limbs shaking in game but not in preview

Hi everyone!

I m stuck here and decide to ask you some advices... let me explain.

I had a bunch of anims to do for an Unity's project, my first one, and everything went quite good for the most of them, except for animations using a Y translation. Every climb, jump or fall I'm making, are shaking at the very moment of the weight switch from the feet to the hand, to get up, and when its getting back to it.
This shake is visible only in-game, when I check those anims in the preview window, everything is fine and I m not talking about make them blend together, this is happening during the animation alone, I m using an avatar created from the model, no anim compression, no bake into pose checked and the Root transform position (Y) is in feet.
I m importing fbxs, baked frame by frame, from 3dsmax10 to unity 4.3.4f1.

is anyone with a solution here?
thanks!!

Alex

 

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