Trucks, Jeeps

Developing the 1998-2003 Dodge Durango chassis:
suspension, towing, frame

Click here for the main Durango page

Details follow the overviews.

Chassis NVH Control

Power Train Mounts

Front and rear power train mounts are the same as used on Dakota. Large diameter - 3.5 inch (90 mm) - spool-type elastomeric front mounts are refined from mounts of similar design used on Ram pickups. Each mount supports the engine at the top of an inverted rubber "V". The mounts are tuned to produce a desired natural frequency by adjusting the size and shape of the legs of the "V". Tuning is selected to provide a natural frequency that will damp out engine movement caused by front suspension inputs and control V-6 idle shake. Damping suspension-induced power train motion reduces harshness. A unique damping patch added to the mount quickly dampens bouncing motion of the power train and allows the effective use of tuning to damp out suspension inputs without causing undesirable aftershake. To isolate the cab from high-frequency power train noise and vibration, the mounts use a large volume of very soft rubber. The large volume of rubber minimizes rubber stress for exceptional durability. Shear-style transmission mounts help maximize isolation properties.

All power train mounts are tuned as a system for each engine-transmission-drive combination through subtle variation in rubber. Local stiffening of the power train mount brackets on both engine and frame significantly reduces noise transmitted from power train to interior. Local stiffening makes the rubber a more effective isolator.

Antilock Brake System Hydraulic Unit

The antilock brake system is double-isolated to prevent solenoid and check valve noise, which occurs during antilock action, from being transmitted to the cab. There are rubber isolators at the attachments of the hydraulic unit to its mounting bracket and from the bracket to the body structure.

Dodge Dakota ride and handling

"For Dakota, we set out to make a truck that worked hard, but offered a much tighter feel than pickup customers had grown accustomed to,"said Dennis Moothart, Executive Engineer for Truck Chassis Engineering."With Durango, our goal was the same: Surprise the typical compactSUV owner in terms of ride and handling."

As in Dakota, the mission for Durango was to focus on the basics. This meant making a chassis that was tunable.

Frame Design: Maximum Stiffness, Minimum Weight

Starting with frame design, Durango engineers stiffened it to handle the greater - and higher - mass of an SUV. By making it more than three times stiffer than the Dakota 4x4, a framework was established to tune steering,suspension and body mounting. It's fully boxed almost all the way to the rear, and utilizes two hydroformed crossmembers welded to the side rails for maximum torsional stiffness.

Maximized stiffness was not done at the compromise of weight, as Durango's frame weighs only slightly more than a Dakota at the same wheelbase. This was accomplished by doing extensive computer modeling of the frame and using newly-developed gage (thickness) optimization programs. The Durango frame is splayed outboard at the rear and the section height provides increased room for the interior package. The stiffness was returned to the frame by boxing the rails.

"Stiffness couldn't come at the sacrifice of handling," Moothartsaid. "Our target was the Dakota feel in an SUV frame, which meant keeping the weight gain to a minimum. We consider the Durango's diet plan a success."

Chassis design played a role in accommodating the additional passenger and cargo space. In addition, room was created for a larger fuel tank (25gallons), a low-restriction exhaust system and a full-size spare tire behind the rear axle.

Steering and Suspension: The 'Sport' in Sport Utility

As in Dakota, truly optimized steering and suspension geometry, a large wheel-and-tire package and appropriately-sized shocks and bushings provided the framework for Durango's agility and comfort both on- and off-road.

Variable-ratio steering with a quicker overall gear was added to Durango to give it a more nimble feel and greater maneuverability in parking and turning. The ride height was lowered one inch for easier entry and exit and helped offset the center of gravity height increase, thereby improving handling.

"An SUV naturally gives you a taller platform, but we didn't want that to take away from the handling," Moothart said. "By lowering the suspension just one inch, we were able to go a long way toward compensating for the additional body work and interior mass.

