by Hib Halverson
Imagery by GM Communications, Richard Prince, U.S. Air Force and Sharkcom
©2005 Shark Communications
No use without permission
We've spent a lot of time on the C6 Corvette's meat and potatoes, the powertrain and chassis, but there are some other features we need to cover. Obvious is the new, power-operated top option on the Corvette Convertible.
We're not sure why a car with a top stack that is so light to begin with needs a powered mechanism costing two grand (the car's most expensive option), but GM apparently had enough customer interest in it during the C5 era so, it was added to the new car. It works with a latch and a button, takes about 20 seconds to deploy or retract and adds 14 lbs. to the car. The power top occupies no more space than the manual version.
In both its manual and power versions, the soft top is made with five layers of a thick, durable insulating fabric called "Twillfast" and is available in three colors: black, beige and gray. In its retracted position, it has a more smooth and contoured appearance which better conceals its structure than did the previous top. This, also, helps minimize the top's negative impact on the car's aerodynamics.
The top stack was designed and is manufactured by a subsidiary of Porsche, A.G., Car Top Systems, Gmbh, a company which has done work on many of the finest convertibles in the world. "CTS" built a production facility in Bowling Green, Kentucky to supply the plant which builds the Vette and the Cadillac XLR.
In addition to the new power top, other improvements make all Convertibles more pleasing to drive, especially on long trips. A bulkhead has been added between the seats to: reduce noise coming from the trunk/top compartment, better contain items in the trunk and enable the addition of a storage area behind each seat. The manual top mechanism was redesigned with a weight savings of 8.6 pounds. Rear visibility improves with glass 18.5% larger and, like C5, the backlight has a standard defogger.
C6's windshield frame was designed using computer analysis to model airflow in the interest of improving topdown quietness, especially in the frequency range of conversation. That seems to have worked because not only is it somewhat easier to chitchat during topdown driving, but wind buffeting has been reduced, too.
As part of GM's noise-reduction efforts, "indexing" side glass was added to all C6es. The door modules detect the top position of the glass and calculate the actual window position. The side glass is in zero position when the window is closed but whenever a door is opened; the window "indexes" to a slightly lower position. This ensures the window snugs up against the weatherstrip for a positive seal after the door is closed.
Another feature revised for the C6 was the head-up display (HUD). We talked briefly about this in the Corvette Action Center's first C6 story (see: C6, Naked and Exposed: Corvette Action Center's First Look at the 2005 Corvette) and, now, we have more details.
The 2005 HUD has a more crisp look because the previous, fixed bar elements used to display data have been replaced with LCD pixels. Using pixels, also, allows the display to change shape and size, which the previous display could not.
Like the '99-'04 HUD, you can "step" though different modes of operation using the "page" button on the left of the IP, but you have more choices in modes. There are three, "Street", "Track 1 and "Track 2". Street mode's standard display data is speed and turn signal indicators. Optional are tachometer, high beam indicator, gear selection (auto), upshift indicator (man.), coolant temperature, transmission temperature, oil pressure, engine oil temperature, sound system data and info from the navigation system. These options are available in several different groups, not individually.
Track 1 mode gives you a tach, speed, engine condition gauges and real time lateral acceleration data. Options are a larger tach and various combination of gauges. Track 2 gives you the larger tach, speed, engine condition gauges and the real time lateral acceleration display. Optional are a different layout of the tach and various engine gauges.
In total, between the three modes, there are 10 different HUD display choices.
Right at post-time, I got the notice for the recall campaign GM is running on the electric steering column locks (ECL) on many '97-'04 Corvettes and which needs to be done to my '04 Z06. This recall, along with the first ECL recall GM had, emphasize the fact that the ECL has been a bit of a problem since 1997. I said this earlier and I'll say it again: the C6 uses similar devices to accomplish steering column locking. The Corvette Action Center hopes GM's development of that system was more comprehensive this time. With so much more of the locking, entry and engine start process controlled by electronics or electromechanical devices, another major problem in that area would be devastating.
While I'm a big fan of C6's keyless operation, I'm wondering what an owner does who loses his/her CID and also isn't carrying the physical key required to unlock the rear hatch and gain entry. With no mechanical locking mechanisms in the doors, locksmiths and road service providers are going to have a tough time using their slim-jims in situations like that.
Generally, the C6 interior is well-done but, once again, the HUD controls are hidden by the steering wheel rim. You've got to tilt your head left and look around your left hand to see them. I wish GM would have fixed that. I also wish they could make the shift light a color different from all the others used in the HUD. The C5 shift light was hard to find and so seems C6's.
