DETROIT — Ford Motor Co. hopes silence is indeed golden, having pulled out all the stops to reduce NVH in its refreshed '03 Expedition.
Along with more packaging refinement — and a couple of genuine surprise-and-delight features — the all-new Expedition thankfully tilts towards a higher dynamic standard with fully independent rear suspension and rack-and-pinion steering. It remains, however, a body-on-frame layout, say engineers, because unibody construction has yet to prove capable of passing Ford's ruggedness demands.
First, the quiet factor: Using hydraulic engine mounts and structural foam, the auto maker has reduced noise by more than four decibels compared with Expedition's '02 predecessor.
The decision to use expanding foam forced Ford to expand its Wayne, MI, assembly plant, where the auto maker also builds the Lincoln Navigator.
“We needed to put into the plant a means in which we could inject the structural foam,” NVH Supervisor Tim Mouch says, adding the foam's consistency is similar to peanut butter. “So we put in all-robotics applications to inject the foam. And that line is probably about a 300-ft. (91-m) addition.”
The result is an interior road noise reduction of 2 decibels. And, because Ford's brand of foam is denser after curing, it gives Expedition a 42% increase in torsional stiffness.
The increased density occurs because, unlike expanding foam developed for construction applications, the variety used for Expedition releases less gas as it hardens, Mouch says. Increased stiffness also reduces the number of annoying sounds, making Expedition less conducive to rattles and squeaks. The SUV's chassis — which is entirely new, “not one bolt” of comparison to the current F-150 chassis — is 70% stiffer, Ford adds.
The beast appears to sit lower because, for the most part, it does. Chief Engineer John Krafcik says the front bumper is a full 2 ins. (5 cm) lower than the previous Expedition, but a gradual rise means the height at the rear is almost identical. Step-in, meanwhile, is a more-comfortable 1 in. (2.5 cm) lower, but that's still a stretch for anyone too short to play high-school basketball.
A wind noise remedy involves the deployment of weather strips on the glass runs, which are twice as deep as those on '02 Expedition.
Meanwhile, the hydraulic engine mounts — two on the noise-improved but otherwise carryover 5.4L SOHC V-8 and one on the 4.6L base V-8 — reduce vibration.
“They're actually working as an active absorber for the vibrations,” Mouch says. “We're using the mass of the engine as a damper.”
The new Expedition also features two significant firsts for the segment — independent rear suspension (IRS) and a fold-flat third-row seat.
The IRS improves handling, but also reduces rear unsprung weight by 110 lbs. (50 kg) and six of the eight rear control arms are aluminum (the other two are high-strength steel). Engineers say, to our surprise, that the IRS system gives up nothing to the now-deposed but supposedly beefier solid-axle setup, but they admit, “The only thing is, it costs a lot more.”
Later, there will be an optional 4-wheel air-spring suspension.
Confusingly, there are two 4-wheel-drive systems. ControlTrac is basic 4WD improved with a dedicated controller and “surface detection” to enhance tractive effort. The optional AdvanceTrac — the only system that should be offered — adds electronic traction control to enable manipulation of torque from side-to-side as well as between front and rear.
Oh, and what about that pesky static stability factor that the National Highway Traffic Safety Admin. says forecasts a susceptibility to roll? An anticipated 3-star (out of 5) rating, say engineers, a one-star improvement (thanks, in no small fashion, to a 6-in. [15-cm] track increase).
The rack-and-pinion steering, by the way, reduced weight by 22 lbs. (10 kg) and cut friction by 19%. Brakes are said to be the biggest in the segment, which would be a welcome improvement, too. We'll hold court later on the chassis guys' assertion that the whole package actually is a hoot to drive — 'cause the current Expedition sure isn't.
That wonderful third-row seat folds flat with the (optional) touch of a button.
“We think that one touch of a button is going to surprise and delight,” says Ford Div. President Jim O'Connor. Meantime, there's more third-row legroom than offered by segment stalwart Chevrolet/GMC Suburban/Tahoe/Yukon.
More delightful, perhaps, is the 40/20/40 center row. That 20% section — perfectly sized for a child seat — ingeniously slides forward as much as 11 ins. (28 cm), which means Biff or Buffy can cozy up to a position just aft of the front-seat center console. This, says Krafcik, not only places the child within easier reach but also makes the safety-seated child feel more a part of the front-seat action.
Pricing is being withheld until just before launch in early spring or summer, the auto maker says. So are volume projections, which totaled nearly 180,000 units last year — a 16.6% decrease from 2000's tally of 213,483.
