounted in a variety of orientations and they all work well. The important thing to remember is that you must have the active face of the sensor lined up with the gear as shown on page 5 of the datasheet: http://www.allegromicro.com/datafile/0642.pdf