I was at a dealer the other day looking through some of the advanced service data on C6. In reading the section on the new convertible top, I learned that the top fabric and back glass are manufactured in a way that makes replacing the glass impossible. So, if the back glass gets broken or the rear window defogger quits working, forget about simply replacing the glass. You're going to buy a whole new top assembly. That's an expensive burden on the customer and not very smart.
The C6 fuel filter is inside the left fuel tank. It was moved there during the 2003 model year at about VIN 11,000. The move was forced by the U.S. Environmental Protection Agency's (EPA) continuing pressure on car companies to reduce evaporative fuel emissions and, perhaps, for ease of manufacture. It's hell if the filter has to be replaced due to an unforeseen problem with fuel contamination, such as debris, water in underground gasoline storage tanks or vandalism.
To replace the filter requires pulling the fuel tanks and before you can do that, you have to remove the transaxle and driveline. Now, service technicians will undoubtedly develop methods other than those in the factory service manual to shorten their time on the job, but the fact remains that the "flat rate" time charged for the job will probably include driveline and transaxle removal. As a fuel contamination problem due to outside influences would not be covered under warranty, I'd be damn upset if my C6 had to have a job costing many hundred dollars to change a filter costing a few bucks. That, also, is an expensive burden to the customer and not very smart. You can thank the green-jihadists at EPA for that.
Back in January, in the Corvette Action Center's preliminary C6 coverage, we talked about an apparent disparity between the claims about interior space in GM's press releases and the actual, Society of Automotive Engineers (SAE) standard interior volume measurements listed in the specifications GM has given-out for the car. GM had been saying that the shortening of the car was achieved "...with virtually no loss of usable space." but that claim seemed not to agree with specs it supplied which clearly showed a 2.2 cu. ft. loss in volume.
Later, we found out from GM Spokesperson, Wendy Clark, that "useable space" in "GMese" means "occupant space" not cargo space, storage space or SAE interior volume, so in spite of a shorter car, there's no loss in space used by the people in the car, but there is a slight loss-the 2.2 cu. ft.-in cargo space and in overall interior volume as measured by SAE standards. Get it?
Many Corvette owners like to modify their cars and that won't change with the C6. Ironically, the first hat in the C6 aftermarket ring is the OE manufacturer, General Motors. The Corp's Service Part Operations (SPO) Division, or "Spough," as insiders say, has already introduced a "Genuine Corvette Accessories" brand.
SPO will be early to market with a 10-spoke wheel available with several finishes. Using Corvette Accessories, C6ers will be able to switch body-color parts for standard gray pieces. According to an SPO press release, examples are, the CHMSL/pup-spoiler discussed earlier, license plate holders and "exterior door handles"-an astonishing trick on a car which has no external door handles or locks to begin with.
The Genuine Corvette Accessories program also includes a color-keyed shift knob, shift boot, parking brake handle and p-brake lever boot, along with aluminum sill plates which coordinate with the metal interior accents. There's a storage tray for the coupe and a storage pouch for both the coupe and convertible. A windbreak reduces air turbulence when a Convertible's top is down.
"Such high-level integration with the vehicle ensures harmony between the it and the accessories," Vicki DeGrace, Corvette Accessory Program manager told the Corvette Action Center. "Genuine Corvette Accessories were designed to enhance the appearance and meet customer needs."
"They, also, offer the peace of mind of a GM warranty, either 36 months/36,000 miles on installed parts or 12 months/12,000 miles on over-the-counter sales," DeGrace continued. "The advantages of Genuine Corvette Accessories are clear: most tailored appearance, OEM quality, and the GM warranty."
Ms. DeGrace and SPO have created a potentially potent competitor in some segments of the existing Corvette aftermarket, but has the General caught the competition napping and will it snag a big chunk of market share? Well-established companies like Mid-America, Eckler's or Corvette Central think that might not be the case.
"Right now, GM's line is so limited, it's not going to be a significant factor," Tom Christmann, Marketing Manager for Corvette Central told us. "Exhaust is a good example. Look at the aftermarket, today. For the C5, there has to be 20 different exhausts-every size, shape, sound, exhaust tip. If GM comes up with an exhaust, there will be 15 other variations out there, somewhere, so there's plenty of room for everybody.
"The folks in the aftermarket, today, have done such a good job that GM wants a piece of that aftermarket pie. This just means it's a great healthy, driving market and a new car makes new opportunities.
