Innovative Retractable Hardtop System Assures Open-Air Styling Without Sacrificing Utility

One of the most distinguishing features of the all-new 2003 Chevrolet SSR is an ingenious power retractable hardtop system that provides an open-air driving experience without impeding the vehicle's truck-like utility.

The retractable hardtop on the SSR is the first ever applied on a pickup-styled vehicle. It is the only system of its kind to go into production, where the roof panels with linkages to "stack" vertically behind the passenger compartment — a design that enables quick operation and minimal stowage requirements.

A single button on the console transforms the SSR from an enclosed roadster to a convertible in less than 30 seconds, neatly tucking the roof panels rearward in waterfall fashion between the passenger compartment and cargo area. The unique vertical storage system is an important enabler for the vehicle's ability to emulate the utility of a pickup — even with the top down, the SSR's bed capacity remains unchanged.

"As far as we know, this is the only retractable hardtop system with roof panels that operate without a center hinge, held together only by the linkage, as they move," explained Gary Forgue, chief engineer for the retractable roof system.

"Other known production systems use panels hinged together that 'clamshell' as they retract or deploy, but due to space requirements, we needed to develop a system that stowed vertically. We didn't want to compromise the vehicle's cargo bed utility." According to Forgue, most of the major components of the top system are packaged as an assembly — this brings a number of benefits including reduced vehicle build complexity, enhanced cross-vehicle structural rigidity, and easy service of the system.

"The system is assembled off-line during the manufacturing process and includes a structural bulkhead that's been designed into the SSR's upper body structure between the cargo area and the passenger compartment," Forgue explained. "Once it's attached with ten bolts, it literally becomes a structural element of the vehicle and brings enhanced cross vehicle rigidity."

The design process for the SSR's retractable roof system was completed in about four months — a remarkably quick turnaround considering the level of innovation incorporated. A team of engineers from General Motors, ASC Incorporated, and Karmann USA developed the system, which has been designed for long-lasting, reliable performance.

Operation
Via depression of a single button, the SSR is transformed into a convertible in a smooth, quiet kinematic sequence orchestrated by the system's controller using information collected from a series of sensors.

The button that actuates the sequence must remain depressed until the entire event is complete...releasing it at any time temporarily halts the process.

The following outlines the sequence of events:

• Initially, the controller automatically lowers the driver and passenger side windows to ensure they are clear from seals in the roof panels. As soon as the windows are clear of the seals, the rest of the process begins.
• Latches release the system's tonneau, a body-color panel stretching the full-width of the vehicle between the passenger compartment and the cargo area. The tonneau swings up to a near vertical position, then latches release the forward roof panel from the header (top edge of the windshield).
• As the top panels begin to cycle down, a body-color section called the "flipper door" moves upward from its vertical position in the storage area to allow the top to pass by.
• As they cascade downward and rearward, the two top sections separate and nest rear-underfront as they retract vertically into the storage area.
• The flipper door and tonneau then close over the panels. Together with the fixed body-color "waterfall" panel, which ties the tonneau to the interior between the seats, they close the top storage area completely for a smooth, flush appearance.
• A series of latches in the storage area holds the mechanism securely down and locked in place for rattle-free stowage. The latches can be overridden so the top can be manually lifted, deployed and secured in the unlikely case of a power failure.

Just as with the top-down process, pushing and holding the button converts the SSR back to a closed-cabin roadster. If the windows are up when the cycle starts, the controller lowers them to allow the top to find its true position without interference from the door glass and then returns them to the up position.

The controller also has the capability to "index" the door glass position. For example, when a door handle is pulled with the glass up, it drops the glass in that door just slightly to clear the seals. When the door is closed, the glass comes back up against its seals.

Quality & Durability
In both development and assembly, the retractable top system on the SSR goes through rigorous testing for optimal, dependable performance.

