Pontiac's Bright Light: Creating The Solstice
Automotive Design & Production - September 15, 2005
Can a single low-volume car help generate levels of enthusiasm for a brand? Apparently, the answer is "YES."
When asked what he thinks the pontiac solstice will do for pontiac, john larson, pontiac division general manager, answers without reservation, "worlds." Before the first car rolled out of the wilmington, de, assembly plant, the division had 9,000 orders. While larson admits that some of those people might not follow through, the level of enthusiasm that he's witnessed for the vehicle (during the press introduction in portland, oregon, one of the "first 1,000" people to place an order for the car spotted a photo on a blog, analyzed the background, determined where the hotel was, and set out to see the cars and to meet people who have been raised to demigod status in that world, like small car vehicle line executive lori queen), he's not concerned that they'll be able to sell what they build. And while he's not specific about the number of vehicles that they'll be building annually in the plant-low-volume production that will be shared with saturn when it comes out with its sky roadster in the first quarter of '06-he provides a ballpark of 15,000 to 20,000 units, but notes that they'll always try to have one less solstice than there is demand for, a strategy that was used by mazda for its miata two-seater . . .Speaking of which, larson points out that the 9,000 orders is nearly the number of miatas sold last year (9,356). While there was some pre-production public speculation that the program was being delayed, larson points out that they'd always promised that the vehicle would be coming in the summer of '05, and that the first 1,000* went out the first week of august. "We're on the cusp of great things at pontiac."
Why you can't always believe even accurate reports about production problems being, well, problems.
About those widely reported hiccoughs for the solstice, the problems with the front fascia, the top, etc. Lori queen explains that if the solstice had been a high-volume, high-risk vehicle (like, say, the chevrolet cobalt, a program that she was working on at the same time as the solstice), then those problems would have been, well, problematic. But in the case of the solstice, this was a matter of expectation, not enormous concern. That is, the development of the program was one where they went from the math data to production tools. There were no intermediate prototype tools-or vehicles built (so-called "integration vehicles")as would be the norm in a vehicle program. Part of this was an issue of cost, as this was to be not only a low-volume program, but a low-cost program, as well, with the car starting at less than $20,000 ("ten years ago, a vehicle with fewer than 30,000 units would be a premium program," queen remarks). And it was a matter of timing, too (it was a 27month program), and tooling builds take plenty of time. "We pulled tools ahead and assumed that there would be fit or processing problems," queen says, which is certainly a non-traditional approach to vehicle development. In fact, the entire program-which she not entirely facetiously describes as "no volume, no money, no time"-was one where non-traditional approaches were the norm, not the exception. Normally, she explains, there would be three iterations:
• integration vehicles
• production tools
this was not so with solstice. ("Boeing doesn't double tools," she remarks of how the aircraft manufacturer develops new products.) "We pulled the tools ahead and assumed that there would be fit or processing problems," queen says. That's why there were those reports of problems. It may have surprised some people, but not the solstice development team.
While the present mantra at cm (as well as all vehicle manufacturers) is about the importance of math modeling and about "going straight to math," queen (who is not only an engineer, but whose husband, ]im queen, is gm's vice president, global engineering, so she knows more than a little something about engineers), points out, "if engineers think they have another chance, they don't take the math seriously." In other words, if it is known that there will be another opportunity to make a change to something as the program goes through another stage (e.G., Pre-prototype to integration vehicles), then there is a tendency to figure that they'll get it right at the next step. "Engineers triage what to do everyday," she remarks. So what's key is getting things done. But faced with the fact of going to production tools, the opportunity for putting things off simply isn't there. She acknowledges that during the development they made some people uncomfortable as they followed a course that took the traditional critical path approach and threw it out the window.
What they've done is to create a new approach. It is one that she says can be used for other programs going forward. The aforementioned problems were anticipated-not necessarily the precise problems, but that there would be problems was expected. It was a matter of building, testing, then tweaking until they got it right. Certainly, given that they were working on a low-volume program-queen says that it is exceedingly unlikely that they'd ever take this approach fora cobalt-like program, where you're betting the store on success-and that because they were starting with a clean-sheet (i.E., Developing the kappa architecture, so it wasn't a matter of trying to modify things that existed), the solstice program methodology is in the cm book of how to do things better, faster and cheaper.
When's the last time you read about a car being produced by a mainstream brand and "robotic: welding" isn't part of the story?
Structurally, observes bob lutz, the solstice platform is like a "reduced corvette," as there are two hydroforrned frame rails running fore and aft. The cross-car beams are attached to those rails with mig welding. Given the lowvolume production volume of the vehicle, there is no robotic welding in the plant: all of the welding is performed by hand. Given that are welding is a considerable skill and that most automotive welding is robotic resistance welding, extensive training was performed at wilmington to get personnel there ready to weld what is arguably a hand-built car. Even though it was conceived and designed as a convertible, this arrangement makes the vehicle rock solid: it has a bending " frequency of 20.9 Hz and a torsional frequency of 18.8 Hz.
Remembrances of things past.
