Ford Explorer Problems at Issue
Ford Explorer SUV, including the Ford Explorer Sport & Sport Trac can be very hard to handle and control in emergency braking, quick steering and avoidance maneuvers resulting in rollovers. Often drivers involved in rollovers of SUVs and especially Ford Explorers are cited by investigating police officers for over-steering, over-correcting and for failure to control speed. In the fall of 1990, Ford Motor Company introduced the Ford Explorer. It was the replacement for the popular, but rollover prone SUV called the Bronco II.
The 1991 Ford Explorer was introduced as a two-door or four-door, with either two or four-wheel drive transmission. Unlike some competitors, the two-door was built on a shorter (102.1-inch) wheelbase than the four-door, which had a 111.9-inch wheelbase. Ford's apparently thought that the motoring public wanted a sportier, more maneuverable vehicle would go with the two-door where as those who needed more passenger room would opt for the quattroporte. Curb weights ranged for around 3,700 pounds for a 2WD two-door to about 4,000 pounds for a 4WD four-door. In 1992 Ford changes the 3:55:1 tear axle to a 3:27:1 to improve gas mileage and lower rpm's at highway speeds. In 1993 anti-lock brakes and stress-reducing binders were made standard on all Explorers. In 1995 a huge facelift occurred in the appearance and style along with the inclusion of driver and front passenger airbags in the 1995 Ford Explorer, then with improved airbags in 1998 along with optional side impact airbags. In 2002, an optional third seat made possible by a 2-inch stretch in wheelbase, a 2.5-inch-wider track and a new independent rear suspension that lowers the rear floor 7 inches. This lowering also improved the center of gravity of the 2002 Ford Explorer.
Although SUVs are designed to be driven off the road, very few have roll-bars or adequate rollover- roof crush protection. And to make matters worse, few meet the National Highway Traffic and Safety Administration roof safety standards for automobiles [as weak as those standards are].
In an internal Ford memo in 1991, it was estimated that the increased costs of the roof redesign at $1,267 per vehicle, despite cost-reduction programs. According to another document, thinner metal panels were used to construct the Ford Explorer roof. Many experts say most vehicle roofs are extremely weak, thanks in part to a federal roof crush standard that has not been changed for three decades, and was widely regarded as ineffective at the time it was adopted. Safety advocates say the issue is important because a major cause of deaths and paralyzing injuries in rollover crashes is the roof collapsing onto occupants. However, the Ford memo did not make clear whether the plan to thin the roof of the '95 Explorer would weaken it. The document signaled an intent to reduce the "gage," or thickness, of the roof panels "and go to baked hardenable"--a reference to using heat to temper the steel. The chief hazard occurs when taking emergency action after steering in one direction and then being forced to rapidly correct in the opposite direction, such as a typical avoidance maneuver with a road hazard, a deer, a dog or even a child in the roadway. The result often times is a roll over. Rollover occurs because of the absence of a lower center of gravity and a wider track width, which allows most automobiles to skid, spin and recover. But when taking a common evasive maneuver that car driver’s safety complete every day, rapidly corrective action causes SUVs to trip and roll.
Another rollover situation is created when there is a sudden tire failure; either from a road hazard type blowout or from a tire treads separation. This sudden loss of control can cause the back end of the SUV, van or light truck to swing out or "fishtail", resulting in the vehicle skidding out and sliding sideways in the direction of travel. When this occurs, the vehicle can often trip and go airborne, starting the rollover. Rollovers are the most common cause of roof crush. Over 10,000 people are fatally injured each year in rollover crashes. The causal relationship between rollovers and harm to occupants from roof crush has been recognized as early as the 1930's. Nevertheless, the automotive industry denies the relationship between roof crush and occupant injuries in rollovers. When the Ford Explorer was introduced, Ford was concerned enough about its stability that it advised owners to maintain a relatively low tire pressure of 26 pounds per square inch, because softer tires help an out-of-control vehicle to slide rather than tip over. Yet the redesign in the '95 model year made the Explorer's center of gravity slightly higher and the stability index--a rough measure of rollover propensity--slightly worse, records show. With the new suspension system Ford installed in 1995 and later model Explorers, the auto maker could have lowered the center of gravity of the top-heavy vehicles by lowering the engine height, according to memos by Ford engineers. But the company decided to retain the original engine position, at least partly to hold down redesign costs and preserve profit margins of nearly 40% on the popular Explorer, the documents show. A Ford spokesman acknowledged a small rise in the Explorer's center of gravity with the '95 redesign, but said the difference is inconsequential.
The main part of the vehicle's structural support system, the roof creates a "non-encroachment zone" or "survival space" that should protect occupants in a crash. If a roof crushes inward substantially in an accident, occupants may suffer disabling head and neck injuries or even death. Most passenger vehicles and many SUVs do not have enough headroom to allow for more than three to four inches of crush without significantly increasing the risk of serious injury or death. NHTSA's FMVSS 216, sets the minimum strength requirements for a vehicle's roof crush resistance, but does not require manufacturers to conduct dynamic rollover tests on roofs.
In a rollover, the roof can crush into the occupant space in several different ways. Matchboxing, pillar collapse and header collapse are the most common ways that this occurs. In most cases, a stronger roof support system would have prevented most of the serious neck, head and spinal injuries. To the untrained observer, roof pillars of most vehicles appear solid and sturdy, especially strong enough to withstand a roof crush in a rollover. The surprises come through when one looks at a cross-section of the pillar. Most are nothing more than folded/molded corrugated sheet metal, being hollow inside. Therefore, when impact occurs the metal folds over into the empty inner space allowing more folding or crushing to continue. Tests show that if the inner hollow part of the roof pillars are either filled with a high density foam or honey combed structure, then roof crush is at a minimal, thus saving lives!!
When the roof collapses or invades the safety zone, then the neck fractures often occur. These result from shear and flexion forces unto the neck and spinal cord of the occupants. Roof crush injuries are caused by the energy of the vehicle in a roll creating compressive forces pushing down on the top of skull when the head is in an upright position. The compression causes a bursting fracture in the C5 to C7 of the cervical spine. This bursting fracture causes a loss of intravertebral space both anterior and posterior.
In other rollovers, the roof intruding is not the cause of injury. Another type of serious neck and head injury occurs when the occupant "dives" into the roof, resulting in the head flexing forward before receiving an impact to the top of the head. This so-called dive can often result from too much slack introduced into the seat belt system and from unrestrained occupants. This causes the bone in cervical vertebrae to fracture, (NOT A BURST). The posterior corner of the vertebrae then impinges directly against the spinal cord resulting in loss of anterior vertebrae body height. Diving type injuries can happen to belted occupants, who for many reasons become unbelted or unrestrained during a rollover.