Related: Automotive Chassis
Ford's full-size "Panther" platform–a body-on-frame design that dates back to the first Bush administration–undergirds the Ford Crown Victoria, Mercury Grand Marquis, and Lincoln Town Car. These cars have been very profitable for the company, and have undergone both major and minor design and engineering changes over their lifetimes. For 2003, the Panther's chassis, suspension, steering, and brakes have been revised. The Town Car's body has been updated to reduce flex and noise, and to bring the styling more in line with Lincoln's new design theme. Meanwhile, Mercury has taken the chassis tweaks, added a more powerful engine, and firmer springs and dampers to re-create the Marauder.
The full-perimeter frame's front frame rails are hydroformed and fully boxed, which makes them lighter and stiffer than the welded, open-section stamped channels that had been used. These new frame rails are filled with structural foam in key areas to control crush, especially in offset frontal collisions. Behind them sits a cast aluminum crossmember that serves as the mounting surface for the new rack and pinion steering rack (previous Panthers used recirculating ball steering which was light but imprecise), front suspension control arms (stamped steel uppers and aluminum lowers), and engine mounts. As you might expect, it's a rather robust casting, but it's lighter than the previous steel unit, and–because it is a single casting and not a multi-piece welded structure–alignment tolerances are much tighter than before.
From A-pillar to A-pillar across the frame sits the new third crossmember, which retains the previous steel construction, but is stronger than before. It is designed to feed side impact forces to the opposite frame rail. "The front- and side-impact requirements drove the changes in the design of the frame," says Dr. Mike Renucci, director of Lincoln Mercury Engineering, "which gave us the opportunity to make some changes that increased the frame's stiffness while improving crash performance. It would have been tough to justify the expense of the cast aluminum crossmember without the need to meet the offset crash requirements." Frame torsional rigidity is up 24%, while resistance to bending improves 20%.
The variable-ratio rack and pinion steering system weighs an almost unbelievable 22.5 lb. less than the recirculating ball system it replaces, while adding a speed-sensitive variable-assist control module. On the Mercury Marauder it is fitted with travel stops due to this car's wider front tires, and it gets firmer tuning. Cast aluminum is used for the steering knuckle (which reduces weight a further 5 lb.), and a new intermediate shaft–called a "swing link"–reduces operating friction by 24%. The Marauder also gets a larger, 28-mm front anti-roll bar, and all Panther vehicles are fitted with bushings that can't twist under load, which makes the response rate of the steering more linear.
Monotube dampers are used front and rear, in union with coil springs in front and air springs in the back. The rear suspension is revised to allow the formerly staggered rear dampers to be mounted further outboard and nearly vertical. This greatly improves their ability to manage unsprung mass, and reduce ride harshness. By adopting this design, the engineers were able to increase the rear track by 14 mm. The Marauder uses the self-leveling air springs to retain its aggressive front-to-rear rake no matter the load.
The Town Car's braking system gets a new dual-rate brake booster that applies full braking power in a panic stop, even if the driver doesn't initially apply enough pressure to trigger the ABS system. (As Renucci is quick to point out when describing this feature, the average age of a Town Car buyer is 70.) Because the Marauder's DOHC V8 is wider than the Town Car's SOHC version, it receives a unique brake booster that better fits in the available space. In addition, the Panther platform's twin-piston front calipers are 16% stiffer. Single-piston calipers are used in the rear.
The Town Car's two-valve-per-cylinder, single overhead cam V8 produces 239 hp at 4,900 rpm, and 287 lb-ft of torque at 4,100. This is an increase of 19 hp and 22 lb-ft of torque over the 2002 model. In contrast, the Marauder's four-valve-per-cylinder, dual overhead cam V8 belts out 302 hp at 5,750 rpm, and 310 lb-ft of torque at 4,250 rpm. A higher stall-speed torque converter and 3.55:1 rear axle ratio lets the Marauder hit 60 mph from a stop in less than seven seconds, and run through the quarter-mile in less than 15 seconds. Not bad for a 4,165-lb. sedan. Asked about the Town Car's acceleration, Renucci describes it as "adequate."
Where the two cars really depart is in the body. The Town Car's body structure has a new laminated steel dash panel; an aluminum floor pan doubler welded in the front passenger footwell; a stronger instrument panel brace; thicker sound insulation in the wheelwells, roof, body pillars and doors; and new body and cowl air seals. As a result, the 2003 Town Car is almost eerily quiet, with wind noise around the larger side mirrors the major distraction. Renucci claims initial testing shows the Town Car to be quieter than the Lexus LS 430.
Up front, the Town Car gets Lincoln's new signature headlights–dual round lamps with a jeweled reflector per side–and a more upright and formal grille leading into a taller hood with a center spine and stand-up hood ornament. In back, the taillights frame a wider opening with straighter sides, and the rear fascia and license plate surround have been revised for a cleaner appearance.
In contrast, the Marauder gets unique headlamps with smoked lenses and blacked-out trim, a body color (gloss black) grille with chrome Mercury emblem (program manager Steve Babcock hopes to eventually replace the "waterfall" emblem with one showing the profile of the god Mercury), front fog lamps, unique 18-in. wheels with the "god's head" emblem on the center caps, smoked rear light clusters, the Marauder name stamped in the rear fascia, and 3.5-in. Megs exhaust tips. The latter attach to a high-flow stainless steel exhaust system.
In the future, the Panther platform may get an independent rear suspension and other tweaks, but a complete re-do is far off on the horizon. Ford makes a bunch of money off this platform already, plus its current financial situation makes any serious change cost prohibitive. Hopefully future revisions will be as successful.