2003 Expedition Chassis
Best on the Road
"The new Expedition delivers a driving experience that has never been available in a full-size sport utility. The steering is crisp and direct. The ride is plush yet controlled. The braking is strong. The Ford Expedition is designed to be an unqualified pleasure to drive."
’03 Ford Expedition Delivers Exceptional Ride and Handling
Four-wheel independent suspension and a number of new vehicle dynamics advances have enabled Ford engineers to dramatically improve the 2003 Expedition’s ride and handling, resulting in a SUV that drives like no other vehicle in its class.
The Expedition’s innovative new independent rear suspension (IRS) chassis architecture is the subject of five invention disclosures, including the breakthrough porthole-in-frame design. In fact, Ford Motor Company is the only manufacturer to offer a full-size sport utility with independent rear suspension. Among the advances in the new Expedition:
- Better control of wheel movement in all directions for enhanced response in tight maneuvers and over rough roads or uneven terrain.
- The widest track in the segment at 66.9 inches front and 67.2 inches rear provides enhanced stability and cornering control.
- Asymmetric suspension bushings that are softer longitudinally, for an improved ride, while firmer laterally, to maintain crisp handling.
- Air suspension, to be introduced during the model year, that will provide benefits both on- and off-road, including smoother ride, improved ingress and egress and increased ground clearance for rugged terrain.
- An all-new hydroformed frame design that is approximately 70 percent stiffer in torsion. The stiffer frame greatly reduces noise and vibration inside the vehicle and enables improved ride performance.
- The all-new variable-assist power rack-and-pinion steering is stiffer than the previous steering system, for better feel and control.
- Class-leading braking features four-wheel vented disc brakes that are 22 millimeters larger in front and 8 millimeters larger in rear than the brakes on the previous generation Expedition. A new Brake Assist feature that automatically boosts hydraulic braking pressure in an emergency situation helps greatly reduce stopping distances.
- Ford’s patented AdvanceTracÔ stability enhancement system automatically applies brake force to the individual wheel or wheels that will help control a skid or spin. The electronic traction control system has been optimized for off-road aggressiveness as well as on-road handling.
- A new quality control system at Michigan Truck Assembly Plant uses microelectronics to test each vehicle’s powertrain balance before it leaves the plant, improving quality.
Every System Plays a Part
Each component of the 2003 Expedition’s new chassis is designed to work with all the other pieces in an intensive systems approach to engineering.
Without the stiff new hydroformed frame – with 70 percent more torsional rigidity – engineers wouldn’t have been able to isolate the forces typical of rough pavement. Without the lightweight components of the new independent rear suspension which reduces unsprung mass by 110 pounds compared to the previous five-link axle they wouldn’t have been able to isolate the passenger compartment from roadway dips and rises.
The new 2003 Ford Expedition is the product of this combination of structural strength and engineering innovation.
Hydroformed Frame and Stiff Body Structure Provide the Foundation
The refined new Expedition – like its successful predecessor – uses body-on-frame construction for durability; it’s the only sport utility in its class able to survive Ford’s Tough Truck testing. Maximum towing capability is improved for 2003 to 8,900 pounds – up from 8,200 pounds in the previous model year.
The challenge to achieving good driving dynamics with a body-on-frame design is limiting unwanted flex. Hydroforming technology, a metalworking technique that uses hydraulic pressure to create bends without weakened stress points, helps to give the new Expedition’s frame a 70-percent improvement in torsional rigidity and 67 percent improvement in bending stiffness.
The hydroformed frame sections of the new Expedition are approximately 10 feet long, and run from just in front of the rear suspension to the front wheels.
Hydroforming uses hydraulic pressure at 17,400 pounds per square inch to expand tubular metal stock inside a mold. Due to the nature of hydraulics, all sides of the piece receive equal pressure, reducing the tendency for unwanted variations in thickness that can be caused by stamping. Instead, precise frame wall thicknesses are engineered into the design to handle specific demands. The frame on the 2003 Expedition utilizes components from 2 millimeters to 4.7 millimeters thick, matched to the specific loads at each location.
Because the wall thickness is more tightly controlled, the frame can be engineered with comparatively thinner metal overall and a larger cross-section. Much like designing a steel girder for a bridge, building a larger sectional area into the frame provides greater resistance to bending and twisting than a smaller frame of the same weight. The overall result is a frame that is torsionally stronger than possible under previous technology, without a severe weight penalty.
As another benefit, hydroforming these large frame sections eliminates 40 feet of weld lines and the overlapping material required to mate two C-channels. This offers additional advantages:
- Reducing the amount of welding reduces the chances of inconsistencies in the weld quality. This produces a more consistent frame section. This dimensional consistency allows engineers to be more precise in designing every component that attaches to the frame, and helps in analyzing the effect of dynamic forces that the frame and associated chassis parts will handle.
- Reducing welding also reduces the amount of heat applied to the frame during construction. Heat expands metal, and reducing welding time reduces heat-induced distortion. The result, again, is a more consistent frame that is built to tighter tolerances.
