Ford Motor Company (USA) is recalling 8,800 full-size cars due to a potential front wheel bearing hub assembly failure. Ford's recall is 07S54. The NHTSA recall is 07V270000.

Involved are the Ford Crown Victoria, Lincoln Town Car, and Mercury Grand Marquis, all built on the same rear-drive Panther platform.

Ford's notification says: "In some of the affected vehicles, the front wheel bearing and hub assembly may fracture due to improper heat treatment. If a hub fractures, it may potentially detach from the wheel knuckle, resulting in the wheel being retained only by the brake caliper assembly. As a result, the wheel may separate from the vehicle, potentially resulting in a crash."

Adding more detail, Ford said: "Improper heat treatment of the front hub assemblies by the supplier may allow the development of a circumferential crack on the roll formed end of the hub assembly. This condition can result in axial movement of the wheel, causing front end noise and steering wheel shudder, and the potential for wheel separation and/or the loss of steering control."

The problem was first noted May 25 by Ford at the St. Thomas plant when one of its production cars exhibited noise on the Squeak and Rattle test drive. The car also, "exhibited excessive end play on the front left hand hub assembly." St. Thomas had the same problem crop up again on May 25 and yet again on May 29. It was then that the first circumferential crack was discovered.

The recall hits model year 2007 Town Cars built at the Wixom Assembly Plant (Michigan) between May 15 and June 5, 2007; model year 2008 Crown Victoria and Grand Marquis built at the St. Thomas Assembly Plant (Ontario, Canada) between May 16 and June 25, 2007.

Wixom, opened in 1957, was officially closed on May 31 after producing 6.6 million vehicles; the Ford recall's reference to Wixom production dates through June 5 is unexplained. Wixom closed as part of Ford's "Way Forward" restructuring; Town Car production will shift to St. Thomas and restart in fourth quarter 2007. The St. Thomas plant also inherits the Wixom-invented Town Car 12-inch stretch modification, accounting for 25 or more Town Cars each day.

Lincoln Town Car recalls qualify for Ford's "Special Handling Procedure" which was put in place in 2001 to help bolster Lincoln's customer service experience. Ford asks dealer support and cooperation to, "make this a positive experience for our Lincoln Town Car customers." And effective with model year 2008, the Crown Victoria became a fleet-only vehicle. Despite their relative invisibility in the marketplace, the three full-size cars sold almost 160,000 units in 2006.

SKF has been manufacturing the wheel bearing hub assemblies (Ford P/N 7W1Z-1104-A) for Lincoln / Mercury / Ford full-size cars since model year 2005. The unit is equipped with a sealed, integrated electronic ABS sensor and detachable signal cable. Other innovations address potential corrosion areas, such as using corrosion-protective paste on the flange face, where the brake rotor hat sits, and installing a protective sleeve to prevent galvanic corrosion between the steel wheel bearing and aluminum knuckle.

The hub bearing assemblies are produced in Glasgow, Kentucky. They had been produced in SKF Automotive's plant in Airasca, Italy, but Glasgow offers a more localized supply base for U.S. domestic automakers. SKF does not ship the finished wheel bearing hub units from Glasgow to Ford, but instead to a Tier 1 supplier who builds them into more complete "corner modules" by assembling the knuckle, bearing and several other components before shipping the ready-to-install module to Ford.

Once Ford discovered the failures during S&R drives at St. Thomas, SKF almost immediately determined the failed hub assemblies were heat treated on May 9, 2007. Ford said it originally believed the hubs were only installed into vehicles built between May 15, and May 30, 2007. However, a third failure was found on June 25 and two more came subsequent to those, for a total of five. All of the cracked hub assemblies had a build date of May 17, 2007 (Julian 137).

Pursuing the problem, Ford said SKF was, "not able to provide adequate process control information for the duration of the batch build that began May 9, 2007 and ended May 29, 2007. On June 29, 2007, the Field Review Committee approved a supplement to safety recall 07S54 that includes all vehicles possibly equipped with wheel hub assemblies produced in this batch build." Hence the recall field was expanded from 1,483 to 8,800 possible vehicles.

Because the full size Ford, Lincoln and Mercury are not manufactured in VIN number order, the recall is defined by vehicle production date rather than the more familiar VIN number sequence.