Not flat enough
This bulletin applies to 2006-2011 Ford Fusion, 2006 Lincoln Zephyr and 2007-2011 Mercury MKZ and 2006-2011 Mercury Milan vehicles. Some vehicles may experience a single rear wheel stud fracture. The cause: Some vehicles were assembled using a wheel mounting face or rear brake rotor that was not flat.
Remove the rear wheels and clean the wheel mounting surfaces with a suitable wire brush. Position a machinist’s straightedge flat against the rear brake disc wheel mounting surface, with the side of the straightedge next to or touching the wheel hub.
Use a feeler gauge between the straightedge and mounting surface to check for flatness.
If a 0.025-inch feeler gauge cannot be inserted between the mounting surface and the straightedge, the rear brake disc is within specification. If a gap of 0.025-inch or greater is found, replace the rear brake disc.
If a fractured wheel stud is found, use special tool 204-592 or equivalent to remove the faulty stud. Using two large flat washers and a 12 mm x 1.50 nut, install the new stud into the wheel hub. Seat the new stud using 40-80 ft.-lbs. of torque on the nut. Do not install the stud using a power tool.
Remove the nut and flat washers and install the wheel, torquing nuts to 100 ft.-lbs.
9E5Z-2C026-B……rear disc brake