unity 4.6 hinge joint broken in asset bundles

Hey guys

Since I upgraded to 4.6 all the hinge joints in my game is broken. The objects attached to the hinge joints are lying on the ground, like they would when the joint break force was applied. Strangely this only happens when I load the level from an asset bundle. If I play the level compiled from the build settings then the hinge joints act as normal, but when I rebuild the assetbundle and run the scene through the bundle the hinge joints break. As far as I can tell only hinge joints are affected. All the other physics is still as it used to be.

Any and all help will be hugely appreciated!