Development of the Body Shell, Suspension, and Steering of the Chrysler LH Series (Dodge Intrepid, Chrysler Concorde, Eagle Vision)
Suspension, ride, and handling features - Intrepid, Concorde, Vision
Although the developmental code name for Chrysler's newest passenger cars -- LH -- was meant to be all encompassing, it easily could reference the "leveraged handling" characteristics of the 1993 Dodge Intrepid, Chrysler Concorde and Eagle Vision.
This trio may well represent the most balanced handling four-door sedans America had ever produced for the mid-size, medium-price market segment -- better than any Japanese competitor in this range and on a par with the best Europe has to offer at any level. That’s not just an assertion: "Steering feel and handling response may be open to some interpretation, but some parameters such as roll angle and maximum lateral acceleration can be measured," said Mark Pedersen, senior vehicle dynamics engineer on Chrysler's Large Car Platform Team.
The design objective for the LH's four-wheel, fully-independent suspension system -- Chrysler's first [aside from the Horizon] -- was to achieve much more of a European flavor in the handling.
"And we believe that's been achieved," said Pedersen. "Compared to domestic models in their class, the LH's will handle significantly better and still ride better.
"But that doesn't mean we sacrificed ride to get better handling," he continued. "Actually we raised the level of both with these vehicles. I'd say the cars are a couple orders of magnitude improvement in handling and maybe a single order of magnitude improvement in ride quality."
In establishing the LH ride and handling characteristics, engineers benchmarked several competitive models, primarily what they considered two top-tier models in the same segment, the Ford Taurus and Nissan Maxima. The Acura Legend, Toyota Camry, Lexus ES300, and the BMW 5 Series also were targets, but to a lesser degree.
Intrepid, Concorde and Vision will be equipped with one of three levels of suspension, depending on model and customer choice. Pedersen offered this assessment of each:
BASE -- This suspension was developed specifically for an entry-level vehicle that has a sporty handling feel, but not necessarily in competition with the more expensive"benchmarked" competitors. As good as Taurus or Lumina, however, and better in several respects.
TOURING -- Superior to Legend or Maxima in terms of any handling parameter.
PERFORMANCE -- Lifts LH's to the level of being one of the best handling sedans in the world. Its handling performance rivals the likes of BMW 5 Series, Audi 1 00 and Mercedes S.
Base suspension availability is confined to the Intrepid and Concorde, with the Touring Package an option. The Intrepid buyer can also opt for the Performance Package. The Vision has the Touring Package suspension standard with the Performance Package suspension an option.
Certain chassis/body elements obviously work in combination to provide the LH's with their own, unique ride and handling characteristics.
LH's power rack-and-pinion steering design, with its bias toward European standards, is a prime example. It has a ratio of 1 7:1 in all model applications.
The steering feels more "connected" than previous American cars, according to Pedersen, who described the LH's as having neutral steering. "That's not to say it isn't maneuverable or feels heavy," he explained. "Younger drivers in particular prefer steering with a tighter, somewhat higher turning effort. It gives them the initial sense that the car will handle better at higher speeds.
"At the same time, that extra effort won't discourage older drivers, either," he added."People who are used to the traditional, full-size American cars will appreciate the difference once they've experienced the added security the steering and handling provide."
Despite its 113-inch wheelbase and 62-inch track, the curb-to-curb turning diameter on LH is only 37.6 feet, less than many competitive cars with smaller overall dimensions.
A good part of this is due to the longitudinal, forward-mounting of both engine and transaxle. On most front-wheel drive cars, the transversely-mounted transaxle protrudes slightly into the left front wheel well, thereby expanding the turning diameter of the car.
The sturdy body structure of all three LH models -- torsionally, the stiffest Chrysler has ever built -- also contributes significantly to its world-class ride and handling attributes.
"Intrepid, Concorde and Vision will be among the most 'shake-free' cars on the road today," ventured Pedersen. "Only a few of the most expensive German models can compare."
LH's will employ larger tires than most competitive sedans in its class, a feature also designed to help achieve a superior ride and handling profile.
"Based on the weight of these cars, the tires for every suspension level actually could be one size smaller," said Pedersen. "But with the larger tires (15-inch standard, 1 6-inch optional) you're using less of the tire capacity to handle weight, so more is available for improved ride and handling."
LH's hydroelastic engine mounts, fitted to an isolated engine cradle, reduce the amount of engine vibration that enters the body of the car and allows for a smoother idling quality when the vehicle is stopped.
In addition, if the car hits a bump in the road under speed, the mounts permit slight engine shifting, but the resultant vibration is damped instead of being transferred to the car body and ultimately to the driver.
LH engineers implemented a front suspension design that separated the directional motions of the bushings -- fore and aft or laterally.
"Generally, you want to make the fore/aft direction of the wheels to be fairly soft so, as a wheel hits a bump, the wheel recesses and you don't feel the harshness in the car," said Pedersen.
"But, at the same time, you don't want to have the bushings too soft in a lateral (movement) sense so that when the car rounds a corner, the outer wheel moves inboard."
Thus, the LH chassis design positions a strut at all four corners. For the front suspension, a fore/aft"tension strut" is rubber isolated on both ends to provide the soft fore/aft wheel motion. A lateral link has a very stiff inner pivot bushing to keep the wheel from moving laterally inboard,
"We tried to separate the motions and purposes of all the bushings in the suspension," explained Pedersen. "We did the same with the rear suspension."
