Rushing to meet a production deadline a decade ago, Ford Motor Co. rejected major design changes that would have made its Explorer sport-utility vehicle less prone to rolling over, relying instead on smaller changes and reduced tire pressures to lower the risk, according to internal company documents obtained by The Times.
That decision may backfire on Ford, since reduced pressure may have contributed to a rash of tire failures and the recent recall of an estimated 6.5 million Firestone tires, most of them original equipment on Explorers and other SUVs and light trucks.
The suspect tires have been linked to hundreds of reports of tread separations and at least 54 deaths--mostly involving Ford Explorers that rolled over or crashed when their tires failed at highway speeds.
Even if the blame lies squarely with defective tires, Ford could still face liability for marketing a vehicle that, like other SUVs, was prone to roll over if the tires, for any reason, happen to fail.
As it turned out, the Explorer became the most popular SUV ever, selling at least 3.5 million vehicles to date. And while Ford says the rate of rollover fatalities in the Explorer has been 26% less than for comparable SUVs, its decision to recommend lower tire pressures could come back to haunt it.
The Ford documents, which have been produced in lawsuits, show that as the launch date for the Explorer fast approached, company engineers were still struggling to verify that the new model would be less tipsy than Ford’s Bronco II, the rollover-prone SUV that the Explorer was about to replace.
Months before the launch, a prototype of the Explorer had failed badly in rollover tests, lifting two wheels off the ground in five out of 12 steering maneuvers meant to gauge the rollover risk.
According to the documents, a rival Chevy S-10 Blazer had passed easily, keeping all of its wheels on the ground in six test runs out of six. Even worse, the prototype was outperformed on the test by a Bronco II.
The Explorer “must at least be equivalent to the [Bronco II] in these maneuvers to be considered acceptable for production,” a Ford engineer wrote in a 1989 memo.
Determined not to let a February 1990 production date slip, Ford officials spurned some proposals for stability improvements, such as widening the Explorer’s track width, the documents show. The company tweaked the vehicle in other ways, however, to satisfy itself that the Explorer would be at least marginally more stable than the Bronco II.
Among “handling strategies” to improve stability was “tire pressure reduction,” one memo said.
As lawsuits mount over accidents linked to the tire failures, Ford may come to regret its advice to Explorer owners to inflate their tires to 26 pounds per square inch, because underinflated tires get hotter and more stressed. The sidewalls of the tires specify inflation at up to 35 psi, and Firestone has recommended 30 psi.
“The evidence is clear that Ford knew that this vehicle could be redesigned so that you did not have to make the kind of cosmetic, superficial modifications that they were trying to make with the tires,” said Tab Turner, a Little Rock, Ark., who over the years has filed more than 30 lawsuits stemming from Explorer rollover crashes, including some involving blown tires.
Ford’s tire pressure advice, according to Turner, has contributed “to these tires coming apart.”
Ford officials, who initially said the tire pressure advice was designed for a softer ride, have since conceded that stability concerns were also on their minds.
The 26 psi “was chosen to optimize all the performance characteristics of the Explorer--including ride, including handling, including stability,” said Ford spokeswoman Susan Krusel.
And company officials, who say the Explorer’s safety record is better than most SUVs, call tire inflation a red herring.
“Clearly, a severely underinflated tire is going to build up heat, and heat’s the enemy” of tires, acknowledged Ford spokesman Jon Harmon. But he said that “severely underinflated” means less than 20 psi--adding that Goodyear tires fitted on half a million Explorers with the same recommendation of 26 psi have not suffered the peeling of treads experienced with Firestone tires.
But at the very least, the tire inflation issue could drive a wedge between Firestone and Ford, long-time automotive partners who are doing their best to stay on the same page in coping with the furor.
Michael Goldstein, a San Diego County attorney and veteran of tire failure cases, said tire makers’ standard defense in such suits is that consumers tortured the tire by underinflating them. According to Goldstein, that defense may be harder for juries to swallow given the divergent advice from Ford.
However the tire issues play in court, the flap has highlighted the handling limitations of Explorers and other SUVs--as well as the choices facing Ford as it prepared for the launch of the top seller.
Although there is substantial variability between models, SUVs on average have about the same risk of fatal accidents as most passenger cars. In part, this is because occupants of heavier, taller SUVs are more likely to survive a collision with a car than the people in the car. But SUVs are more at risk from single-vehicle crashes--including fatal rollovers, which occur two to three times more often in SUVs than regular passenger cars.
These rollovers typically occur when an SUV swerves to avoid an obstacle, or drifts off the road and veers back suddenly to regain it. The high center of gravity makes SUVs more unforgiving and at risk of flipping over in these sharp steering maneuvers.