Cross-members pass through laser-cut holes in the frame rails and are welded at both the inner and outer faces of the frame rails. This design provides more resistance to bending and is more durable over the life of the vehicle than bolting, riveting or welding at one side only.
Frame Innovations Maximize Rear Suspension Capability
Front and rear sections of the frame are built of fully boxed sections welded from C-channel steel. This allows these frame sections to be replaced individually in case of crash damage.
In addition, the rear frame C-channel sections allow use of larger porthole cutouts for the rear axles. The vertical oval shapes cut into the rear frame rails make room for the axles to move further upward and downward as the independent rear suspension tracks uneven terrain.
"We were able to develop an independent rear suspension that has a full 9 inches of wheel travel. This was quite an accomplishment," says Matt Howard, chassis supervisor.
The portholes are reinforced with a steel tubular tunnel that provides exceptional strength and room for the half-shafts to move. The new design contributes to better response over large bumps and potholes, as well as improved off-roading capability. The engineering team responsible for this innovative packaging has earned five patents for their efforts.
"Nine inches is a huge amount of wheel travel for an independent rear suspension," Howard says. "This is obviously a benefit off-road, but also helps to keep the axles from bottoming out over big parking lot speed bumps or aggressively crowned intersections."
As a result of these frame design features, the key "nodal points" for dynamics engineers – the suspension mounts, engine mounts and body mounts – retain a more precise relationship to each other during every phase of vehicle operation. This allows a systematic approach to addressing the forces generated in all driving environments.
Atop the Frame, A Stiff Body
Expedition engineers also created a stiffer body shell. They compared the effect of adding steel braces at critical areas with results from a relatively new technology – structural foam. The foam produced far more improvement with less complexity and at lighter weight.
The new Expedition’s passenger compartment was designed with the industry’s largest application of lightweight structural foam.
Expedition engineers used structural foam in key areas such as the joints at the top of the B-pillars, at the top and bottom of the D-pillars, and in underbody channels. This helped to produce a passenger compartment that has 42 percent more torsional stiffness than that of the previous Expedition, which used no structural foam. The result? A quiet, rattle-free cabin.
"By limiting flex in the frame and body, we were able to isolate road and driving forces in the suspension," says Cj Lammers, driving dynamics team leader. "This greatly improves ride quality."
In addition to improved handling and quieter ride, the structural foam enhances crash safety.
Steering Provides Precise Control
Improved steering performance was a key engineering goal for the 2003 Expedition team. That’s why chassis engineers replaced the conventional recirculating-ball steering gear with a more precise rack-and-pinion design. But it wasn’t just a matter of bolting on new hardware. The entire steering system was subjected to intense scrutiny. As a result:
- The new steering system is twice as stiff as the previous recirculating ball design, for greater precision and accuracy. There’s no free play at the center of steering wheel travel.
- Friction is reduced by 19 percent. Steering wheel movements translate more easily into accurate steering response, better driver feedback from the steering system and reduced curb-to-curb turning diameter. New tie rod ends and ball joints use low-friction bearings. Wheel bearings come in a pre-loaded cartridge from the supplier, reducing lash.
- Steering system components weigh 22 pounds less than on the previous Expedition. This further improves response by reducing inertia within the system.
- Because of these changes, boost pressure could be reduced in the power assist steering, improving driving feel.
"Too much friction in the steering system can produce a heavy, sluggish feel," Lammers says. "It also gets in the way of the feedback that’s necessary to a spirited driving experience. You need connectivity – to be able to feel the forces the vehicle is generating during cornering. That’s the result we’ve tried to capture with the new 2003 Expedition."
Dynamics Enhanced by Architecture
Suspension architecture also contributes to the new Expedition’s feeling of stability and responsiveness. Roll center height and roll stiffness are among measurements that help to define these handling characteristics.
A vehicle’s roll center can be considered its "dynamic" center of gravity – the height of the front-to-rear axis around which it will lean under side-to-side forces. The higher the roll center, the more leaning forces are generated. Roll stiffness measures the suspension’s mechanical resistance to these leaning forces.
Roll center height is based in part on the location of the center of each wheel, so it changes as the wheels move through their range of travel in response to the road surface.
Both front and rear roll centers are designed to move at the same rate, although the rear roll center is slightly higher at normal loading. Roll centers for the new Expedition are 2.3 inches (58 millimeters) lower in front and 8.3 inches (210 millimeters) lower in the rear than those of the previous Expedition, due to the new suspension designs.
The rear toe link design improves tracking during maneuvers by reducing the effect of roll on steering geometry. A robust cross-member that runs from the left to right rear control arm mounts helps to reduce frame flex, further enhancing suspension stability.
Overall roll stiffness – the suspension’s resistance to body lean – was increased 50 percent from the previous Expedition. This provides better cornering stability and more agile handling.
Another innovation of the new Expedition’s independent rear suspension design deals with the forces generated by engine torque. The new rear differential mounting design is able to completely balance torque forces from the drive shaft and output shafts, for "zero roll" geometry.