When it all comes together on the LH assembly line -- the independent four-wheel suspension, longitudinally-mounted engine and transaxle, exceptional body stiffness and over-sized tires -- the ride/handling profile of these cars may not only be world-class, but put them truly in a class by themselves.
Body and safety features - Dodge, Chrysler, Eagle
Already considered industry models for forward-thinking design, engineering and manufacturing techniques, the 1993 Dodge Intrepid, Chrysler Concorde and Eagle Vision also are the most safety- conscious cars the company has ever produced. And that's from a company known for its industry- leading safety technology.
Each will embody the latest technology available to afford passengers in this new generation of passenger cars the maximum security in accident or accident avoidance situations.
Features offered will include anti-lock brakes, traction control, standard dual air bags for both driver and front-seat passengers, an integrated child restraint seat, collapsible steering column, more comfortable and effective shoulder restraints that adjust to the height of the occupant, as well as improved seat-mounting structure.
The body structure of Intrepid, Concorde and Vision is stiff but light, as a result of extensive up-front structural analysis by Chrysler's super computer.
'These are the strongest body structures we've ever had on a Chrysler car," contended Dennis Renneker, executive engineer -- Body-In-White and Chassis for the Large Car Platform Team.
The goal for LH's body structure was to have two basic characteristics -- world-class front-to-rear torsional rigidity with no torsional bending in the middle.
LH body engineers targeted the Nissan Maxima as the benchmark for torsional stiffness and body- bending resistance.
"The Maxima has a smaller wheelbase and a narrower track than LH so we had a bigger job," recalled G. Glenn Gardner, general manager -- Large Car Platform Engineering. "We wanted to equal or surpass it. How did we do? Torsionally, the LH is 25 percent stronger than Maxima, even with LH's larger dimensions."
Computer model simulation also was used extensively in LH's crash/collision development, which provided engineers a solid foundation in designing an actual vehicle that passed Chrysler's barrier test on its first attempt.
Renneker said Chrysler engineers would never abandon real-world, controlled crush tests to determine the crush characteristics of a vehicle, but the computer simulation was a definite advantage.
"We used it to analyze crush on the front, sides and back of the LH," he said. "Ten years ago, it wouldn't have been possible. Today, we're actually using it as a working development tool."
Also making a significant contribution to LH's crash/collision resistance are the straight-through underbody rails permitted by the longitudinal,"north-south" positioning of its engine and transaxle. In most front-wheel passenger cars, the engine and transaxle are mounted transversely, which causes the left rail (on U.S. cars, right rail on many Japanese units) to be bent up and over the transmission en route to the front bumper-end of the car.
"That's a natural place for the rail to buckle and collapse on frontal impact," noted Gardner. "With the LH, we have a nice straight rail. It comes right off the floor pan straight forward so when the car goes into a barrier, you don't have the same concerns. With one bent rail, if it collapses, the vehicle may twist and collapse on the driver's side. Straight rails provide a uniform crush and make it easier to manage frontal impact."
Renneker confessed some early concerns that moving the LH's rear wheels closer to the corners of the vehicle might create a penalty, but it didn't affect the body structure at all.
"We had to be careful designing the front structure, though" he said."It was a tough challenge, particularly with regard to the air bag systems. We had to be doubly sure the sensors would go off at exactly the right impact speeds and also that the deployment of the air bags had the right trajectory."
The standard-feature air bag system on Intrepid, Concorde and Vision is unique from others currently in use. It allows venting of inflating gases through the porosity of the fabric instead of two or more discreet vent holes, thus reducing smoke levels in the car once the air bag deploys.
"This design also minimizes the possibility of localized 'hot spots' which may be annoying," said Donald Goodwin, executive engineer of Interior Engineering for the LH Platform Team.
Still another added feature of the LH air bags provides a gas generant release system so rapid that full deployment is achieved before the occupant makes contact.
"The passenger side air bag (which can help protect two front-seat occupants) emerges from over the top of the glove box on the instrument panel," explained Goodwin."It's fully deployed in 1/20th of a second."
Lower surfaces of the instrument panel of all three LH models function as a knee bolster in a frontal impact and restrains the occupants' lower extremities against excessive forward motion.
The optional integrated child seat feature for LH cars includes a booster for larger children -- those above the 45-pound weight threshold and up to sixty pounds -- by using the base of the child seat and the regular seat back.
On all LH models with power windows, an override switch on the driver's control panel will shut off power to the other windows to prevent undesired operation by other occupants, particularly small children.
First Generation Chrysler LH Series Information at Allpar
- Main first-generation Dodge Intrepid, Chrysler Concorde / New Yorker / LHS, and Eagle Vision page
- Performance upgrades and common repairs
- Dodge Intrepid, Chrysler Concorde, and Eagle Vision styling development
- Climate control and engine cooling systems
- LH body shell and suspension: performance, comfort, and safety
- Interview about LH packaging and design with G. Glenn Gardner
- Interview about LH design with Francois Castaing
- Definition and advantages of cab forward (how cab forward was developed, and an interview with Tom Gale.)
- 80-mpg Intrepids: ESX and ESX-2
- Design and manufacturing process for the LH series: innovations in the engineering and involvement process
- Step-by-step guide to repairing the LH steering
- Step-by-step guide to replacing the hub and bearing
- Components: 3.3 liter and 3.5 liter V6 engines • Four-speed automatic transmission
- Dodge Intrepid, Chrysler Concorde/New Yorker/LHS, Eagle Vision Specifications