Pontiac G8 built on GM’s new global RWD architecture
The 2008 Pontiac G8 performance sedan is built on GM’s new, global rear-wheel-drive architecture. With the input of Pontiac and GM North America, the G8 was developed in Australia, under the direction of Holden’s engineering department.
Taking advantage of GM’s global centers of engineering expertise, a series of vehicle architectures are being developed that can be easily adapted to the unique vehicle requirements of various regions. For example, global truck architectures are being developed in North America while midsize vehicle architectures are created in Europe.
“The rear-wheel drive engineering team has put together a simply spectacular car that captures the essence of Pontiac,” said John Larson, Pontiac general manager. “We believe that the Pontiac G8 will rival competitors costing far more.”
The Holden-engineered global rear-wheel drive architecture was designed to deliver world-class levels of strength and refinement, along with crisp driving dynamics, while serving as the foundation for vehicles sold in a wide variety of climates and road conditions around the world – from the desert-like desolation of Australia’s Outback to the frost-heaved highways of North America’s cold regions.
“We set out to lift the bar on what could be achieved with quality and refinement,” said Tony Hyde, Holden executive director of engineering. “We have gone over this car time and time again to reduce gaps and margins, ensuring that every fit is crisp and tight.”
For North American customers, the result is a tautly-designed rear-wheel-drive performance sedan that is ideally suited for Pontiac customers.
“We spent many hours refining the chassis to create that unique blend of steering precision, vehicle balance and handling that we believe driving enthusiasts will love,” said Doug Houlihan, G8 chief engineer.
Global, balanced architecture
The new global rear-wheel-drive architecture used for the G8 was designed to accommodate production for both left-hand drive and right-hand drive markets around the world. To ensure durability for the vast array of driving conditions and climates, the new architecture was designed with a robust, protected electrical system, superior climate control system and noise/vibration-isolating suspension systems.
Among the new architecture’s design attributes is a layout that promotes a nearly 50/50 front-to-rear weight balance ratio, thanks to design features that include a steering rack mounted ahead of the front axle, engines mounted low and rearward in the front chassis cradle and a rear-mounted battery.
GM’s new rear-drive architecture has an exceptionally strong unitized chassis/body structure, including advanced-strength steel used in more than 80 percent of its construction. This strong foundation enables several factors than benefit the G8’s driving experience, including smoother, more solid ride characteristics and more precise suspension tuning, as the stiffer structure allows engineers to tune the suspension without having to account for chassis flex.
The stiff structure also enhances safety, as it helps absorb crash energy through a multiple load path strategy that includes optimized front-end and rear-end deformation zones. (See safety section below.)
Chassis and suspension
A unique, four-wheel independent suspension system is integrated with the G8’s structure, and is the result of eight years of development. It uses the strength of the body structure to enhance the driving experience through optimized steering, handling and driving control.
The G8 rides on a long, 114.8-inch (2,915 mm) wheelbase, with the wheels set wide on 62.7-inch (1,592 mm) front and 63.3-inch (1,608 mm) rear tracks. The front suspension features a multi-link, strut-type design that incorporates a direct-acting stabilizer bar, while the rear suspension uses a four-link independent design, with coil springs over shocks and a decoupled stabilizer bar.
The front suspension uses a hydraulically damped bushing on the forward end of the tension link for improved ride isolation. The lateral link feature a rubber spherical joint that enhances lateral stiffness. Camber, caster and toe are fully adjustable.
With the rear suspension, a high degree of lateral stiffness is achieved with the use of two lateral ball joints per side. A rubber-damped suspension frame further isolates the body structure from noise, vibration and road harshness.
Steering and braking
The steering rack is mounted forward of the front axle centerline – with dual lower links and individual ball joints at the outer ends – which enhances the balanced feel of the car while also contributing to a more direct steering feel. Steering rates are tuned specifically for the V-6-powered base and V-8-powered GT models.
Matching the vehicle’s handling and steering agility is a carefully tailored brake system that uses four-wheel discs sized to match each model’s performance. The higher-performance capability of the V-8-powered GT, for example, has larger brakes than the V-6 base model. The brakes are integrated with a standard electronic stability control system.
The basic brake design for all models includes twin-piston front alloy calipers and vented disc rotors, and single-piston, alloy rear calipers with vented disc rotors. ABS is standard.
Safety was one of the foremost goals in the design of the G8’s architecture. It combines a sturdy, crash-absorbing body structure and state-of-the-art passenger protection technology. Examples of these elements include:
- Efficient, energy-absorbing front structure and a strong occupant safety cage
- Six standard air bags, including dual-stage frontal air bags, thorax air bags for front-seat passengers and roof rail-mounted head curtain air bags for both seating rows
- Multiple air bag sensors: two electronic front sensors and two side-impact sensors, all connected to a sensing diagnostic module
- Front safety belts with load limiters and dual pretensioners
- Ride-down steering column and breakaway pedal system
- Four-wheel disc brakes with ABS.
An electronic stability control system is standard on all models, as is full-function traction control. These features bolster driver control during certain driving conditions, which can help avoid a crash.
Safety development included tests that represented occupants ranging in size from a six-month-old baby to a 95 th percentile adult male. Sixty-one physical vehicle safety tests were performed with the variety of test dummies, which helped optimize the structure’s front and rear crush zones.
GM’s global rear-wheel-drive architecture underwent some of the longest and most stringent testing and validation procedures undertaken by General Motors, which helped ensure its strength, safety and reliability in markets around the world. These procedures included:
- More than 2.1 million miles (3.4 million km) of equivalent road evaluation
- Approximately 5,000 hours of virtual safety tests
- Seventy-nine physical safety tests
- Approximately 41,000 hours of electrical system tests
- Approximately 11,000 subsystem validation tests and activities
The G8’s new rear-drive architecture also incorporates a host of design and technology details that bolster comfort, convenience and quality. They include:
- A new electrical system that supports OnStar and XM Satellite Radio
- A rear-mounted battery that offers increased protection from the elements and improves vehicle weight distribution
- A contemporary “down and forward” instrument panel design that enhances outward visibility and provides a roomier, airy cabin environment
- An all-new climate control system with multiple heating/cooling ducts, up to 20 fan speeds in the base configuration, and infinite speed settings in the optional dual zone climate system
- A new family of premium radio systems with available color screen display
- A unique four-bar deck lid hinge design reduces trunk space intrusion for increased cargo capacity.