This helps to reduce halfshaft and CV joint angles under roll, to reduce any chance of binding and to increase durability. To reduce road vibrations transmitted to the passenger compartment, the differential is mounted to a cross-member designed with a large cross-section. A longitudinal torque arm runs from the differential to a separate cross-member further forward, improving driveline smoothness and enhancing performance under strong acceleration. The differential cover is made of structurally ribbed cast aluminum for added stiffness with lighter weight.
Suspension Smoothes the Bumps
While the right amount of steering feedback is good, the same isn’t true of the jolts and harshness of rough pavement and potholes. The 2003 Expedition’s engineered frame stiffness and dimensional consistency work with its fully independent suspension to deliver a quiet, comfortable ride.
From an engineering perspective, any piece of structural metal is in effect a spring. The only question is its stiffness – how far it will deflect for a given load.
By designing girder-like stiffness into the Expedition frame, engineers are able to use other, purpose-built springs to handle specific tasks, such as smoothing out the effects of road surface irregularities and isolating the passenger compartment from noise and vibration.
For example, all of the suspension mounting points on the frame are very robust and rigid to provide a strong base for the fully independent coil-over-shock, double wishbone suspension system. Likewise, the engine mounting location is reinforced so that the hydraulic engine mounts can do their job of absorbing powertrain vibrations.
The 2003 Expedition uses a rugged double wishbone suspension both front and rear. The rear suspension lower control arm is an offset A-arm design, to uncouple ride tuning from handling tuning. This architecture channels jarring road forces into the rear control arm bushings. Those bushings are engineered to be soft in the vertical direction, to soak up bumps before they can reach the frame.
This is accomplished by casting voids – oblong-shaped holes – into certain sides of specific bushings. These holes in effect provide thinner, softer rubber walls that "give" under pressure and allow the wheels to momentarily move backward – recess – in response to a sharp jolt, such as a raised pavement seam.
Plush vehicles tend to have low wheel recession rates, which means they provide less resistance to rearward movement. But making bushings too soft overall can allow too much lateral – side-to-side – movement. Limiting lateral movement is key to achieving precise handling.
Expedition’s engineers designed the bushings with asymmetric qualities, including metal reinforcements molded into the rubber in some cases, so that they remain firm in the areas that receive steering forces. The bushings are indexed so that they can only be assembled in the correct orientation.
As a result, lateral compliance – movement – in the front suspension is considerably reduced. Under a representative 0.5-g side load, compliance is 1.7 millimeters at the wheel center, compared with 3.4 millimeters in the previous model – a 50-percent improvement. The rear suspension is five times stiffer laterally than the previous live axle design.
Expedition engineers also designed a so-called "grippy" bushing for the front and rear stabilizer bars. In this design, a flat area is forged into the stabilizer bar at its mounting points to match an oval-shaped bushing that holds the bar from turning. This provides quicker side-to-side response to cornering forces and reduces body lean in cornering while sharpening steering responsiveness.
The stabilizer bar end links use ball-type joints, to further reduce friction and enhance response.
During the model year, Expedition will be offered with optional four-wheel load-leveling air suspension that uses air springs in place of the standard coil springs. The previous generation air suspension used air springs on the rear axle only, with high-pressure air shock absorbers on the front.
The new air springs will be matched with Bilstein monotube shock absorbers. The combination provides the Expedition with unprecedented ride comfort.
Air springs provide a progressive resistance to suspension movement, so they can be tuned to provide optimum resistance. For example, the 2003 Expedition’s air springs have very low resistance to the first inch or so of suspension movement, which allows the suspension to react more quickly to small road surface imperfections. For this critical area of suspension travel, the air springs are softer than traditional coil springs. Beyond that point, the air springs provide higher resistance to prevent bottoming out.
The Bilstein shocks contribute to the enhanced ride quality because their monotube design allows use of a larger hydraulic piston, which provides more flexibility in tuning response to suspension movement than a conventional twin-tube design. This means suspension movement can be more precisely controlled in all conditions, improving both highway ride and off-road performance.
For ease of ingress and egress, the air suspension automatically lowers the vehicle approximately one inch when the transmission is shifted into park and the ignition is turned off. When four-wheel drive low range is engaged, the suspension automatically lifts one inch for increased ground clearance.
Ride height sensors automatically adjust pressure in the rear air springs to compensate for loading, such as heavy cargo in the rear of the vehicle, or towing. This keeps the vehicle level front-to-rear and maintains correct suspension geometry throughout the range of loading levels.
Independent Rear Suspension and Extensive Aluminum Usage Reduces Unsprung Mass for a Better Ride
"Unsprung mass," the parts of the vehicle that move up and down as the suspension compresses and extends, is a key factor influencing suspension response. The heavier a suspension component, the more likely it is to resist motion initially in response to a change in the road surface – and the longer it tends to remain in motion after the irregularity has passed.
The new Expedition’s fully independent rear suspension reduces unsprung mass by 110 pounds compared with the live axle design used previously.