When pontiac produced the fiero back in 1984, it was relatively revolutionary so far as north american vehicles went in that it wasn't a unibody nor was it a body-onframe (at least in a conventional sense). Rather, the fiero consisted of machined and then assembled structural elements that formed a "bird cage." Nonstructural polymer panels were then attached to it. In the case of the solstice, the body panels are nonstructural; there isn't a cage per se-for one thing, there isn't a solid roof. But like the fiero, the structure isn't dependent on the panels. Lori queen said that one result of this was that they were able to produce 12 structural mules during development to help correlate with the analysis models that were created in math. "You don't need pretty sheet metal to do that," she says.
Why working, in public (sort, anyway) can have benefits during development. Not huge ones, but benefits nonetheless.
One of the benefits of revealing the concept solstice (designed by franz von holzhausen; driven out on a stage by bob lutz) at the 2002 north american international auto show in front of the world, then staying true to the car as styled was that during the development process they didn't need to worry about camouflaging the car or having spy photos taken during the development. They showed the car, received tremendous accolades and interest, and then they announced that it would be produced. But there was a nontrivial issue: what platform would they build it on? They didn't have a small rearwheel-drive platform. Queen says that they looked at sigma (which is used for the cadillac cts), but it was too big. They considered using the front-drive delta platform (e.G., Saturn ion) and running a transmission tunnel down the center, but that proved to be too unwieldy. She says they spent more than six months working on the determination of what they would do. And they settled on creating kappa.
The cs corvette brought tubular hydroforming to the fore. The soltice will probably do the same for the sheet-forming process.
The deep-drawn forms that make up the major elements of the solstice body are not stamped. In fact, there's only one exterior panel that's stamped, which is a small panel between the front wheel well and door edge. Queen suggests that given the depth of some of the draws on the hood, for example, stamping is out of the question. This is a steel body. Even a progressive die set would be hard pressed to achieve those curves. The process that is being done is sheet hydroforming, also known as hydromechanical deep drawing. General motors metal fabricating div. (Mfd) worked with amino corp. Of fujinomiya, japan, which has opened operations in st. Thomas, ontario, on this process that is ordinarily used for short-run operations. Amino corp. Has done extensive development on the hydroforming process; mfd has high competence in both simulation and production. Essentially, this is an operation where there is a pressurized water chamber into which a punch pushes the metal blank. The water in the tank performs as the female die in this setup. Since there is one hard tool, this is more cost-effective than a complete dieset. However, it is a far more time-consuming process, so its applicability, queen observes, is pretty much limited to lower volume vehicles (~20,000) like the solstice. (She is also working on the next kappa-based roadster, the saturn sky. The sky has sharp creases on its clamshell hood over the wheels [i.E., Forming the fenders] in addition to the deep draws, so the sheet hydroforming is essential.)
Oh yeah. The car...
So what about the vehicle? "There's not a car out there with these proportions," claims doug parks, chief engineer on the program, who adds that it is a "dead-on ringer for the show car." The roadster's design features a long hood, short overhangs at the front and rear, a high belt line, clean sides, wide 18-in. Wheels and tires out at the corners, and more curves than anything this side of the rockettes. The overall length is 157.2 In.; The wheelbase is 95.1 In.; The width is 71.3 In. And the height 50.1 In. The curb weight is 2,860 ib. Under the clamshell hood is a 2.4-Liter ecotec four-cylinder engine that provides 177 hp @ 6,600 rpm and 166 ib.-Ft. Of torque @ 4,800 rpm. So if you do the math, the vehicle has a weight-to-horsepower ratio of about 16.2 To 1. The engine has dual overhead cams, continuously variable intake and exhaust valve timing, polymer coating on the pistons, and other features that provide performance for the vehicle. Hydraulic engine mounts are used to smooth engine feel. The engine is mated (there is a full-circle transmission mount on the engine, so there's solid mating here) to an aisin five-speed manual that features a short-throw shifter. (A hydramatic 5l40-e automatic transmission will be on its way later in the '06 model year.) The rear axle is derived from the cadillac cts.
The vehicle has a four-wheel independent suspension system. There are forged aluminum upper and lower control arms. Bilstein coil-over monotube shocks are used all around. The disc brakes have 11.7-In. Rotors in the front and 10.9 In. Rotors in the rear. The tires used are p245/45r 18-all season tires, or, more simply put, tires that put a whole lot of rubber on the road of a car of the size of the solstice. In fact, given the base msrp of $19,995, it's a whole lot of car, limited in volume though it may be.
* As part of a promotion with the donald trump tv vehicle, "the apprentice," pontiac created an early-order program that combined an on-line element and a visit to a dealership. They figured that the 10-day program would net 1,000 orders. Remember: the car was not out. People couldn't kick the tires and slam the doors. As things turned out, 1,000 cars were sold in 41 minutes, probably something worthy of a guinness book of world records slot. These first 1,000 owners will have their cars marked with a special insignia on the dash and a sequential vin number. By the end of the promotional program, they'd sold 7,116 cars.