A major objective for the Jeep® Liberty’s engineering team was to improve the vehicle’s on-road performance without sacrificing its off-road capability – after all, it’s a Jeep! Instead, Jeep engineers set out to improve the vehicle’s on-road refinement and strengthen the vehicle’s off-road abilities. As a result, an all-new independent front and five-link rear suspension systems, along with the all-new Selec-Trac® II full-time four-wheel-drive system, give the all-new 2008 Jeep Liberty its refined on-road handling without compromising the vehicle’s off-road attributes.
“The all-new 2008 Jeep Liberty will continue to remain a segment leader by delivering a balance of on-road refinement and off-road capability,” said Craig Love, Vice President – Rear-Wheel Drive Product Team, Chrysler Group. “Whether it’s an off-road adventure or the daily commute in rush-hour traffic, Jeep Liberty owners will feel confident and comfortable behind the wheel.”
All-new Independent Front Suspension and Five-link Rear Suspension
An all-new independent front suspension, all-new five-link rear suspension and a power rack-and-pinion steering system contribute to the all-new 2008 Jeep Liberty’s blend of on-road ride comfort and nimble, confidence-inspiring handling.
The independent short and long-arm coil spring front suspension provides drivers with an optimum combination of ride, handling and a steering feel that is unattainable with typical strut-type suspensions. A link-type stabilizer bar helps control body lean in cornering and lane-change maneuvers. Ample wheel travel and tuned jounce bumpers help maintain the vehicle’s consistent ride quality. A low-arm design mounts the upper control arm on the longitudinal rail of the front body structure for optimum stiffness to minimize noise, vibration and harshness.
A new five-link rear suspension, including upper and lower trailing links and a track bar, provides greater lateral stiffness, making the vehicle feel more responsive. The solid axle delivers uniform handling and stability when the vehicle is loaded or towing a trailer.
Precise Rack-and-pinion Steering
To help create a premium on-road driving experience and confident road feel, Jeep Liberty engineers focused on the vehicle’s steering. The power rack-and-pinion steering imparts a precise feel and provides a turning circle similar to vehicles with a shorter wheelbase.
Two Four-wheel-drive Systems
Whether it’s rock-crawling in Moab, Utah or making your way through a snow-covered highway, the all-new 2008 Jeep Liberty’s four-wheel-drive systems will meet customer needs. Available for the first time is the all-new Selec-Trac II full-time four-wheel-drive system, and also offered is Command-Trac®, a part-time four-wheel-drive system.
All-new Selec-Trac II Full-time Four-wheel-drive System
The all-new Selec-Trac II four-wheel drive system is a full-time, active on-demand system that anticipates and prevents wheel slip before it occurs. It is ideal for a wide range of road settings, including dry pavement conditions not typically suited for conventional part-time four-wheel-drive systems.
This premium system offers a “4WD Auto” mode that is ideal for full-time driving. When driving in 4WD Auto mode, the system uses vehicle sensors to adjust and redirect torque between the front and rear axles based upon real-time driving conditions, providing the vehicle with responsive tractive performance.
For added capability when traversing steep grades, rough terrain or extremely poor traction surfaces, the transfer case includes a “4WD Low” mode. This second speed gear multiplies engine torque 2.72 times and locks the clutch pack for maximum traction.
Electric shifting between 4WD Auto and 4WD Low is accomplished with a console-mounted switch. A “2WD” mode is provided for the U.S. markets. A pushpin button is used to shift to Neutral mode. Selec-Trac II is available on all Liberty models.
Command-Trac Part-time Four-wheel-drive
Command-Trac is a part-time four-wheel-drive system; its front driveline is disengaged from the transfer case and power is directed to the rear wheels.
“2WD High” is the vehicle’s everyday driving mode. By selecting “4WD Lock,” located on the console, the front and rear driveshafts lock together so that the two rotate at the same time providing a 50 front/50 rear torque split. It is for use only on slippery or loose surfaces, such as snow or dirt. It can be engaged at any speed.
A Neutral mode permits towing without having to disconnect the drive shafts. A pushpin button is provided to shift the transfer case into Neutral.
For true off-road conditions, “4WD Low” can be engaged at speeds of 2-3 mph. The front and rear drive shafts are locked together, and a second gear set multiplies torque providing traditional Jeep capability.
Jeep Trail Rated®
The Jeep Liberty’s four-wheel-drive systems are Trail Rated. The Jeep Trail Rated® badge on the 2008 Jeep Liberty shows that the vehicle has been designed to perform in a variety of challenging off-road conditions identified by five key consumer-oriented performance categories: Traction, Ground Clearance, Maneuverability, Articulation and Water Fording.
