Thrust arm (front control arm) bushing is a common failure on F10 BMW xDrive cars but luckily BMW made the thrust arm replacement a straightforward process. The thrust arm bushing can be replaced without replacing the entire thrust arm as long as the ball joint is in good condition. I elected to replace the entire arm so I wouldn't have to deal with pressing out and pressing in the bushing.
Here is an example of a cracked thrust arm bushing. The symptom of a failed thrust arm bushing is looseness in the front end and squeaking when going over the speed bumps.
1. Remove the undercar shield.
2. There is not enough clearance to remove the thrust arm without moving the axle shaft slightly out of the way. Insert a socket extension into one of the lug bolts to prevent the hub from spinning and remove the axle shaft bolt.
3. Unscrew the thrust arm ball joint nut.
4. Remove the bolt that holds the thrust arm to the subframe. Move the axle slightly out of the way and remove the thrust arm. If the ball joint is stuck in the spindle a few taps with a hammer should pop it out. If it is really rusted on to the spindle an air hammer can be used to break the ball joint loose.
5. Install the new thrust arm but do not tighten the bolt that goes through the thrust arm bushing until the suspension is preloaded and is at the normal ride height. A preloaded bushing will fail prematurely. Use a new axle bolt and tighten the bolt to 155 ft-lbs of torque.