"Every automaker has to deal with the same law of physics – force equals mass times acceleration," Howard notes. "Less mass means less force. Our competitors’ live axle designs have a huge unsprung weight disadvantage."
The chassis engineer’s goal is for the suspension to allow the tires to precisely track the road surface, for ride and handling benefits, and absorb the forces it generates before they reach the frame, for improved NVH.
That’s why six of the eight control arms on the Expedition’s fully independent suspension are made of lightweight aluminum. The final two – the upper control arms for the front wheels – are made of forged, thin cross-section steel.
While aluminum components are lighter than steel units of the same strength, they are larger and thicker. Using steel in these front upper control arms allows room for packaging the coil-over-shock system in both two-wheel-drive and four-wheel-drive configurations. Previously, four-wheel-drive Expeditions had front torsion-bar springs to allow clearance for the half-shafts.
The new common design reduces complexity while enhancing ride comfort in four-wheel-drive models. Another benefit is reducing front ride height by nearly 2 inches for four-wheel-drive vehicles, at the same time overall ground clearance actually increases by a half-inch.
The front steering knuckles also are made of aluminum, for weight savings.
Another key area where engineers turned to aluminum is the cover of the rear differential. The Expedition’s 5.4-liter engine uses a robust ring gear that is 9.75 inches in diameter; the rear cover serves as a structural "bridge" across the large differential housing and between the two mounting points to the frame cross-member. That’s why it’s made of ribbed cast aluminum, for strength and dimensional stability without the added weight.
All told, the Expedition uses 623 pounds of aluminum and 35 pounds of magnesium, more lightweight material than any other full-size sport utility.
Body Mounts Isolate Passenger Compartment
Body mounts likewise were the subject of careful engineering innovation. These mounts – 10 in all – serve to isolate the passenger compartment from vibrations that reach the frame.
The front and rear mounts on both sides of the main passenger cabin are built with a "shear" design. The basic concept is that of two concentric tubes, one bolted to the frame, the other bolted to the body structure. Rubber is bonded between the two tubes.
By surrounding the rubber bushings entirely with metal, these shear-style body mounts spread forces across the entire bushing surface, contributing to more consistent long-term performance by the rubber and protecting it from deterioration.
"My goal was to make sure that the body mount response remained consistent over the entire life of the vehicle," says Howard, who patented the unique mounting system that makes the rear body mount possible.
The metal tubes also serve a crucial function in improving crash performance by limiting fore and aft movement of the passenger compartment.
The two center body mounts on each side of the passenger compartment were built with a new "cup" style design that is similar to the shear mounts in that it surrounds the rubber bushing material with a metal ring to protect it and better distribute forces. Unlike the front and rear "shear" mounts, the two center mounts are designed exclusively to isolate the passenger compartment from vertical vibrations.
The final two body mounts are located on either side of the radiator housing. They are a more conventional solid rubber design, due to the less stringent demands placed on them.
Body and engine mount designs were computer designed, but then subjected to repeated evaluation to make sure they achieved the team’s goal: a quiet cabin.
The science involved in crafting a quiet ride relies in part on precise measurements of sound at the "driver’s ear" using sensitive microphones. But it also involves three-axis micro-accelerometers attached to the driver’s seat track that monitor any movement that may be transmitted to the driver.
Computer tools include three-dimensional representations of the frame, powertrain, suspension and body, which can be run through deflection simulations that exaggerate actual movements by a factor of 50, to reveal areas that may need attention.
"We were evaluating a great many options at a time," Howard says. "The only way to do this is with CAE – computer-aided engineering. It allowed us to weigh all the options before we actually built the designs and subjected them to instrumented testing."
All-new Brake System Delivers Improved Stopping Performance
One place where weight was increased for a direct customer benefit is in the Expedition’s brakes. The steel rotors are larger and thicker and the calipers are larger and even more robust – with 100-percent greater torsional stiffness – for enhanced stopping power and better brake pedal "feel" as the semi-metallic brake pads grip the rotors.
The pads are made of a semi-metallic lining material that offers a higher, 0.41-mu friction rating that provides increased stopping power. By going to a higher friction pad, engineers were able to fine-tune pedal feel by tailoring boost from the power brakes in two stages. This provides a linear stopping rate that is proportional to the amount of pedal force being applied.
The ventilated front rotors, which are gripped by twin-piston calipers, are 330 millimeters (13 inches) in diameter, an increase of 22 millimeters (0.87 inches), or nearly 10 percent. The ventilated rear rotors, with single-piston calipers that are finned to dissipate heat, have a diameter of 342 millimeters (13.5 inches), an increase of 8 millimeters (0.31 inches). Increasing rotor size provides more surface area for brake pad contact and better dissipates heat for more consistent braking performance in stop-and-go driving. Total swept area is now 512 square centimeters in front and 331 square centimeters in the rear.
Electronic controls enhance the performance of these mechanical braking systems. For example, electronic brake force distribution (EBD) uses data measured by sensors to compare wheel speed 50 times during each rotation. If wheel lockup is imminent, the EBD controller is able to redirect brake force within 7 milliseconds to optimize available traction.
