The primary goal of this book is to present suitable methodologies for dynamic analysis of multibody mechanical systems with imperfect or real joints, that is, considering clearances, including their tribological characteristics and surface compliance properties. Two and three-dimensional methodologies for imperfect kinematic joints with and without lubrication are presented. In the process, different contact-impact force models are revised in face of their suitability to represent collision between the bodies connected by imperfect joints. The incorporation of friction forces, based on the Coulomb friction law, is also discussed together with an effective computational strategy. Further, a general methodology, which accounts for squeeze-film and wedge-film actions, including the cavitation effect, for modeling dynamically loaded journal-bearings is also presented. This book is written for academics, students and practitioners in mechanical engineering, design, researchers in the field and teaching staff. This book is can also be used in the final year of the studies of MSc students or in the beginning of the studies of PhD students in mechanics and computation sciences.