Introduction Some vehicle drive train parts have remained unchanged for many years. Most drive train systems, how- ever, have undergone changes, and many new drive train parts have been introduced. Many manual transmissions now contain as many as six forward gears, compared to the three-speed units of years ago. Components that were rare in the past, such as transfer cases, limited-slip differentials, and two-piece drive shafts, are increasingly found on light trucks and SUVs. Transaxles and CV axles, once novelties, are now used on most automobiles. Some vehicles are equipped with completely new drive train systems, such as electronically controlled transfer cases and hydraulically locking differentials. In the past, the drive train technician could learn by doing, that is, learn about parts and systems as he or she performed repairs. Today, this is no longer possible. Experimentation cannot be tolerated in today’s competitive repair market. Both labor and parts are too expensive to be wasted on trial-and-error methods. Since many drive train parts are controlled by or send a signal to the on-board computer, the technician must have an understanding of basic electricity and electronics and must know how to use a scan tool to diagnose these drive train parts. Today’s tech- nician must also be aware of the special service tools required by many components and the procedures used to repair the more easily damaged drive train parts that are made of aluminum and magnesium. Manual Drive Trains and Axles provides theory and service information for all modern drive train components. This includes information on the latest versions of clutches, manual transmissions and transaxles, solid and independent rear axle assemblies, drive shafts and drive axles, U-joints, CV joints, and center supports. Basic drive train components such as gears, bearings, and seals are identified and explained, along with the principles of hydraulic systems. The text also includes basic electricity and electronic principles, detailed explanations of the operation of electronically controlled components, and overall electronic control systems. The textbook is arranged so that operating principles, system designs, and component parts are fully explained before diagnosis and repair procedures are discussed. Each chapter begins with a list of objectives that identify the focus of the chapter. The beginning of each chapter also contains a list of important technical terms. Look for these terms as you read through each chapter. They are presented in bold italic type when first used in the text and are defined when introduced. Figure references are presented in bold type for ease of identification. Notes provide supplemental information on the material presented in the text. Cautions are presented when the risk of property damage is possible. Warnings are presented when personal injury is possible, either during service or when the vehicle is operated after repairs. Each chapter closes with a Summary, Review Questions, and ASE-Type Questions. In a few years, it will become difficult for the automotive technician to get a job if he or she is not ASE certified. The National Institute for Automotive Service Excellence, or ASE, was established more than 45 years ago to increase technician standards by, among other things, giving a series of standard- ized tests in various automotive areas. Manual Drive Trains and Axles is a valuable aid to those preparing for the ASE cer- tification test A3, Manual Drive Trains and Axles. The content is correlated to the ASE/NATEF task list. ASE-type questions at the end of each chapter help prepare you for the kinds of questions asked on the ASE tests. In addition, Chapter 21 pro- vides information on preparing for and taking the ASE tests. A workbook correlated to Manual Drive Trains and Axles is also available. The workbook contains additional test questions, including more ASE-type questions. The chapters in the workbook are correlated to those in the text- book. The workbook also has drive train related jobs that develop your ability to perform hands-on service. By choosing Manual Drive Trains and Axles, you have made a good start in preparing for a future in the field of automotive service and repair. Chris Johanson 3