I started having a problem with my Mustang last week. When I put it in reverse and backed to the left, it made a noise like the tire was rubbing. I took it to a garage and they determined it was a bad ball joint. The newer Mustang's do not have a grease fitting on the ball joints. I went to Advance Auto and bought a grease needle ($4.00). The grease needle is inserted into the rubber boot of the ball joint, and you fill it with grease. The pressure from the grease will fill the tiny hole made by the needle. Problem solved! And I did not have to buy new ball joints. If anyone else has the same problem, I hope this helps you.