Brakes: Built to Tow

Durango's brakes were enlarged to handle the increased weight versus Dakota, helping to handle its best-in-class 7,300 lb. towing capacity. Standard brakes are 11.3" x 0.9" vented disc front and 11.0" x 2.25"drum rear, with ABS. An optional four-wheel ABS package is available.

Structural Stiffness and Strength

Durango's structural stiffness and strength are derived from the combinationof body, frame and mounts. These were designed and engineered as a systemto meet vehicle objectives for ride, handling, comfort and quietness. Designof the Durango structure began with extensive benchmarking of competitivevehicles through both testing and subjective evaluation. Vehicle Development evaluated the vehicles at the Chelsea Proving Grounds for ride, handling, quietness, vehicle shake and seat shake. These evaluations were correlatedwith each vehicle's measured structural strength and stiffness to determine the structural requirements for Durango. Body mounts were instrumented duringthe drive evaluations to measure load inputs from the frame - to determinewhich vehicle had the optimal load distribution. Key structural performancetests of overall bending and torsional stiffness for body, frame and totalvehicle were supplemented by detail tests of isolator stiffness, seat mountingstiffness, localized stiffness at mounting points, and even body panel stiffnessas it relates to dent or "oil canning" resistance. Frames andbodies were examined independently and in assembly to determine the bestexisting combination. Comparisons were also made between these vehiclesand the pickup trucks from which they are derived.

Shake was evaluated by Modal Testing in which the vehicle is subjectedto white noise (random frequency) vibrations through the suspension systemand the response is measured at places that occupants touch or see: seats,steering column, front body panels, etc.

"Loose" panel stiffness - deflection of hood, liftgate anddoors when open - was also measured.

The bodies were also cut up to determine how the stiffness was achieved.Cross sectional area, thickness and material strength of all structuralmembers were measured. In addition, the static stiffness of each weld jointwas measured.

Based on the benchmark test results, a set of structural performanceobjectives was established for Durango that would produce a best-in-classvehicle structure by matching or exceeding the benchmark in every structuralcategory. An expanded team of structural analysts assembled computerizedstructural models of the Durango body and frame and performed numerous FEA(Finite Element Analysis) iterations, refining the structural models untilthey met the objectives. The modeling and structural design process proceededinteractively, making changes on a day-to-day basis in unison with frame,body and interior functional design, addressing occupant packaging requirements,and in consideration of vehicle functional and quietness requirements.

Nonlinear FEA, being used on Durango for the first time in some cases,assured ample strength to meet safety standard requirements for frontalimpact, side impact and seat belt loading. Nonlinear FEA was also used toverify door slam durability and door sag resistance.

While the benchmark studies showed that frame stiffness varied amongcompetitive makes, all were noted to be much stiffer than their pickup forebears.Durango frame torsional stiffness is best among competitive brands - approximately1,000 ft.-lb. per degree. Appropriate stiffness permits fine tuning of thetires, springs, shock absorbers and body mounts to provide a quieter, morecomfortable ride and an overall solid feeling.

The overall increase in frame stiffness relative to Dakota is in therear section - the front sections are identical. Stiffness and strengthare typically achieved at the expense of weight. Metal thickness in theDurango frame rails and crossmembers was optimized for required stiffnesswith minimum weight through extensive use of FEA. An elaborate finite-elementcomputer model of the complete frame - the most extensive ever done on aDodge truck frame - was used to maximize efficiency of the rails and crossmembers.

Major emphasis was placed on achieving a rigid body - stiffer than anyprevious Chrysler body-on-frame vehicle - to give the customer a vehiclewith a truly solid feeling. The result is an overall body torsional stiffnessover 5,000 lb.-ft./degree. Using the benchmark data to establish objectives,a body structure with an optimum strength-to-weight ratio was achieved throughiterative FEA analysis; one having appropriate thickness of outer panels,laser-welded inner panels, minimum area of structural members, and carefulattention to welding joint designs.

