In view of the present fastening conditions of the suspension systems under passenger cars,two reliable and feasible fastening methods are given after comparison and analysis,i.

Through the problem of the crucial bolt connection failure in diesel engines, this paper analyzes the causes of failure in terms of design, manufacturing and fastening techniques, discusses several common tightening techniques of crucial bolts, points out the main cause of failure of the crucial bolt connection due to the improper bolt-on technique, and presents improved ways and methods.