A new Brake Assist braking feature reads the speed and distance of brake pedal travel. If the system determines that the driver intends to make a rapid stop – even if the pedal isn’t fully depressed – it boosts hydraulic braking pressure automatically. This can reduce stopping distances by as much as 20 percent.
The available AdvanceTracÔ electronic stability control system helps the driver to maintain control in extreme conditions by modulating the brakes to reduce the likelihood of a skid or spin during cornering. Sensors measure vehicle response compared with steering input, and the AdvanceTrac computer applies braking to the appropriate wheels and reduces engine torque as necessary to maintain control.
For example, if AdvanceTrac detects an understeer condition, where the vehicle isn’t turning as quickly as desired, it applies braking to the rear wheel on the inside of the curve, while reducing engine power. If the vehicle is oversteering, where it develops too much turning movement, the system applies braking to the outside front wheel to slow the turn.
Suspension Design Increases Braking Stability
The new independent rear suspension also contributes to confident braking feel. Under hard braking, the anti-lift geometry designed into the suspension reduces forward weight transfer by 400 percent, significantly reducing pitching forward under heavy braking, and improving driver confidence. This is achieved by keeping the suspension pivot point above the center of braking force, allowing Expedition to deliver 71 percent anti-lift.
This is carefully matched with 52 percent anti-squat, which keeps the rear suspension from lowering under hard acceleration. Allowing too much lift and dive in response to dynamic forces can produce an uncomfortable pitching motion while accelerating and braking.
The front suspension is designed to counteract any tendency for the front wheels to toe-out during any brake-induced body dive – the tendency for the nose of the vehicle to be forced downward during hard braking. The right amount of toe-out is good, because it provides a controllable level of understeer in off-throttle conditions, such as when the vehicle has approached a corner at too high a speed.
However, too much toe change can cause bump-steer – or unexpected direction changes – if one front wheel encounters a pothole or other sudden road surface irregularity.
The Ford engineers have designed in a small amount of toe-in under braking to counteract most of the natural toe-out forces, leaving only enough to provide the right balance of understeer and braking directional control for additional safety. The net result is minimal geometry change during braking.
The front suspension is designed with greater wheel offset – 44 millimeters versus 14 millimeters in the previous design. Offset is the distance between the wheel centerline and the inside face of the wheel, where it mounts to the hub.
Increasing the wheel offset places the brake deeper inside the wheel, which reduces scrub radius – the the distance between the tire patch center and the steering pivot. Reducing the scrub radius reduces leverage on the steering pivot applied by road forces, reducing the chance of bump-induced steering and negative feedback through the steering system from rough road surfaces.
Compared with the previous generation Expedition, the 2003 model has a dramatically decreased scrub radius – 11 millimeters versus 54 millimeters.
End-of-Line Vibration Analyzer Aids Quality
The same technology that helps dynamics engineers to evaluate ride quality is being applied to quality control in the assembly plant.
A new end-of-line vibration analysis system – first installed at Michigan Truck Plant where Expedition is built and now being rolled out in all Ford Motor Company assembly plants – give all drivetrain components a sophisticated final checkup before the vehicle is approved to ship from the factory.
This is a Consumer Driven 6-Sigma quality initiative that already is paying off with quality improvements and reduced customer complaints on current Expedition vehicles.
In the first 10 months of operation, the end-of-line vibration analysis program has reduced consumer complaints by 80 percent.
Each vehicle that rolls off the assembly line is tested. The system works by monitoring minute vibrations in the sheet metal using a three-axis micro-accelerometer as the engine is started and the vehicle is run through a battery of tests on a set of floor-mounted rollers.
The analyzer works by comparing vibration levels at a host of frequencies, extending well below the range of normal human hearing, with standards for each individual frequency. Those standards are developed based on the patterns developed for each model vehicle. If any reading extends beyond its allotted "window," it signals a specific problem.
The micro-accelerometer attaches to the vehicle’s roof automatically. The data it collects is analyzed by a computer program using mathematical algorithms and generates a report on the areas most frequently subject to quality control problems.
For example, the vibration analyzer can spot if a single wheel is improperly balanced. A wheel imbalance can translate into road noise or vibration. The system can also catch an unbalanced or misaligned driveshaft or underinflated tire, among other key areas.
Four-wheel-drive and two-wheel-drive vehicles have their own key areas of concern, and the vibration analyzer examines all of those areas.
Vibration analysis takes place during roller testing, which already was part of the quality control system, so it doesn’t add any time to the process. The report on each vehicle becomes part of its final paperwork. It must receive a passing grade in order to leave the plant.
Vibration analyzers already have been installed in the Harley-Davidson F-150 assembly line, and a hand-held version is being developed for dealer service.
As a dealer service tool, the analyzer will help service technicians to find and fix noise or vibration problems the first time. Noise and vibration annoyances are notoriously difficult for a customer to describe, leading to frustration on both sides. This pinpoints not only the probable cause, but suggests a specific solution.
Other plants that will receive the equipment include Norfolk, Va.; Wixom, Mich.; Kansas City, Mo.; and Oakville, Ont.
