AKG Motorsport - BMW Rear Trailing Arm Bushings, Poly 75D – E36, E46, Z4These BMW E36, E46, Z4 Polyurethane (75D) Rear Trailing Arm Bushings (RTAB) virtually eliminate movement of the rear trailing arms to prevent geometry changes keeping alignment and handling consistent. In addition, our unique bushing design incorporates grease grooves for easy lubrication. The factory rubber rear trailing arm bushings are soft and wear out quickly, creating fluctuations in suspension geometry that adversely affects everything from