My imported car3d max to unreal engine

I want the 3dmax car that i have created and rigged to be exported and do the same in unreal engine which i thought it would be the same in unreal engine. But the problem is that when i export my skeletal mesh and my physics assets from the same car in unreal engine, the bone(dummies) that i have used just breaks off…Google Drive: Sign-in will understand it better if you try it yourself if have both 3d max and unreal engine…Please i need your help guys…