Special design features to assure high stiffness included:

  • Halo structures at the center pillar (B-pillar) and liftgate opening. Through iterative FEA analysis, these structures provide uniform stiffness all around the hoop - pillars, roof bow, underbody crossmember and welds in the center; pillars, header, sill and welds at the liftgate opening. Key to achieving this uniform stiffness was the addition of gussets and subtle rearrangement of panels and welds so that loads (and stresses) are distributed, making all components contribute to the stiffness
  • Rigid doors that feature laser-welded inner panels and FEA-designed structure provided customer perceived strength - doors that are less likely to sag under load over time
  • Full-depth crossmembers under the floor pan at five locations - deeper than those on any prior Chrysler full-frame vehicle. Unique sill to crossmember welding joints distributed the loads to enhance torsional stiffness
  • Large sill sections contribute to high beam stiffness

For maximum isolation between body and frame, body mounting points coincidewith major structural members - the front of the engine compartment, eachbody pillar and the third seat. A crossmember located at each of these pointshelps keep the body quiet and free from harshness by minimizing deflectionwhere the mounting loads are applied.

Chassis

To accommodate a large fuel tank - 25 gallons (95 L), the frame railsare splayed. This has resulted in mounting the spring hangers under theframe rails and in the use of underslung rear springs, a common practiceamong 4WD sport-utility vehicles.

Widely spaced rails also provide accommodation for a matching, full-sizespare tire with all available tires, whereas some competitive vehicles mustresort to a smaller spare with their large optional tires.

Though lower than Dakota, Durango has up to 1.5 inches (38 mm) more running ground clearance than its domestic competitors.

Chassis

Frame Construction

Basic frame construction retains the three-part side rail concept pioneered by Ram pickup and used in the new Dakota. The front third is identical with the 4WD Dakota, but the remainder is unique.

The front section, which ends under the front seat, has robust, nested C-section or boxed two-piece rails. Other features of the front section developed for Dakota include stiff torsion bar and transmission crossmembers. The stabilizer bar is mounted to an existing frame crossmember to reduce deflection. The front rails are positioned to provide tire clearance for a tight turning circle.

Side rails aft of the front section are widely spaced to accommodate a large, low-profile fuel tank ahead of the rear axle. Widely spaced rails also make room for the spare tire under the cargo floor, increasing usable interior volume. Center and rear section rails and crossmembers have a lower profile than on Dakota to provide room for second and third-seat passengers while maintaining rear suspension travel. Center section rails are fully boxed and welded for stiffness. Rear rails are partially boxed; the boxed section extending farther rearward than on any competitive frame.

Center and rear section crossmembers are more numerous and robust than those of the pickup frame for added stiffness. For efficiency, the rear fuel tank and shock absorber crossmembers are hydroformed. Hydroforming reduces weight and complexity by using water under high pressure to press a tubular member into conformity with an external die, making add-on brackets unnecessary. In this way, the number of parts in the shock absorber crossmember was reduced from five to three. Side rails and crossmember joints are all welded. Stiff mounting brackets for suspension and body assure that the overall frame stiffness is used effectively. A strong optional transfer case skid plate results from heavy gauge material and a rigid mounting arrangement.

Durability

Like Dakota, Durango frame durability is expected to be substantially better than prior-generation trucks, resulting in a structure that will stay tight throughout the life of the vehicle. The frame is made primarily of 35,000 psi yield strength steel with selected brackets of 50,000 psi yield strength HSLA (high strength, low alloy) steel for weight reduction.

Corrosion Protection

The frame is electro-coat painted to significantly increase corrosion protection and improve both short- and long-term appearance. This immersion paint process assures complete coverage and a uniform coating. The finish is impervious to vehicle fluids and has a durable, low-gloss finish that is smooth and hard to the touch. This gives Durango a significant advantage over domestic competitors that still use the traditional wax-dip coating, which drips in hot weather, rubs off, is less pleasing in appearance and offers less corrosion protection.