The tests are conducted "off-line" which enables focused functional evaluation and durability testing. The system is validated based on the testing for durability far beyond the expectations of a normal vehicle lifetime. Extensive water testing is conducted on the system both as an assembly and as assembled on the vehicle.

Off-line assembly and low volumes enable opportunities for increased quality assurance. System durability is enhanced through the following:

• Roof panels made of heavier gauge steel stampings.
• The linkage bars are 6.3 mm steel for strength and rigidity.
• A well-isolated electro-hydraulic power system, combined with strategically located bushings, eliminates metal-to-metal contact for long life and smooth, quiet operation. The bushings protect the integrity of the linkage joints so the fits do not change over time. This helps minimize chances for looseness or rattling.
• Optimized design and assembly helps reduce wind noise in the cabin with the top up, and a wind break will be offered, as a GMPO Accessory, that fits between the seats and buffers turbulence with the top down at highway speeds.

All-Aluminum Vortec 5300 Engine/Hydra-Matic 4L60-E Automatic Transmission Delivers Performance.

The Chevy SSR features a proven General Motors powertrain, including the first application of GM's new aluminum-block Vortec 5300 V8 engine coupled to the Hydra-Matic 4L60-E electronically controlled 4-speed automatic transmission. Output and fuel economy data have yet to be finalized. Here are additional details on the key attributes of the SSR powertrain.

Lightweight Aluminum Construction. The engine block is 45.4 kilograms (100 pounds) lighter than the current Vortec 5300. Cast of 319-T7 aluminum alloy, the engine capitalizes on the lower mass and superior thermal efficiency of aluminum.

Durability.
The all-aluminum Vortec 5300 V8 builds on the small-block tradition started by the 5.7-liter V8s featured in the Chevrolet Corvette. The engine block is produced by the gravity-poured precision sand casting process. This process allows cylinder liners to be cast in place and yields exceptional cast quality. The engine is tested to identical levels of endurance as the cast iron Vortec 5300 engine.

Quietness.
The engine features new quiet-profile pistons to ensure that the pistons track straight in their bores, minimizing clearances as the pistons rock under gas pressure.

The pistons are polymer-coated to reduce cold scuffing and engine noise. Polymer-coated pistons, long a mainstay in luxury car engines, enable tighter bore clearances, provide enduring wear surfaces between pistons and cylinder walls, and further reduce piston motion.

Proven Engine Design.
The aluminum Vortec 5300 benefits from the design of the latest version of the cast-iron 5.3-liter V8 in a variety of ways.

The deep-skirt engine block design, with six-bolt main bearings, allows cross bolting of the bearing caps, limiting crank flex, stiffening the engine's structure and reducing overall vibration.

In addition to the aluminum block the V8 garners other mass reductions through use of a new oil pan design. Due to the lower, shorter design of the SSR, the new "pan-axle" design allows the front differential to pass through the oil pan, resulting in weight savings, while optimizing the use of under-hood space.

Exhaust catalyst and emissions control system calibration have been improved to allow the engine to meet federal emissions and California Ultra Low Emissions Vehicle (ULEV) standards without an Exhaust Gas Recirculation (EGR) system.

The aluminum engine, like its iron sibling, uses platinum-tipped spark plugs to extend plug life up to 100,000 miles, while the coolant maintains its cooling and corrosion-inhibiting properties for up to 150,000 miles. Scheduled maintenance is limited to oil changes when indicated by the engine oil life monitoring system or at 10,000 mile intervals (whichever comes first).

GM's small block engines continuously prove that cam-in-block aluminum engines meet the performance and durability demands and increasingly stringent emissions standards of a new century.

Hydra-Matic 4L60-E Automatic Transmission.
Transferring power to the rear wheels is done via the Hydra-Matic 4L60-E transmission. The 4L60-E, also used in GM trucks and the Chevrolet Corvette, was selected for its durability, low weight, and the ability to optimize its electronic controls for performance oriented shifting. The electronic controls are calibrated to give the dependability of a pickup and the performance of a supersport vehicle.

