My rigged car import problem

I want the 3dmax car that i have created and rigged to be exported and do 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 …you will understand it better if you try it yourself if have both 3d max and unreal engine…Please i need your help