Dimensional Control

As the mounting point for the bumpers, body, suspension, steering and power train, the frame is a major contributor to dimensional control throughout the truck. For highest accuracy, all frame dimensions are measured from a single set of principal locating points (PLP). The processes used to achieve the desired level of accuracy were refined through multiple iterations of Variation Simulation Analysis (VSA). VSA uses production process parameters to predict the degree of accuracy produced by a set of processes. In the approved process, the frame is manufactured in three stages:

1. The basic frame is welded using the PLP
2. All mounting brackets are positioned relative to the PLP and welded in a single fixture
3. All critical suspension, steering and body mounting holes are pierced in the brackets relative to the PLP simultaneously in another fixture

Body mounting brackets are welded to the webs of the frame after the rails and crossmembers are welded together to permit the fixture to control vertical mounting locations. Lateral and longitudinal mounting locations are controlled by the piercing fixture. Steering toe control for consistent handling is a major benefit of improved dimensional control since the steering gear to lower control arm relationship, which governs this condition, is established by the frame mounting points for these components.

Trailer Hitch Platform

A frame-mounted Class IV trailer hitch platform is available as a factory option on Durango. It provides properly equipped Durango models with towing capacity up to 7,300 pounds (3,311 kg). The platform accepts standard, removable, load-equalizing draw bar units. For an uncluttered appearance, the hitch platform lateral tube is concealed behind the rear fascia. Only the draw bar "box" and electrical outlet are visible.

Suspension Systems

Front Suspension System

The torsion-bar independent front suspension is essentially the same as that used on Dakota. Changes include a 1-inch (25-mm) lower ride height to provide easier passenger entry and exit. Suspension calibration compensates for the reduced jounce travel to maintain ride quality. The effect of the change is less noticeable than in a pickup truck because weight varies less between loaded and unloaded conditions. The front suspension system provides outstanding ride, cornering and steering performance, accommodates 31 x 10.5-inch R15 tires on 15 x 8-inch wheels while allowing a tight turning diameter and provides essential 4WD durability.

Like Dakota, suspension geometry contributes to low camber variation from the nominal setting that is balanced between jounce and rebound conditions. The steering system center link is relocated slightly relative to the 1997 Dakota to balance toe change during jounce and rebound about the curb load position. The effects of these features is to minimize tire wear by keeping the tires upright and pointed straight ahead as much as possible.

Front stabilizer bar stiffness is increased 93 percent from that of Dakota to maintain crisp handling characteristics. To reduce turning circle, the stabilizer bar is mounted forward of the lower control arms. This location is also well clear of the ground to aid all-terrain capability. Stabilizer bar connection to the suspension and bushing material are the same as on Dakota.

Rear Suspension System

Though conventional in construction, using leaf springs and a solid axle, Durango's rear suspension uses S-shaped main leafs pioneered by Chrysler to provide desired handling characteristics. The unique shape contributes to overall handling precision that is unavailable without this feature. A tight toe specification for the rear axle housing contributes to handling precision by assuring that rear wheels maintain a toed-in attitude. Splayed frame rails to accommodate a larger fuel tank necessitated the following rear suspension variations relative to Dakota:

  • Front spring hangers mount beneath the rails
  • Front spring eyes are turned down
  • Compression rear shackles are used
  • Springs are underslung relative to the axle

Underslung springs contribute to smooth operation by reducing axle "power hop," relative to springs mounted atop the axle. As in front, ride height is reduced 1 inch (25-mm) to enhance passenger entry and exit.

Single-stage springs provide consistent ride quality. Smaller variation between loaded and unloaded conditions, that occur with pickup trucks, make two-stage springs unnecessary and avoids the harshness that occurs when loading or sharp bumps bring the secondary leaves of two-stage springs into action. A high basic rate also keeps the body attitude more consistent from empty to loaded condition than do two-stage springs.

