How to Change Struts on a BMW 323i

1. Loosen the lug nuts on the wheels, place the car on a set of jack stands at all four corners and remove the wheels. The rear jack can go at the control arm mounting point.
2. Disconnect the leveling sensor (if the car has Xenon headlights) to prevent damaging it during spring removal. This sensor is located on the passenger side behind the sway bar end-link and shock, and is held on with a 10-mm nut.
3. Disconnect the swaybar end-link with a 16-mm box wrench on the back and a 16-mm socket on the front. Push the end-link out of the way. Next disconnect the shock and the control arm with an 18-mm socket and an extension. You may need a breaker bar to get the bolt loose. Support the control arm when the bolt is removed with a box so the brake lines are not damaged. Remove the three 10-mm nuts at the top of the shock and pull out the shock and spring. Repeat on other side.
4. Move to the workbench or an open area to install the spring compressor to remove the spring from the shock assembly. Place the spring compressor hooks on either side of the spring and alternately compress each side until the hat at the top of the spring is loose. Use a 21-mm socket to remove the hat. Install new the shock and begin to loosen the spring compressor, taking care to properly seat the spring against the hat in the corresponding notches for the spring. Tighten the nut on the hat. Inspect everthing and then reinstall in the car.
5. Reinsert the control arm onto the shock body with a jack pushing up the control arm. Put the swaybar back on and reinsert the top three bolts for the strut. If applicable, reconnect the Xenon sensor.
6. Move on to the rear. Fold down the rear seats and remove the plastic tab underneath the leather or cloth trim. Remove the two plugs that allow access to the shock bolts. Place a jack on the control arm and jack up the shock a little until the tension is released. Remove the top bolt. Move to the bottom of the shock and remove the bolt there. The shock should now come out.
7. Install new shock and replace the bolts. When retightening the top bolts, make sure there is pressure on the shock. Hold the shock piston with a small wrench when you tighten this bolt.