"The products that will come first are the ones which are the easiest," Christmann continued. "Our staff was just talking about exhaust. We have pictures of the C6 exhaust system. We're discussing what it's going to take to enhance it-put on a different kind of muffler with a different sound, add different tips, maybe. Exhaust always seems to be a hot thing with Corvettes and C6 is not going to be any different."
Christmann didn't address performance increases from exhaust. It is possible that his company and others considering exhaust systems for the '05 may find that the days of significant power increases from "cat-back" systems on Corvettes with stock or near-stock engines are over and, because of that, customer interest is going to be focused on changing sound or appearance.
How does Corvette Central view the profit potential in other C6 parts? "It's an exciting prospect for us," Tom Christmann answered. "The average customer wants to personalize his car. When he or she personalizes it, they go for accessories. Besides exhaust? Well...it's not a part, but it's something most Corvette owners want-a car cover. It's a simple product but demand will build quickly for it.
"Aftermarket wheels are going to be a factor. Engine dress-up is going to be a factor. Just as it was with the C5 market, for C6, we'll have the carbon fiber pieces, painted-body-color kits and all the different chrome items. You're going to need a cargo mat. You're going to need floor mats. You're going to need seat savers or seat covers. Again, all this is to personalize the car, not necessarily to enhance performance.
With C6s still a week or so short of arrival on dealer sales floors, Tom surprised us by saying, "We're also looking at the car, long term. Today, it's a new car and all you're doing is accessories. Five to ten years from now, you're going to be restoring and/or maintaining it. As things wear or break and GM no longer offers them; we're going to be right in the thick of things saying, 'How can we manufacture that. It's breaking on a significant number of cars and we need to come up with a replacement for it because GM doesn't have it anymore?' One new car is longevity and security for the whole aftermarket and that's 5, 10, 15, 20 years from now as well as the initial round of accessory offerings."
While a sizable part of the Corvette aftermarket is focused, at least initially, on personalization rather than performance; the hard core hot-rodder that I am says we need to look at some performance stuff.
While some of the "low-hanging" fruit is gone (IE: C6 exhaust and intake systems are pretty good, whereas modest improvement could be attained with replacement of the same on C5), one place a C6 hot-rodder can gain power is by installing the higher-lift cam and the hollow-stem valves from the '02-'04 LS6. You must add those as a package. You can't just add the cam because its smaller base circle requires the longer, late-LS6 valves. Informed sources at GM told us this change gains about 10hp with stock heads and as much as 15hp if the heads are ported. A camshaft to look at for race-only applications is the the Gen 3 "Showroom Stock" racing cam which GM sells through its Performance Parts program. It has .045-in. more lift and 20o more intake duration than the 2nd-design LS6 cam. It requires different valve springs, the LS6 hollow stem valves and notched pistons. In addition to the Showroom Stock cam, aftermarket cam companies such as Crane and Comp have profiles designed for Gen 3s that will easily go into a Gen 4.
Even more can be gained by changing to the AirFlow Research aftermarket cylinder head for the LS6 which, also, bolts to the LS2. The combination of the AFR head, the LS6 cam and valves and ECM recalibration by an aftermarket calibration specialist such as Z-Industries, should take the LS2 to around 440hp. If you swapped the LS6 cam for the ASA cam in your AFR-head racing engine and get the exhaust back pressure down near zero; you might see 460hp, however, that will come at the expense of some low-end torque and won't pass an emissions test.
Four-into-one, tuned headers, while common on C5s, are going to be almost impossible on street-legal C6s because of the LS2's close-coupled catalytic converters, however, the quasi-legal switch to headers and aftermarket cats might be a ticket to some extra power, provided the user wants to go to the effort and expense.
As they are with C5, superchargers will probably become a popular mod for C6s, but it may take the blower business a while to tool-up the parts because in some cases the superchargers will have to be repackaged to fit in the C6 engine compartment and new hardware may need to be created. Superchargers, even 50-state legal ones like the Magna Charger, can add 30%-50% more power.
From a rear axle standpoint, C6 has not changed much so the axle ratio choices C5ers have from the aftermarket may carry over to C6. An axle ratio change can sometimes make as much of an improvement in acceleration as can significant engine mods.
Obviously, this discussion of C6 aftermarket performance only scratches the surface. Back in late 1997, when the C5 aftermarket was just getting started, no one foresaw the huge success it would attain. With the new, 2005 Corvette, we're sure similar success is in store.