A rear stabilizer bar is standard. Larger than that used on Dakota, it helps reduce lean of the taller, heavier Durango body and contributes to handling precision. The bar pivots on the axle housing and is connected to the frame through low-friction links. To enhance stability, rear shackles are 0.5-inch (13-mm) wider at the frame than at the spring and include washers that restrain the rubber bushings. The combination reduces lateral deflection of the springs without affecting ride or increasing harshness. Shock absorbers mount behind the axle to provide entry room for third-seat passengers, but are "sea legged" to help reduce vehicle sway and control lateral shake.

For low harshness, Durango's front eye bushings are the same size as those on Dakota: 1.5 inches (38 mm) in diameter. For better appearance, some suspension fasteners have a black anti-corrosion treatment.

Shared Suspension Components

Micro-cellular urethane jounce bumper, used front and rear on Durango, contribute to high quality ride characteristics by providing a rising rate that reduces harshness and the impact of "bottoming out." Urethane has the added benefits of a nearly constant rate regardless of temperature to help maintain ride quality in all seasons, and greater durability than conventional rubber bumper material.

Durango shock absorbers are the same in design and construction as those on Dakota, but unique in calibration. They use a combination of deflected disc and helical spring valves for maximum flexibility in damper tuning to control ride motions.

Deflection characteristics of the valves permit oil passage area to vary relative to shock absorber velocity. Generally, the faster the motion of the suspension in traversing a bump, the higher the force that the shock absorber experiences. To compensate, the passage area in Durango's shock absorbers increases under load, limiting the damping force. When traversing sharp bumps, which produces high shock absorber velocities, the limited damping force reduces harshness. Conversely, low shock absorber velocities associated with road undulations or cornering gives firm control for stability and driver confidence. Deflected disc valves also have low hysteresis - a temporary buildup of force before movement takes place or when it changes direction - which helps to minimize harshness, and provides smooth transitions between jounce and rebound. Final shock absorber valve configuration is the result of painstaking comparison testing among numerous possible combinations. Oversized shock absorber pistons, 1.38 inch (35 mm) in diameter, for durability and low-speed ride control. All Durango shock absorbers have conventional twin tube construction and a low-pressure gas charge in the reservoir to prevent cavitation (formation of air pockets that can adversely affect ride quality) during rough road operation.

Larger upper shock mounting grommets, as used on Dakota, also increase durability.

Compression-type lower ball joints are shared with Dakota. A compression ball joint is smaller in diameter than a tension joint of equal strength because the compression side of the joint, which has a larger area than the tension side, is used to support the vehicle's weight and jounce loads. A hard, durable plastic ball socket liner on the upper ball joint and a low-friction washer in the lower ball joint contribute to responsive steering by reducing turning loads. Similar reductions in ride friction are compensated by shock absorber tuning. Upper ball joints are permanently lubricated and maintenance-free. Improved sealing assures durability equal to or greater than that provided by ball joints that require periodic lubrication.

Rubber stabilizer bar pivot bushings include low-friction liners that adjust to suspension height without affecting ride but resist wear for long-term quietness and durability.

Suspension System Corrosion Protection

For high quality appearance and corrosion protection, control arms, steering knuckles, the stabilizer bar and its mounts, and the torsion bars are electro-coat painted. Rear shackles and spring clip plates are also painted using an electrocoat process. Rear springs receive a proprietary, two-part treatment consisting of a corrosion-resistant zinc-rich primer followed by an appearance top coat. Springs are also painted.

Most threaded fasteners for the front and rear suspension systems are finished with a proprietary coating that has an appealing bright appearance and is five times more resistant to corrosion than fastener finishes used previously. Some rear suspension fasteners are treated with a black anti-corrosion coating of equal protective capability to make them visually less obtrusive.

Steering System

The steering system provides fast response with excellent road feel. A slight reduction in steering angle compared to Dakota results from the change to larger front brakes. Durango still maintains a competitive turning circle of 38.9 feet that is surpassed only by sport-utility vehicles with shorter wheelbases.

The overall on-center ratio of the power recirculating-ball gear is 15.43:1. Vehicle response is proportional to steering inputs for a feeling of direct connection between driver and road that helps make the vehicle fun to drive. The valve and torsion bar on this gear are the same as on Dakota.

