The 2002 Thunderbird expresses a bold, confident and free feeling delivered in the form of a dramatically designed, two-seat, rear-wheel-drive, V-8-powered, convertible roadster – a modern throwback to another optimistic American era.

It comes standard as a convertible and offers an optional removable top with classic porthole windows. The removable top weighs 83 pounds for easy removal and installation. A secure pin-and-bolt system at the two front attachment points and two clamps at the rear connect the removable top to the car. The two-place interior reflects the exterior design and the car’s romantic heritage with bold style combined with the comfort and convenience today’s customers demand.

Thunderbird is in a class by itself as a 107.2-inch wheelbase rear-wheel drive roadster with a smooth, free-breathing 3.9-liter V-8 engine.

Weight distribution on the Thunderbird is nearly an ideal 50/50 front to back. Spreading the weight evenly across the wheels gives better overall balance across all four tire patches, eliminating the risk of both understeer and oversteer.

Powertrain
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For the new 2002 Thunderbird to be called a true American dream car, it would have to feature heart-throbbing V-8 power. But as a modern icon, it would have to be smooth-running power. The Thunderbird team found its answer in Ford Motor Company’s new 3.9-liter V-8 designed for the Lincoln LS.

The vehicle’s ride and handling are enhanced with the smooth, quiet all-aluminum 3.9-liter DOHC V-8. The engine delivers a combination of performance, durability, fuel economy and low emission vehicle (LEV) standards.

It generates 252 horsepower at 6,100 rpm and 267 ft. lbs. of torque at 4,300 rpm. It incorporates a lightweight drive shaft made from a high-strength steel tube with forged end flanges, using less material than equally functional conventional shafts. The engine features coil-on-plug ignition with platinum-tipped spark plugs, lightweight, low-friction pistons and dual exhaust.

The throaty exhaust sound – located on a tonal scale somewhere between a Mustang GT and a Lincoln LS – was carefully tuned to recapture some of the authentic Thunderbird magic. Engineers drove a 1955 Thunderbird to listen to its distinct tone and then set sound targets for the 2002 model. They adjusted pipe, muffler and resonator size and baffling to achieve the right note.

"Part of the overall driving experience in these cars is the subtle roar of the engine," says Scott Cooper, powertrain supervisor. "What you like to hear is a low-frequency, deep tone from the exhaust when you put your foot into it. It sounds good."

Three-inch-diameter tips at the ends of the tailpipes give a bright appearance from behind the vehicle. Small cutouts in the vehicle fascia around the tips help them stand out even more.

Mated to the engine is a five-speed, close-ratio electronically controlled transmission with an overdrive top gear. The transmission features a one-piece die-cast aluminum case for reduced weight and reduced powertrain bending characteristics.

A quiet gear set is used in the transmission to minimize first- and second-gear whine, and a 3.58:1 final drive ratio gives better performance feel.

Noise, vibration and harshness
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The Thunderbird noise, vibration and harshness team's challenge was to develop performance that delivers to the customer the promise of sportiness without compromising comfort. Accomplishing this goal meant eliminating unwanted noises and tuning preferred noises to the desired sound quality.

"The vehicle had to be quiet to provide comfort for long drives to the country, but it also had to provide sound feedback to ensure there is no mistaking the Thunderbird as a driver's car," says Ron Ziegler, noise, vibration and harshness supervisor.

The new cam drive system for the timing chain was incorporated to reduce chain whine. The drive line was balanced to eliminate unwanted engine moan. Engineers also used laser holography to map the floor-pan vibrations that result from driving. As a result, mastic was applied only where needed to reduce excess noise, saving cost and weight.

Sound quality listening studies were conducted using recorded and computer-generated sounds to establish preferred characteristics for exhaust and door-closing sounds.

"We allowed more of the exhaust sound through," Ziegler says. "We were able to produce a powerful exhaust note during acceleration without compromising quietness while cruising. This results in a vehicle that is relaxed and sporty at the same time."

The team in charge of noise, vibration and harshness on Thunderbird used a computer-aided-engineering technique called statistical energy analysis to understand convertible acoustics and build a balanced package. This allowed the team to develop a strategy for sound treatment even before hardware prototypes were available.

"The testing led directly to the decision to increase the density of the convertible top liner," says Ziegler. It also highlighted a need to look closely at the rear of the Thunderbird as a source of sound. Engineers added sealing and barrier material to reduce road noise.

Computer-aided engineering enabled NVH team members to rank the major sources of sound and predict where the most likely NVH trouble spots would be. "Then, we could attack the most significant sources directly without the trial and error of developing the hardware first," Ziegler says. "CAE not only helped identify significant sources to treat, it helped us to avoid overtreating insignificant sources. It allowed us to put a design in place and then optimize that design during development."

Top-down turbulence on the Thunderbird is reduced because of the steep angle of the windshield. With airflow visualization, engineers were able to ensure the wind crossing over the windshield doesn't create unwanted cabin turbulence that would interfere with conversation. The Thunderbird antenna is embedded in the windshield to reduce wind noise from whistling that can occur with an outside-mounted antenna.

Additional isolation from wind noise results from the doors' drop-glass feature. When the Thunderbird door is opened, the side glass lowers just slightly. When the door is closed, the glass goes back up to fit snugly into the seal system. At high speeds in many other convertibles, the glass can pull away from the seals and allow noise to seep in. But the Thunderbird sealing outside the glass reduces this risk and adds a barrier against water leakage.

Body and chassis structure
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With driving dynamics, everything begins with a solid foundation. Simply put, high body stiffness levels provide the basis for good ride and driving dynamics by providing a solid base for the suspension. Loss of stiffness means a less responsive suspension and more unwanted vibrations. Achieving the desired high levels of stiffness in convertibles presents a challenge, because the roof of a conventional coupe typically contributes to body stiffness.

The 2002 Thunderbird's stiffness, and resulting responsiveness, had to be built from below because it wouldn't have a roof.

Computer modeling, through a Ford system called C3P, identified potential areas that would benefit from added structural braces. One of the team's first moves was a cross-car beam just behind the seats that integrates into the structure. Next they added a series of three steel bolted-on X-braces; hardware not found in a typical sedan with a fixed roof structure.

One X-brace is below the engine compartment, where space is at a premium with the powertrain package, oil pan, oil filter and steering apparatus. By integrating the X-brace into the cross member for rack-and-pinion steering, the team preserved Thunderbird's optimum ground clearance.

The team also created a special midcar X-brace expanding it as far forward and backward as possible while taking special care to route the exhaust systems over it.

For the rear X-brace, engineers and manufacturing specialists worked together to meet the challenge of getting around such components as the hydraulic pump for the convertible top, a sling that houses the soft top when it's down and a number of electrical modules.

"We've been creative with these modules, and mounted them right on the brace," said Joe Williams, North American Car Vehicle Center supervisor. "We’ve put them together – instead of scattering them – for maximum effectiveness."

The rear brace, a 76-millimeter-diameter tube, is key to the car's stiffness. Bolt-on braces typically are added in the body shop, but Williams says the Thunderbird's very stiff rear brace is so critical to the body structure that it has to go on early in the assembly process. This helps ensure top quality and precision Thunderbird fits along the body.

On the front other smaller, tubular braces were put across the rear-wheel kick-up area and the steering-column bracket for stiffness. The steering-column brace also enhances steering feel. The rocker section also was specially designed to achieve the stiffness needed for the convertible Thunderbird. Reinforcement was added inside the section.