**Referred to as a ball joint by BMW, pressed into the rear wheel carrier, attaches the rear camber link to the rear wheel carrier** This bushing is pressed into the rear wheel carrier and acts as a mounting point for the rear suspension. Commonly this bushing/ball joint can develop a significant amount of play with high mileage causing handling and alignment issues. To test for play grab the rear wheel in the 3 and 9 o'clock position and try to move the wheel. If there is play this ball joint/bushing has failed.