Precision feel is gained through low internal friction. Rigid low-friction linkage, which also contributes to precision and responsiveness, is likewise shared with Dakota. In-line spherical joints connect the center link to the tie rods, minimizing deflection under load. Low-friction plastic liners in these joints help minimize friction. The tie-rods thread directly into the tie-rod ends and are held in adjustment by jam nuts. This makes toe adjustment more precise and easier than with a clamped-sleeve arrangement. A precise conical joint transfers steering motion from the Pitman arm of the steering gear to the center link. A spherical joint, which compensates for minor angular variations in the linkage, is mounted on the idler arm where it does not affect precision. Also contributing to precision feel and excellent steering returnability, are low scrub-radius suspension geometry and low-friction, compression-type lower ball joints shared with Dakota.

Tires and Wheels

Durango offers larger standard tires - size P235/75R15 - than most competitive vehicles. Tires and wheels were developed simultaneously with the steering and suspension systems to provide the desired performance characteristics. Rim width is particularly significant with regard to ride and handling, and Durango uses wide ones - 7 or 8 inches - for better performance. Tires selected for the vehicle carry the same proprietary names, appearance and basic tread patterns as those on Dakota, but both have been fine tuned to Durango's requirements. Tires with these same names are sold to other manufacturers and in the aftermarket, but they are not built to the same specifications as the Durango tires. Production specifications for each tire configuration represent a balance of performance requirements among each of the following attributes:

  • tread wear
  • tread noise
  • rolling resistance
  • wet handling
  • dry traction
  • dry handling
  • wet traction
  • ride
  • snow traction

Tires

Goodyear Wrangler RT/S steel-belted radial tires, size P235/75R15XL, are standard. Using these tires instead of light truck tires allows more latitude for tuning of shock absorbers, structure and mounts to achieve passenger car-like ride and handling. Larger tires, relative to competition, improves ride quality because of their taller cross section and increases tread life because of their greater circumference. These tires have a tread design that makes them proficient in all-terrain operation yet is quiet on pavement, making a choice between all-season and all-terrain tires unnecessary. An outline white-letter sidewall appearance on tires of this same size and construction is included with SLT and SLT+ equipment.

Wrangler RT/S tires size 31 x 10.5-inch, are optional with SLT and SLT+ equipment. These tires offer the handling and ride benefits of larger tires along with the all-terrain benefits of their smaller counterparts described above. The 8-inch rim width used with these tires maximizes the tire footprint.

Wheels

New lightweight forged aluminum wheels, used here for the first time on a Dodge truck, are standard with SLT and SLT+ equipment. They offer a stylish polished appearance and are 17 to 21 percent lighter than cast wheels of the same size. Lighter weight is the result of the forging process and use of a high-strength aluminum alloy. An acrylic Clear Coat protects the bright finish.

Spare Tire, Jack and Tools

A full-size spare tire and wheel assembly is stowed horizontally under the rear floor pan. Unlike some competitive vehicles, there is also room for the optional 31 x 10.5-inch tire and wheel assembly. A winch operated by the tire lug wrench raises and lowers the tire. The tire is secured against theft because the winch is accessible only through an opening in the storage tray at the rear of the cargo area. The opening is covered by a snap-in plug. The compact scissors-type jack and tire changing tools are clamped to the floor in this compartment, providing best-in-class jack and tool stowage. A jacking instruction label is attached to the underside of the cover.

See also Floor Storage Modules under Interior Trim in the Body Interior section.

Brake Systems

Durango's braking system provides car-like response that complements its ride and handling characteristics. Directional control during hard braking is enhanced by front suspension geometry with reduced scrub radius which is shared with Dakota.