To multiply engine torque, the 4L60-E uses a 300 millimeter torque converter. The converter is enclosed in a 360-degree-mount structural bell housing for powertrain rigidity. Overall transmission weight as shipped from the Toledo, Ohio, transmission assembly plant is 88.3 kilograms (194.6 pounds).

In the Beginning . . . How GM Design Created the Chevy SSR.

The Chevy SSR evokes Chevy's rich heritage. But the original SSR concept vehicle owes its origins to very new and innovative methods of creating and designing vehicles.

The creation of the concept vehicle marks the beginning of GM's new process to get fresh, exciting concepts from the computer, to the auto show and to the showroom.

SSR traces its lineage to the vision of Wayne Cherry, Vice President of GM Design. The original idea was to explore how a heritage design theme might manifest itself in a truck, as opposed to cars where heritage designs abound. Working with GM Design's Corporate Brand Character Center, which defines and executes the vision for each of GM's global brands, Cherry immediately made the connection to Chevrolet as a perfect fit for a heritage-inspired truck.

Ed Welburn, executive director of the Brand Character Center, led the effort to develop some options as to what this heritage truck might become. In the summer of 1999, a team of young designers began rendering creative ideas.

"The heritage of Chevy Trucks is so rich and diverse that the team quickly found numerous ways to design a heritage truck in way that wasn't simply a remake of a prior design, but rather a modern interpretation," Welburn says.

Four options emerged. Three were inspired by various eras of Chevy pickups, the '30s, late '40s and early '50s and the late '50s. A fourth was a futuristic design with more subtle heritage cues. Of those original four, two were selected by Welburn to go from sketches and digital designs to full-size physical models. The two ideas were the late 40's/early-50's inspired pickup and the futuristic design, dubbed "Nostalgia 2000." However, an idea from one of the designs not selected stuck in Welburn's mind.

"One of the options included an open-air cab," Welburn says. "We were intrigued by the more contemporary and fun attributes of this type of vehicle, so the idea of a pickup truck that was also a modern convertible roadster held great promise."

The sleek, "slammed" design inspired by Chevy's Advance Design 1947-1952 pickups – with the critical addition of a retractable hardtop – gained momentum as the designs went to clay. Many other tweaks and enhancements were quickly made to hone the styling further. The team paid particular attention to the vehicle's large flared fenders, sculpted hood and rear accented stance. The combination of heritage cues mixed with a fresh take on a roadster proved irresistible.

"The result was a form that was very car-like, contemporary and relevant to today's customer," Welburn says. "Also, we were able to design the vehicle in a way that enhances the current and future Chevrolet brand character, rather than simply paying homage to the past."

In August, Wayne Cherry and Tom Davis, then Vice President of the GM Truck Group, reviewed the team's work and authorized the SSR be built for the 2000 auto show circuit. Designers developed the vehicle solely using math-based digital tools, in preparation for the January 2000 Detroit Show.

Once the SSR concept vehicle was unveiled, the reaction was instant and positive. While the press and public experienced the vehicle for the first time in the auto show circuit in the first half of 2000, GM designers were already thinking of the future.

"From the start, the SSR concept was designed to be a viable option for production," Welburn says.

This enabled the team to move quickly when, in August of 2000, the vehicle was put in GM's future production plan officially.

The program then moved seamlessly to GM Design's production studio, under the direction of Vehicle Chief Designer Bill Davis. The team's marching orders were straightforward – make sure the production SSR matches the original concept as closely as possible. The new production-intent show vehicle, built in August of 2001, represents the essence of the team's journey from concept to reality.

Stirring Concept Becomes Reality. Production-Intent Show Vehicle Displays SSR Design, From Concept to Reality.

