Wear and fretting fatigue are important technological problems in automotive, railway and aerospace fields. The purpose of this study is to find a method of reducing the wear of cast-iron (FCD)/aluminum components, which are often applied to automotives, and thus extend their lifetime. First, a stainless-steel (SUS) shim was designed, which can be inserted between an FCD plate and an aluminum plate. Second, diamond-like carbon (DLC) coatings were applied to the shim inserts to prevent the FCD and aluminum plates from wear. Then, the tribological and fatigue characteristics of the shim were evaluated by a ball-on-disk (BoD) test and a bending fatigue test of up to 1×10⁶ cycles. Each substrate was coated with DLC by Plasma-Based Ion Implantation and Deposition (PBII&D). A unique feature of our shim is that a segment-structured DLC film (S-DLC) is employed as well as a continuous DLC (C-DLC) film. The effect of the DLC coating on reducing the damage to the Al plate was apparent, because the surface roughness of the Al plate abraded with the DLC-coated shim was significantly smaller than that abraded directly with the FCD plate. Moreover, the average damage fraction to the C-DLC coating is approximately 20-fold larger than that to the S-DLC coating. The C-DLC film suffers severe damage near the bolt hole, whereas the S-DLC film suffered almost no damage even after 1×10⁶ bending cycles. In conclusion, an S-DLC-coated SUS shim has a marked effect on reducing the wear of Al/FCD components and improving their lifetime.