New sliding caliper front disc brakes and duo-servo drum rear brakes are standard on all models. At 2.75-inch (70-mm) diameter, Durango's single-piston front brake calipers are larger than those on Dakota to assure ample braking with capacity to spare on this heavier vehicle with greater trailer towing capacity. The larger calipers are accompanied by longer shoes. Rotors remain the same as on Dakota - 11.3 x 0.9 inches (287 x 23 mm). Due to a heavier body with a rearward weight bias relative to Dakota, Durango has 11 x 2.25-inch rear drum brakes. Durango brakes are comparable in size to those provided by competitive vehicles.

Pads for the front brakes are longer than those on Dakota and also more voluminous and effectively thicker because they are bonded rather than riveted to the shoe plates. Both of these factors are expected to result in extended lining life. Furthermore the bonding process is expected to result in quieter operation. Lower noise is the result of a softer underlayer between shoe plate and lining than is possible with riveted shoes and because the insulator between shoe plate and piston is adhesive- bonded rather than riveted in place.

An integrated booster and master cylinder requires minimal pedal travel to actuate the brakes, enhancing driver confidence. To maintain comfortable pedal effort and effectively operate the larger brakes, all Durango models have a more powerful 8.07-inch (205-mm) tandem-diaphragm booster and a larger, 1.06-inch (27-mm) master cylinder bore than Dakota.

The brake system includes the following additional features:

  • All systems are self-adjusting
  • Lining materials contain no asbestos
  • Front disc brake calipers, rotor center sections and rear brake drums have a black anti-corrosion coating for durability and neat appearance
  • Brake lines receive an aluminum-rich coating for long life

Shields help protect the front discs from dust, dirt and road splash to reduce lining wear during all-terrain driving.

Four-Wheel Antilock Brakes

A new generation antilock brake system is optional on Durango. System components are smaller, lighter and less complex that those used on Dakota in 1997. The only perceptible difference in performance relative to Dakota is an increase in pedal feedback similar to that provided by passenger car systems. As on Dakota, the system provides powered ABS action to the rear brakes that enhances stopping distance and control for the driver relative to systems that do not have this feature. Functionally, powered operation means that if hydraulic pressure is released to prevent lockup, the hydraulic unit will pump the fluid back into the rear brake system to maintain pedal height.

Low scrub radius front suspension steering geometry shared with Dakota also contributes to improved antilock performance by allowing the system to provide aggressive initial application while maintaining directional control and steering capability.

Front wheel sensors integral with the hub bearings are the same as on Dakota. They are simpler and more reliable than external sensors. The single, rear-axle speed sensor, which is shared by four-wheel and rear-wheel antilock (RWAL) systems, continues to use the ring gear as its trigger.

As on Dakota, the antilock brake system is operated by an electronic control module that is integrated with the hydraulic unit. This integration simplifies the wiring and enhances system reliability by providing internal electrical connections that eliminate 15 external electrical circuits required without this feature. This integration also reduces the weight of the system by approximately 2.5 pounds (1.1 kg) relative to prior practice. ABS system diagnostic signals are communicated to the instrument cluster warning indicator and the central data link connector over the multiplex data network.

Rear-Wheel Antilock Brakes

Durango uses an upgraded electronic controller for its standard rear-wheel antilock brake system, which is shared with other 1998 Dodge trucks. The new controller mounts under the hood and is both electromagnetically compatible with other electronic systems and protected against the heat and contamination of the underhood environment. Unlike controllers on prior vehicles, RWAL diagnostic codes are retained in memory. Retrieval of the codes is also easier because they are communicated over the multiplex data network to the central data link connector for output to a DRB III scan tool. A malfunction indication will also be transmitted to the instrument cluster warning indicator over the multiplex data network. A single speed sensor on the differential housing provides the input signal to control the rear drum brakes as on prior systems.