Styling, one of the most significant points on the Chevy SSR's journey from concept to reality, is complete. The production-intent design for the Chevy SSR mirrors the theme set forth by the concept vehicle – a celebration of Chevy heritage, expressed in a roadster featuring pickup truck-style versatility.

Quintessentially American, uniquely nostalgic, yet contemporary and innovative, the Chevy SSR concept vehicle made an immediate impact upon its debut in January of 2000. There was little debate on its design. The SSR instantly registered as one of the most stirring concept vehicles in recent memory. Thoughts quickly shifted to "will it go into production, and if so, will it be true to the concept?" The answer to both questions is a resounding "yes."

"From the start, the design team has had a singular focus to be true to the concept," says Bill Davis, Vehicle Chief Designer. "The production-intent show vehicle is the visual essence of the vehicle that will go into production. And, believe it or not, there were some design changes made from the concept vehicle, but they were done in a way that maintained – or even improved – on the concept."

"Our team's mission is simple: Build the concept vehicle," says Tom Wallace, Vehicle Line Executive for GM Midsize Trucks. "Just as they did in inventing the original concept, the design team has hit the mark. We said we would deliver the concept vehicle, and the production-intent show vehicle does just that."

Exterior Styling Enhances Bold Forms

The exterior of the production-intent design embodies the concept vehicle. Only subtle changes have been made from concept to reality. Unlike many show vehicles that proceed to showrooms, the changes represent tweaks meant to improve the vehicle's form, rather than production-necessitated compromises.

The Art Deco styled front grille design – one of the signature features of the concept – continues virtually unaltered in production. Indeed, horizontal cross-car bar with the integrated bowtie continues all the way through the headlamps, just as it does on the concept.

To ensure excellent handling, ride and structural strength, GM's midsize truck architecture was selected to provide the basis for production version. As a result, the proportions of the SSR needed to be altered, providing a challenge for designers. The production-intent vehicle has the same wheelbase as the concept, but is slightly longer and wider.

These subtle dimensional adaptations were achieved without disturbing the vehicle's overall form. For instance, the windshield was pulled slightly forward, and tiny alterations were made to the A-pillar and roof surfaces to maintain the "fast" forward leaning, rear accented vehicle form.

Critical to the vehicle's overall look, the tire-to-body relationship was untouched from the concept with huge 19 and 20-inch wheels in the front and rear, respectively.

The great majority of body panels are stamped steel, including the large fenders. The fenders are identical to the concept, with the exception of the addition of side marker lights added for safety.

The fenders are the boldest expression yet of the "vortex" rear-accented shape that is a key Chevy brand character cue. The large flares date back to the SSR's thematic inspiration, the Advance Design Chevy pickups of the late-1940s and early-1950s.

Concept Reveals Opportunities

Other ideas for the production-intent styling were derived from the team's experience with the concept vehicle.

"One of the great benefits of concept vehicles is that we see other dimensions to it that might not be evident on a computer screen or in the studio," says Davis. "For the production design we had the opportunity to approach SSR as one solid shape rather than a separate cab and box. The tonneau, deck lid and body sides are more of a complete unit in the production-intent vehicle."

More examples of contemporary and roadster cues are found in the interior. The production-intent SSR features sleek, rounded bucket seats, as opposed to the traditional bench found in the concept. This allows the incorporation of a useful center console that provides storage space and a home for the shifter.

"The interior is uncluttered, inviting and sophisticated," says Davis. "The body color flows into the interior in several areas, such as the waterfall between the seats, the doors, rear deck and windshield."

The interior theme is Chevrolet's twin cockpit approach, with a horizontal cross-car bar and body-colored accents bringing much of the vehicle's exterior theme to the interior. The billet aluminum look used on elements of the exterior continues on the door trim and instrument panel bezels. The clean instrument panel features gauges with bold graphics, audio controls hidden behind a moveable panel and a simple three-dial design for all climate controls.

Initial production of the Chevy SSR will begin in late-2002, with regular production to follow in early-2003. Availability will be limited.