PROFILE
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Cj Lammers, vehicle dynamics team leader
The first thing you notice about Cj Lammers is his first name: Big C, little j, no periods. Credit his creative parents.
The second thing is his necktie. In a corporate casual environment, Lammers is almost never without a tie. But somehow it never comes across as formal. That’s because it’s usually the necktie equivalent of a Hawaiian shirt – colorful images of animals or racecars are common.
Behind the neckwear is his own exuberance. "I love to play and coach soccer – I helped start the Ford Soccer Club," Lammers says. "When I jump into something, it’s always with both feet. I took up mountain biking and about four months later I was biking Moab, Utah – and I got my butt kicked! But it was great!"
Lammers and his friends explore all the extreme sports they can get their hands on – mountain climbing, sky diving, whitewater rafting, open water kayaking, scuba diving – even Carnival in Rio de Janeiro, Brazil.
His exuberance extends to the auto industry. As an 11-year-old, he knew upcoming vehicle programs by their code names. After earning his master of science degree, he came to Detroit to turn his passion into a profession.
He avidly follows Formula One and World Rally. As a driving enthusiast, his tastes lean toward sports cars; he currently owns a Mazda Miata and Ford Probe GT.
Put him down for a bright yellow RX8 when they hit the dealerships.
Best in Snow, Best in Dirt
"This is the most capable Expedition ever. Others in its class can't make it out of the muck that Expedition chugs through. The qualities that keep the new Expedition from bogging down in deep sand, mud, and snow give its drivers a vast reserve of performance in daily driving."
Dana Katinas, off-road vehicle supervisor
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4x4 Expedition Gets Out of the Slipperiest Predicaments
The all-new 2003 Ford Expedition has a versatile, refined four-wheel-drive system and tenacious tractive ability in loose terrain, raising the bar for off-road performance by a full-size sport utility. Improvements to the ControlTrac™ four-wheel-drive system work directly with chassis improvements and the independent rear suspension. Advances in the new Expedition's off-road package include:
- Sophisticated new electronics allow more precise traction control to deliver torque to the wheels that have traction. The optional AdvanceTrac™ system adds the most sophisticated electronic traction control in the class to regulate side-to-side torque distribution better than traditional mechanical systems. Even challenging terrain that raises two wheels completely off the ground won't halt forward progress.
- For the first time, Expedition uses a standalone electronic processor to control its ControlTracä four-wheel-drive system. The system responds more precisely by processing more information, more quickly.
- ControlTrac's "surface detection" predictive technology anticipates and prevents wheel slippage in low-traction conditions by monitoring the driver's intent. The result is more seamless, confident performance.
- The 4x4 Expedition's dedicated two-wheel-drive mode allows quieter, more fuel-efficient operation on pavement. When selected, the system disengages the front driveshaft, differential and half-shafts. This reduces wear and tear, operating noise and drag, contributing to fuel savings. This feature was added in response to consumer requests. Expedition's transfer case is made of magnesium, rather than aluminum - a savings of approximately 11 pounds - for further fuel economy benefits.
- Expedition's electronic traction control system allows the driver to turn off the engine power management system for extreme off-road situations, so full engine power is on tap when needed.
- A new XLT option, the FX4 off-road model package, includes skid-plate protection and many features off-road enthusiasts most desire.
Dynamic 4x4 System Tailors Traction to Any Situation
Engineers for the new 2003 Ford Expedition had two goals when they designed the ControlTrac™ four-wheel-drive system: Class-leading off-road traction management and unprecedented refinement in everyday driving situations.
The path to both goals was the same - package a heavy-duty, all-independent coil-over-shock, double wishbone suspension with a new four-wheel-drive system that continually provides optimum performance in all conditions.
Electronics Improve System Response
The challenge for a full-size sport utility is to offer both refined road manners and the ability to tackle virtually all off-road conditions. Enhanced electronics, combined with the sophisticated fully independent suspension, help make this possible in the new 2003 Ford Expedition.
For the first time, a stand-alone electronic processor controls Expedition's four-wheel-drive system. The controller has far more memory, capacity and speed than previous systems, allowing engineers to program it with advanced algorithms that analyze data from more than a half-dozen sensors many times per second. Even before wheelspin begins, Expedition's new electronic controller can engage the transfer case to split torque front-to-rear.
The available AdvanceTrac™ option adds electronic traction control, which represents a significant advantage over mechanical all-wheel-drive systems. Expedition's traction control system applies braking selectively when it detects wheelspin. By stopping the spinning wheel, the system sends torque to the wheel that has traction.
The system takes advantage of the strengths of a traditional differential, rather than trying to change its nature with mechanical limited-slip devices.
By modulating side-to-side torque using the brakes, the four-wheel-drive system can transfer more total torque than most mechanical limited-slip systems to the wheel that has the best grip. Brake-based traction control also eliminates wear of expensive limited-slip devices.
Unlike purely mechanical systems, AdvanceTrac™ can keep the new Expedition moving forward even if two wheels are completely off the ground. In such extreme situations, most competitive vehicles would simply spin their wheels.