Parking Brake

Durango uses the same pedal-operated parking brake mechanism as Dakota for smooth, quiet operation. Applying the brake produces none of the characteristic ratchet sound of prior systems. Instead of a ratchet, the new mechanism uses a square-edged spring that wraps around a drum operated by the brake pedal to keep the brake engaged. When the brake is applied, the drum slides smoothly inside the spring. When foot pressure on the pedal is released, the spring grips the drum and prevents it from returning to its released position. The release lever is integrated with the lower edge of the instrument panel just above the pedal. Release operation is also smooth and quiet with low effort. The mechanism releases gradually, by pressing against the end of the square-edged spring to reduce its grip on the drum, allowing the pedal to rotate back to its released position smoothly.

Fuel, Exhaust and Cooling Systems

A 25-gallon (95-liter), three-layer, co-extruded plastic fuel tank is standard. The center layer of the tank is a fuel permeation barrier to prevent evaporation through the tank's surface. The tank mounts ahead of the rear axle and inboard of the left frame rail, the same location as Dakota.

A door in the left quarter panel conceals the fuel filler cap. The door pivots on a spring loaded hinge that holds the door open for refueling. The cap is tethered to the door hinge. As on Dakota, a one-piece filler tube terminates in a plastic filler neck housing attached to the quarter panel. Fuel line life is enhanced by adding a nylon coating for corrosion protection.

Exhaust System

Durango has a unique exhaust system to ensure quietness for rear-seat passengers. The large muffler is not only quieter than that on Dakota, but has lower back pressure for enhanced engine performance. Large, full-diameter pipes also contribute to low back pressure. A cylindrical, metal-substrate catalytic converter was made necessary by the larger muffler. This construction is space efficient, resulting in a smaller housing than with conventional clam-shell construction. Metal walls of the honeycomb substrate are thinner than those of the customary ceramic substrate and the cylindrical shape helps distribute exhaust more uniformly across the face of the substrate than the customary oval shape. The tail pipe runs straight to the rear of the vehicle and terminates beneath a clearance notch in the fascia. A hanger at the rear maintains alignment with the fascia, while other hangers are located at vibration nodes to minimize noise transmission and increase system durability. Node locations were determined by vibration mapping. The muffler, catalytic converter housing and all pipes remain stainless steel.

Cooling System

Durango radiator construction is the same as on Dakota. Crossflow aluminum radiators with plastic end tanks provide ample cooling capacity for all engines. Mechanically attached plastic end tanks handle thermal expansion cycles better than the conventional soldered copper-brass construction for longer life. Aluminum radiators weigh less than copper-brass radiators of comparable cooling capacity. With appropriate coolant formulation, aluminum has double the corrosion resistance of copper-brass. Crossflow construction is used because its low, wide configuration consistent with Durango's low hood line.

A state-of-the art mounting system is shared with Dakota. It ensures long radiator life. Rubber mounts isolate the radiator from engine and chassis vibrations.

Lowest fan noise consistent with cooling requirements is a Durango objective. Fan size is tailored to each engine. This not only minimizes noise, it also reduces the fan's power requirement to increase fuel economy. Fan drives are fine tuned to reduce fan speed for lower noise where appropriate. Working against lower fan noise are higher GVWR and GCWR requirements, compared to Dakota, resulting in the use of nine-blade fans and more aggressive fan drives. While running faster most of the time and moving more air, the nine-blade fan produces a unique and more pleasant sound that clearly distinguishes it from engine flare.

Like Dakota, all Durango engines use a more robust thermostat than in the past for longer, more reliable life. Subtle design and manufacturing process changes make the thermostat more durable and also provide closer control of temperatures than the prior design.

The coolant recovery reservoir is mounted forward of the radiator closure panel as it is on Dakota, with its neck extending into the engine compartment through an opening in the closure panel for easy access. The bottle is molded in black plastic to match the black paint on the front of the closure panel for a consistent appearance, but the cap is yellow with black nomenclature for easy identification.

The maximum cooling package, which is required for towing heavy trailers, includes a higher capacity fan drive, and an auxiliary transmission cooler mounted ahead of the radiator. This package helps give Durango its best-in-class maximum GCWR (gross combined weight rating) of 12,200 pounds.

Click here for the main Durango page

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