How do you confirm the integrity of the rear trailing arm bushings and subframe bushings on an E30? My 1991 318i has a brief speed-related shudder (vibration) when accelerating through about 5 mph. Engine, transmission and differential mounts, central drive shaft bearing have all been checked. Drivetrain is tight. The shudder is not clutch related and not rpm related. Through process of elimination I wonder if its the rear bushings.