Jeep Trail Rated is a unique methodology used by Jeep Engineering to measure and predict off-road performance for all Jeep vehicles today and into the future. Through a combination of natural and controlled field tests, Jeep Trail Rated provides a consistent measurement of off-road performance for all Jeep vehicles. Only Jeep vehicles are Trail Rated.
Proven 3.7-Liter SOHC V-6 Engine
The 3.7-liter SOHC V-6 engine is standard on all Jeep Liberty Sport and Limited models in the United States The 3.7-liter SOHC V-6 engine provides the 2008 Jeep Liberty with competitive peak power and torque while providing smooth, quiet operation and proven durability. It produces 210 hp (157 kW) @ 5,200 rpm and 235 lb.-ft. (319 N•m) of torque @ 4,000 rpm. Fuel economy has been improved and now achieves an estimated *16 city (18 mpg using 2007 EPA standards), and *22 mpg on the highway (23 mpg based on 2007 EPA standards).
Refinements in the valve train and combustion chamber, working together as a system, enhance low-speed torque while providing a smooth idle and minimal engine noise. A sophisticated Electronic Throttle Control system helps to improve drivability and acceleration feel. The exhaust gas recirculation valve helps to increase the engine’s fuel economy.
Towing capacity on all models is up to 5,000 lbs. when properly equipped with a weight distributing hitch.
For key diesel markets outside North America, the Jeep Liberty (Cherokee) will be offered with an all-new 2.8-liter DOHC 16-valve common rail diesel engine.
*Based on new 2008 model year EPA methods
Manual and Automatic Transmissions
Two transmissions are offered on the Jeep Liberty in the United States: a six-speed manual transmission and a four-speed automatic transmission.
The six-speed manual transmission is standard on the Jeep Liberty Sport 4x2 and 4x4 models. It provides optimal shift quality, quiet operation and high quality. All ratios are synchronized, including Reverse. Short throws are accompanied by low shift efforts through the use of multiple-cone synchronizers on first through fourth gears, and triple cones on first and second gear and double cones on third and fourth. The 3-4 synchronizer mounts with the cluster gear on the countershaft to minimize shift effort by lowering inertia. State-of-the-art synchronizer materials ensure a constant coefficient of friction throughout the service life with high-wear resistance. For precise shifting, a multi-rail shift system is used. Hard-finished gears allow for quiet operation. The two-piece aluminum case with integrated clutch housing contributes to powertrain stiffness and light weight.
Transmission ratios for the six-speed manual are:
The four-speed automatic transmission is standard on the Jeep Liberty Limited 4x2 and 4x4 models and optional on the Jeep Liberty Sport 4x2 and 4x4 models. The transmission incorporates a variable hydraulic line pressure feature to increase fuel economy.
Transmission ratios for the four-speed automatic are:
Traditional Tough Testing
Maintaining the Jeep Liberty’s reputation as one of the brand’s most consistent and solid performers in outside quality metrics was not a challenge taken lightly when the engineering corps took on the assignment for the all-new 2008 model.
The 2008 Jeep Liberty was designed and engineered under the Chrysler Development System (CDS), the comprehensive, coordinated and disciplined product creation process that improves quality and speed-to-market while reducing costs and encouraging practical innovation in new products.
Emphasized on CDS are the systems engineering, design and up-front planning to avoid time-consuming and costly trial-and-error or changes during the latter phases of the product development cycle. With CDS, all product and process planning is completed and fully integrated before production tooling begins.
In addition, CDS has been enhanced by the Quality Gates process, adopted as part of the best-practice synergies produced by the DaimlerChrysler merger. Prior to the merger, Chrysler utilized the Chrysler Development System to ensure quality from the vehicle’s sketch stage in Design, through concept and prototypes to testing and ultimately to production at the plant.
However, the merger allowed the inclusion of the Quality Gates process, a system that requires a 12-step checks-and-balance review of the project at critical stages of development by senior management.
As part of the process, the 2008 Jeep Liberty logged nearly seven million customer equivalent miles that included durability and reliability testing on pre-production models and in the form of endurance driving with senior management.
The pre-production models saw extreme testing at such traditional Jeep gauntlets as Moab, Utah, Death Valley, Colorado, Manitoba, Indiana and Pennsylvania to evaluations on off-road capability, high and low grades, trailer towing and ambient temperatures. Those extreme weather conditions included temperatures from -40F to more than 110F.
The 2008 Jeep Liberty is produced at the Toledo (Ohio) North Assembly Plant.