You can see how the different pinion shapes push the housing around with different amounts of force. The flat-bottom pinion is unable to provide any force to separate the housing (And engage the clutches). The 1.5-way only offers partial locking on deceleration.
Anyone have experience with the ATS diffs. Ive heard and seen nothing but good things, but Id like to know how they are from someone not selling them, and in general, how are 2 ways for day to day street driving.