2006 Pontiac Solstice Architecture & Suspension
SOLSTICE ARCHITECTURE & SUSPENSION
In keeping with the spirit of a pure sports car, Solstice is designed to feel like an extension of the driver’s body. It is built on GM’s new global rear-wheel drive compact performance architecture, which uses a hydroformed chassis as the foundation of a strong structure. Independent short/long arm-type suspensions in the front and rear are mounted to the chassis and give Solstice a direct, road-gripping driving feel. Driver-focused features also include:
- Bilstein coil-over monotube shocks at all corners
- Rack-and-pinion steering (power assisted)
- Eighteen-inch aluminum alloy wheels
- P245/45R18 all-season tires
- Large, four-wheel disc brakes, with 11.7-inch (297 mm) front rotors and 10.9-inch (277 mm) rear rotors
The foundation for Solstice’s responsive suspension system is a lower-dominant tube structure for the chassis. Hydroformed frame rails, which run the full length of the vehicle, are the basis of the chassis, while additional stampings form a rigid structure onto which the bodywork is attached. The hydroformed tube structure, which runs from the front bumper, through the left- and right-hand frame tubes and all the way to the rear bumper, provides an extremely strong foundation. Hydroformed tube structures have typically been used in light-duty truck frames and in some front-wheel drive vehicles, but Solstice is one of only two vehicles to feature an entire hydroformed chassis – the other being the Chevrolet Corvette.
The hydroforming process uses pressurized fluid to form each frame rail from a single piece of steel, rather than several pieces of steel welded together. This creates a stronger frame rail and requires less time to form it. Also, it provides a high strength-to-weight ratio, with additional components and stampings are added to the frame rail during vehicle assembly. A unique assembly method was adopted for the production of the chassis, with extensive use of MIG (metal inert gas) welding. Where typical automotive sheet metal assembly typically uses spot welding because of its speed through automation, MIG welding was selected to attach brackets and other chassis and body structures because the hydroformed frame tubes don’t allow access on the inside of the tube – and spot welding requires access to both sides of a piece of metal to create a weld. Although more time intensive, MIG welding allows parts to be joined with access to just one side.
A tunnel at the center of the chassis, which houses the transmission and driveshaft, is internally reinforced and enclosed at the bottom to enhance stiffness. This built-in strength reduces chassis flex and cowl-shake in a vehicle designed from the outset as a convertible. Solstice’s bending frequency is 20.9 Hz and the torsional frequency is 18.8 Hz –figures that compare with competitors at the top of the segment.
The strength of Solstice’s lower-dominant architecture means the body doesn’t have to carry much of the vehicle’s strength. This allowed for more exterior design flexibility, while also enabling precise suspension tuning.
Suspension details
The architecture’s rigid structure also permits more precision when it comes to tuning the suspension, as engineers don’t have to account for chassis flex. The short-long arm suspension design features forged aluminum upper and lower control arms that are strong and low in mass. The rear suspension also features a toe control link and the rear differential housing has an optimized three-point mounting design. Bilstein monotube shocks are used at each corner and provide immediate and controlled damping.
Solstice’s responsive suspension is linked to the road via 18 x 8-inch aluminum alloy wheels and P245/45R18 all-season tires. The wheels are mounted at the outer corners of the vehicles, enhancing grip and giving the vehicle an aggressive stance. The five-spoke wheels come standard with a painted finish and a bright polished version is available.
Four-wheel disc brakes are standard and consist of 11.7-inch (297 mm) ventilated front rotors and 10.9-inch (277 mm) rear rotors. ABS (with dynamic rear proportioning) is available. Power-assisted rack-and-pinion steering is standard. It features a 16.4:1 ratio and requires only 2.7 turns, lock to lock. The steering system is tuned to provide a confident “on center” feel and delivers excellent driver feedback, further enhancing the driver’s feeling of being connected to the road.
Additionally, engineers executed the following dynamic details to enhance Solstice’s overall feeling of refinement, balance and performance:
- A near 50/50 weight distribution provides a balanced handling feel
- Hydraulic engine mounts are used to provide a smoother engine feel
- An optimized acoustic barrier and sound absorption package to provide world-class levels of interior quietness
- Tires selected for handling performance and low noise.