"We're able to climb hills that we couldn't climb before," says 4x4 specialist Peter Barrette.
Another benefit is exceptionally smooth, quiet operation - particularly under high throttle, where some systems can become very noisy and intrusive.
The electronic controller continuously monitors data from speed sensors on all four wheels. It then adds data about steering wheel position, to determine the intended direction of travel, and throttle position, to determine intended speed.
Previously, the controller only compared traction data gathered within the transfer case, which only allowed it to measure comparative driveshaft speeds - a rougher average of front-to-rear traction.
Now, when it senses wheel slip - such as when the driver suddenly applies full throttle on a loose surface - it can preemptively lock up the transfer case to send torque to both front and rear wheels.
The four-wheel-drive team worked very closely with engineers developing the new AdvanceTrac™ interactive vehicle dynamics system, since both teams were concerned with traction at the limits of performance.
The new traction control system also recognizes the need to reduce overall engine power in some driving situations and the need to have full power available for others.
On ice, for example, it's useful to reduce engine power to prevent wheelspin. However, momentum is the key factor in certain off-road situations, such as hill-climbing or traversing deep snow or sand. Without it, a vehicle could get stuck halfway up a hill or midway through soft terrain.
"You have to be able to tap that power when you need it," Barrette says. "When you don't want engine management, our system will let you shut it off manually. This is a plus for truly extreme off-roading."
ControlTracTM Offers More Choices
The Expedition's all-new ControlTrac™ system provides four settings for maximum flexibility. They are selectable through a rotary switch on the instrument panel, to the driver's right. Competitors' AWD systems (primarily in luxury SUVs and car-derived crossovers) lack the flexibility and capability of Expedition's new ControlTrac™ system.
2H
Reintroduced for 2003, a 2H mode offers maximum economy for highway driving. It was added in response to customer requests.
In 2H mode, the clutch and drive chain inside the magnesium transfer case are disengaged, saving wear and reducing drag. At the same time, all-new integrated wheel ends - an industry first - disconnect the front drivetrain at the wheel hubs to avoid "back driving" the front half shafts, differential and driveshaft.
The new integrated wheel-end units uncouple the front half shafts at the wheel hubs and are packaged inside the wheel hub housing for protection from rocks and debris.
The system is vacuum-operated. In two-wheel drive mode, a vacuum switch withdraws the clutch ring from the wheel hub coupler, allowing the system to freewheel. In all four-wheel-drive modes, the vacuum is shut off, the clutch ring engages the coupler, and the wheel ends lock the connection between the axles and hub.
The fail-safe default is to engage the system, allowing normal four-wheel drive operation. This system is both more convenient and more compact than manual locking hubs.
A4WD
The A4WD mode is an "active" system, in which the four-wheel drive controller continuously monitors wheel slip and vehicle response, to tailor traction to the driving environment.
This is the setting most appropriate for a mix of driving conditions, as it offers the transparency of two-wheel drive on pavement and sophisticated four-wheel drive capabilities in slippery or off-road conditions.
An exclusive "surface detection" program in the controller allows it to recognize the amount of grip available. When the wheel-speed data indicates the Expedition is on pavement, it turns off pre-emptive traction strategies. This eliminates binding in tight turns, such as parking lot maneuvers, where all four wheels would naturally turn at different speeds.
However, when it detects a slippery or loose surface, it allows the transfer case clutch to engage earlier - sending torque to both axles if the driver suddenly accelerates, for example.
"Because we can infer driver intent, we can send torque to the front wheels before slip occurs," says Barrette. "We get better traction, more smoothly, and only when it's needed."
4H and 4L
Both 4H and 4L settings mechanically lock the transfer case, to continually apportion power to both the front and rear axles. The 4L setting adds a mechanical gear reduction within the transfer case to increase low-speed torque.
These settings are meant for extended or extreme off-roading. The 4L setting also is useful when extra torque is needed in limited-traction situations, such as pulling a heavy boat up a slippery launch ramp. It also offers additional engine braking, which is useful when descending a steep hill.
The robust differential is available with an 8.8-inch ring gear or an optional 9.75-inch gear that is largest in the class. These heavy-duty components are designed to handle the engine's power in extreme off-road and towing conditions while allowing the differential to spin slower under normal operations for fuel savings.
The electronic traction control system continues to operate in 4H and 4L, a segment-exclusive, transferring torque side-to-side. In 4L, the engine intervention function is automatically turned off, to preserve full torque capability, while braking intervention remains enabled to provide side-to-side torque transfer. The driver can turn off engine intervention in any mode using a dash-mounted switch, if desired.
Chassis Handles Off-Road Demands
The new Expedition uses a purpose-built, more civilized version of the type of coil-over-shock, double wishbone suspension found on desert race machines. The heavy-duty upper and lower control arms are built to withstand severe use, while the new hydroformed frame and stiffened passenger compartment resist inputs from uneven terrain.
