New control arm front ball joint nuts will be required upon installation. To remove the trailing arm, block the rear wheels, apply the parking brake, and raise the front of the vehicle. Support it securely on jackstands and remove the appropriate front wheel. Remove the engine under-shield by removing the fasteners. If the model is equipped with suspension ride-height sensors, release the clamp and disconnect the sensor link bracket from the arm. Unscrew the trailing arm ball joint nut until the edge of the nut is flush with the end of the ball joint shank. Tap the end of the ball joint shank with a soft-faced hammer to release the arm from the hub carrier. Remove the nut and pull the inner mounting bolt from the trailing arm. Remove the lower arm assembly from underneath the vehicle. The ball joint may be a tight fit in the crossmember and may need to be tapped to release it. To remove the tension strut, remove the tension strut ball joint nut. If necessary, use a Torx bit to counter-hold the nut. Release the arm from the hub carrier by tapping the end of the ball joint shank with a soft-faced hammer. Remove the inner mounting bolt and remove the strut from the subframe. Thoroughly clean the arm or strut and the area around the mounts. Check for cracks, distortion, or any signs of wear or damage. Pay attention to the mount bushings and ball joint. To install the trailing arm, locate the inner end of the trailing arm with the subframe and insert the bolt from the rear. Install the new nut without tightening it yet. Install the bracket for models with height sensors before installing the retaining nut. Ensure the ball joint studs and mounting holes are clean and dry. Move the trailing arm into position and engage the ball joint with the hub carrier. Press the inner ball joint stud into position if necessary. Install a new nut to the outer ball joint stud and tighten it to the specified torque. For models with suspension ride-height sensors, install the sensor link bracket to the trailing arm and secure the clamp. Raise the front suspension to simulate normal ride height and tighten the trailing arm inner bolt to the specified torque. Install the engine under-shield, the wheel, and lower the vehicle to the ground. Tighten the wheel bolts to the specified torque. For models with active steering, have the steering angle sensor calibration carried out using BMW diagnostic equipment. It is recommended to check the front wheel alignment at the earliest opportunity.