We've recently upgraded our project to Unity 5. However, we're running into problems with the new Joints that came with the new version of PhysX. In Unity 4.6, we could attach a chain of rigidbodies to a ragdoll, and then drag the ragdoll over obstacles like rocks, stairs, etc. Even if we managed to get the ragdoll stuck in an area where it couldn't fit through the simulation would remain very stable even as we continued to pull on the chain. If, somehow, the ragdoll or the chain started to jitter around because you were pulling on the chain too hard, as soon as you stopped pulling on the chain it would become stable again. However, in 5, the exact same setup causes the joints to freak out very easily. Once the freakout starts, it never subsides, even after the force that introduced it is taken away. In other words, once it starts, it never stops. To combat this, we've increased the inertia tensors to something much higher than what it gets set to by default. This fixes it in most cases, but then objects don't behave realistically at all - the rope was stiff and seemed as though it could not be rotated - the ragdoll looked as though it were being held up by some ghost force. But even with these measures in place, it was still very easy to drag the ragdoll through something that'd cause it to explode forever. These are all situations that Unity 4.6's PhysX version could handle very easily, and with almost no instability. The next thing we thought of doing was decreasing the maximum angular velocity of all of the rigidbodies involved... but... why exactly are we needing to butcher the physics so much in the first place, just to get it working? What exactly changed, and how do we fix this?