As a new feature this model year, the Expedition's frame is electro-coated for durability. This offers corrosion protection that won't rub off in heavy use, as wax coatings might. The frame walls are designed to be thick enough to resist dents from rocks and off-road debris, and to offer a sturdy surface for jacking in case of a flat tire.
The 2003 Expedition features an extra half-inch of ground clearance compared to the previous model, to better hurdle obstacles. Ground clearance to the bottom of the rear differential is up substantially - to 10.5 inches.
The new porthole-in-frame design of the rear suspension, with vertical oblong cutouts, allows nine inches of total wheel travel. This is a derivative of the innovative porthole-in-frame design pioneered on the 2002 Ford Explorer.
Wheel travel is important as it helps to keep the tires in contact with uneven terrain, and to soak up jarring impacts. The new Expedition also offers better damping at the extremes of axle travel due to new, progressive jounce bumpers.
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The dramatically reduced unsprung mass of the new independent rear suspension also helps the Expedition's terrain-following capability.
Virtually 50/50 weight distribution helps distribute traction to all four wheels. Although the new chassis design allows more length in front and rear crush zones for safety, the Expedition maintains good approach and departure angles, for handling steep terrain.
Off-road enthusiasts will appreciate the Expedition team's attention to packaging various components out of harm's way. For example, the exhaust system and engine fan are secured closer to the vehicle so they're less susceptible to off-road debris.
Wheels and Tires
Wheels and tires play an important part in off-road traction capability. For 2003, the all-new Expedition gets larger standard wheels - 17-inch compared with 16-inch previously. The wheels are 7.5 inches wide, and attach with six conical lugs, rather than five in the past, enhancing durability.
The change to a larger standard wheel also offers several performance benefits. Brakes are larger than in the past, for improved braking, and the larger tires contribute to improved ground clearance.
Four-wheel drive Expeditions get a new 265/70R17 Continental All-Terrain tire, with outline white letters (XLT value models excluded). This tire offers an aggressive tread for improved traction on soft surfaces.
On two-wheel drive models, a 265/70R17 Continental All-Season tire is standard, with black sidewalls on XLT and outline white letters optional on XLT and standard on Eddie Bauer.
All tires are specified for operation at 35 pounds per square inch of inflation pressure.
Both aluminum and steel wheels are available, depending on the trim level. The Eddie Bauer model has five-spoke machined aluminum wheels with contrasting satin inserts. XLT models use a split-spoke design - five sets of double spokes painted sparkle silver. Base models feature a 5-spoke stamped steel wheel.
"We deliberately went to five-spoke chromed steel wheels for the FX4 package," says Dan McCarrick, tire and wheel specialist. "Steel wheels won't crack if you really nail a sharp-edged rock. They're less stiff and more resilient. If you're miles from nowhere and the wheel bends, you can literally hammer it back into shape in the field."
FX4 is Trail-Ready
In addition to durable chromed five-spoke wheels, Expedition's new FX4 package for 2003 includes protective, performance, and appearance additions.
A set of skid plates helps protect the engine and oil pan, transfer case and fuel tank. The front skid plate is a bright-finished galvanized steel, featuring the Ford oval. The skid plate over the transfer case is electro-coated galvanized steel, while the fuel tank is protected by lightweight fiber-reinforced plastic.
The skid plates are easily removable for service. Supplying them as a factory option offers convenience, peace-of-mind, and assures that they fit properly.
FX4 shocks are tuned to meet the demands of serious off-roading and are finished in red for a more aggressive appearance. Shock tuning makes a tremendous difference in both ride comfort and body control at the extremes of performance. These twin-tube shocks offer more progressive damping against large inputs during heavy off-roading.
The FX4 package includes a limited-slip 3.73:1 rear axle as standard equipment for better traction and more ability to use torque from the powerful 5.4-liter Triton™ V-8. The optional AdvanceTrac™ system replaces the mechanical limited slip function with electronic traction control and a standard 3.73:1 differential.
Fog lamps and tubular steel running boards are included. A new FX4 badge on the right rear portion of the liftgate identifies this off-road package.
PROFILE
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Brent Smith, braking and traction specialist
Brent Smith knows all about braking and traction - they're knife-edge realities when he's racing his go-kart at tracks around the country.
But while the racer in him must depend on the exquisite sensitivity of his braking foot, the engineer in him is applying advanced electronics to braking, interactive vehicle dynamics and traction control on the new 2003 Ford Expedition.
Smith, an Illinois native, began his career with Ford Motor Company about six years ago as a college student, working in brake development while earning his master's degree in mechanical engineering.
For the past two years, he's been helping to fine-tune the systems that analyze vehicle motion and, if necessary, intervene to help the driver to maintain control in crucial situations. The Expedition's electronic brains can modulate its brakes singly, in pairs or all at once as necessary - all tailored to the individual situation.
Outside work, Smith and his wife, Cassandra, rescue Siberian Huskies such as Babe (left) and other breeds as volunteers for the Michigan Humane Society. Smith also helps Cassandra's first-grade students with their class projects, and volunteers as a chaperone for field trips.