That also means they are more prone to severe accidents when a tire fails at highway speeds--as with many of the reported cases involving the Firestone tires. Equip an SUV “with tires that, for one reason or another, are going to experience tread separation [and it’s] a recipe for disaster,” Goldstein said.
Internal Ford documents suggest that company engineers were deeply concerned about vehicle stability during the transition from the Bronco II to the Explorer.
About 760,000 Bronco IIs were sold from model years 1984-90, after which the line was discontinued, though many are still on the road. The compact SUV ranked in the “middle to poor” range in rollover crashes, according to a Ford memo from the late ‘80s.
Through 1998, federal accident statistics showed that Bronco IIs were involved in 1,523 fatal rollover crashes, according to Randy Whitfield, a Maryland-based safety consultant. A court exhibit reviewed by The Times shows that Ford had settled 679 Bronco II rollover claims as of January 1999.
The dubious record was unfolding as Ford prepared the Explorer to replace the Bronco II. The Explorer’s longer wheelbase was expected to result in a more stable vehicle.
But Ford engineers noted in a May 1987 memo that the Explorer prototype actually was worse than the Bronco II in its stability index--a calculation factoring track width and center of gravity height to predict the rollover risk of vehicles. The memo proposed several design changes, including widening the Explorer’s track width.
Other documents discussed research suggesting that Ford’s twin I-beam suspension--used in the Bronco II and destined for use in the Explorer--posed a stability constraint. A 1989 memo discussing the research described the phenomena of “jacking” and “track narrowing” in tight steering maneuvers--with suspension components squeezing together for a split second and causing the vehicle width to narrow slightly and the center of gravity to rise as the engine lifted upward.
Other memos show Ford looking for stability gains through choice of tires and inflation pressures. For marketing reasons, Ford wanted to fit the Explorer with big, macho-looking tires, although that could raise vehicle height.
However, lower tire pressures would help with stability because softer tires are less responsive to the severe steering maneuvers that cause SUVs to tip over. In computer simulations of the prototype’s stability in severe maneuvers, “performance issues occur . . . at 35 psi,” said a Ford memo in the fall of 1988. But “we expect to get a favorable . . . analysis . . . at 26 psi.”
Yet softer tires alone would not do the trick.
In the spring of ’89, Ford ran three vehicles--an Explorer prototype, a Bronco II and a Chevy Blazer--through a series of severe steering maneuvers at its Arizona proving grounds, using different tires and inflation pressures and varying the weight of vehicle loads.
Neither the Blazer, which ran the course six times, nor the Bronco II, which ran it twice, established “a rollover response during any of the . . . maneuvers at speeds up to and including 55 mph,” according to a May 11, 1989, summary of results.
But in five runs out of 12, the Explorer “demonstrated a rollover response, established by observing two wheels off the ground and/or outrigger contact” with the ground, the memo said.
The timing was hardly ideal. The first Explorers were to roll off the production line in just nine months. The rollover risks of the Bronco II were being highlighted in Consumer Reports. And it appeared the Explorer might be no better.
Auto publications had been calling the new model the “new Bronco II.” But Ford had decided to rename it. A June 1989 memo acknowledged that renaming the vehicle might raise suspicions. “A new name for Bronco II likely will be seen by some news media as an attempt by the company to distance itself from the ill-founded rollover publicity,” the memo said.
Meanwhile, Ford engineers were struggling to beat the performance of the Bronco II. A June 1989 memo outlined four proposed design changes to increase the stability of the new vehicle. The memo noted, however, that two of the changes could take up to 40 weeks to accomplish, well past the scheduled production date.
The biggest stability payoff--widening the track width--was among those that would have taken the longest and it was rejected.
But company executives did approve two smaller changes to enhance stability: lowering the vehicle by half an inch and stiffening the front springs, according to a July 1989 memo.
“During the engineering, many modifications were made in order to meet our own requirements for stability,” said Ford’s Krusel. “Those did include lowering the vehicle . . . and increasing” stiffness of the springs.
As for ideas that were rejected, “We look at a number of options and incorporate the ones that make the most sense,” Krusel said.
Even with the design improvements, there still were “fundamental constraints” on stability, including the twin I-Beam suspension, said an undated memo that appears to have been written in 1989.
But according to the memo, the Explorer’s stability index had been hiked above that of the Bronco II. And in what apparently referred to its potential popularity with families, the memo said the Explorer’s “less aggressive driver profile” should also mean a “reduction in all accident statistics.”
Beginning with the 1995 models, Ford replaced the Explorer’s twin I-beams with the SLA, or short-long arm suspension. Officials said the move was not made for stability reasons but to make room for other design changes.
The company has boasted that the 2002 Explorers, due out early next year, will incorporate many safety and stability improvements. Among them: a longer wheelbase and wider track width.
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