C6's Hydra-matic, 4L65-E, electronically-controlled, four-speed automatic is a beefed-up version of the 4L60-E, used from 1993 to 2004. The "L65" uses the same gear ratios but has a higher input torque rating of 380 lbs/ft. Its key new features are: 1) planetary gearsets with five rather than four pinion gears. Spreading the load over five pinions increases torque capacity; 2) the stator shaft splines, which engage the stator roller clutch, are now heat-treated; 3) the turbine shaft, which transfers torque from the converter to the input planetary, is now induction-hardened; 4) stronger low/reverse roller clutch assembly; 5) seven plates in the 3-4 clutch rather than six; 6) shotpeened output shaft and 7) a revised valve body.
The L65 uses a separate transmission controller. Transmission control was taken out of the ECM so transmission controls evolution could stay in lockstep with transmission hardware changes. This controller has "Performance Algorithm Shifting" technology which tries to anticipate what the driver is doing with the car in a performance driving environment then alters the shift schedule accordingly. With the L65's input torque rating 20-lbs/ft. less than what the engine makes; the LS2's ECM applies torque management to the engine when the trans shifts at high load and high rpm.
The T56 six-speed manual is upgraded. The shift lever is 3/4-in. shorter. Inside the transmission, the synchronizers were modified with less travel. The combination of a shorter lever and less synchro travel reduced shift throw by 10%.
Shortening the lever increased shift effort. To bring it back down and refine it; GM and TREMEC (the transmission supplier) modified the synchro sleeve tooth configuration; switched to a roller, fore-aft detent and a ball-bearing, cross-car detent and changed from bushings to linear bearings on the main shift rail. Individually, these updates don't have a great effect, but together; they make a noticeable improvement in feel.
First time you drive a C6 manual, you'll notice the shorter throw and the more precise feel. When measured, shift effort goes up 3% but that's virtually impossible to feel. Judged subjectively, I think the effort seems the same as that of my '04 Z06.
With C6's shifter and transmission improvements, the need for aftermarket shifters may have been eliminated, except for hardcore racers wanting an extremely short throw and who will take high effort and close-gated gear selection in return and "mod-freaks" who need to change things, regardless of need.
Because they are intended for severe duty, Z51 six-speeds have a cooling system. A pump on the front of the trans, driven by the countershaft, sends lubricant through the same cooler in the radiator used by automatics.
Finally, there are changes in the rear axle. Besides the revised limited-slip preload discussed earlier, all Corvettes get the shotpeened ring-and-pinion previously used only on manuals.
Bet you didn't know the C6 Convertible's optional, power top is made by Porsche. Car Top Systems, Gmbh, a subsidiary of Porsche A.G. which has done work on many of the finest convertibles in the world, developed the electro-hydraulic drop-top. There's one aspect all C6 convertibles we don't get. The top fabric and back glass are manufactured in a way that makes replacing the glass impossible. So, if the glass breaks or the defogger quits working, you're gonna buy a whole new top assembly. What's up with that?
Everyone's heard about C6's keyless entry and engine-start. But what do you do if there's a power failure and you can't get in? You insert the "metal key" (strange to describe it like that, but I guess we'll get used to it) into a lock under the rear license plate to open the hatch. Then, a pull-cable near the left rear wheel well unlatches the driver's door. What happens, if you're trapped inside by a power failure? On the floor, just outboard of each seat is a manual door release lever. Pull it up and the door opens.
Because some C6ers may get into the habit of carrying the key fob but not the metal key, we got to thinking: what if the battery is dead and you don't have your key. If you opted for On-Star, that service's unlock feature will save you. If your C6 is On-Starless, hmmm...good question. The road service and locksmith business' usual tools, "slim-jims" and so forth, won't work, so new solutions will have to be found. For now, don't leave your C6 physical key at home.
Hill on Bob Lutz, the "Blue Devil" and Other Issues.
When he got into a Beta car on the ride-and-handling loop, he drove it very aggressively and demandingly, then pronounced it 'fantastic'.
C5/C6 Registry: In terms of engineering, what are Mr. Lutz's desires for the future of the Corvette?
DH: I think he wants us to grow our technical superiority over the rivals, to be better than Porsche when it comes high-speed handling and performance. I think, when it comes to the Z06, he wants us to be better than Viper for overall performance. Bob has been a very strong force–and Brent Dewar
(Chevrolet General Manager) is another very strong force–in using the Corvette glow to cast a brighter image on the rest of the GM products. Corvette being the flagship of the American Revolution is workin' really neat.
C5/C6 Registry: That's a pretty cool ad campaign
DH: Yep. It is. Brent is so enthusiastic about the Corvette. Jim Perkins (famed Chevrolet General Manager of the mid-90s) was that way and it's been a long time since Jim Perkins, so I'm so delighted to be bringin' this car to market with Brent Dewar as General Manager. He's a real Corvette fan. He went to the first race for the C5-Rs this year at Sebring and, 12-hours later, he was there cheerin' them on at the finish, so he's our kind of a Chevy General Manager.
C5/C6 Registry: the mythical "Blue Devil–is there a market for an expensive, ultrahigh performance, super-Vette."?
DH: Most important to us is a successful core business–Coupe, Convertible and Z06. Right now, we're not diverting much attention away from that core business.
We are doing some spreading because we've improved the coupe's affordability. The Z51 offers almost-Z06 ride-and-handling for a very affordable price. We are spreading the coupe and convertible farther than they were spread before.
When we get to the Z06, it's gonna have more performance and more appearance differentiation. It's gonna be more expensive, admittedly, but it's gonna be a terrific value in comparison to anything else, including Porsche Turbo, Viper and the Ford GT. By 2006, when you look all the way from a entry-coupe to a Z06, we are definitely offering a broad range of cars.
|
 |
|
Dreamin' and Scheming' is what Hill says he and his folks are always doing but he adds that his core business is not "Super-Vettes". "That core business is Coupe, Convertible and Z06. Right now, we're not diverting much attention away from that core business," The VLE
states flatly. Image: Author |
|
A fourth model is a twinkle in our eye. We never stop dreamin' and schemin,' so we're studying some things, but it really would be foolish to move into the stratosphere. When you look at cars priced between a hundred-and-fifty and four hundred thousand, there's a lot of cars chasin' relatively few multimillionaires. It would be foolish to endanger the Corvette marque by making a car there, so we're schemin'; but we don't have any approval to do anything.
C5/C6 Registry: Do you think an appropriate price of the next Z06 is about that of the old ZR-1 , anywhere from fifty-nine to sixty-eight thousand, depending on model year? |
DH:
Well, I'm not gonna talk about the Z06 price because it's anything but finalized. I think the ZR-1 program had a debatable outcome because it was a lot of money and many elements of the car were not appropriate for the price bein' charged. Consequently, it had a rush of following, but didn't have lasting value. I think we learned a few lessons, there. I don't want to knock the ZR-1s. They were fantastic Corvettes but...
C5/C6 Registry: They were in their day.
DH: Yeah, they were, ah–but I'm not going to say anything about Z06 pricing until North American Auto Show and that's at the earliest.
C5/C6 Registry: What were the goals of the C6 Development?
David Hill: First: Have the very best car in the segment regardless of price.
Second: To annihilate the compromises previously necessary–the little tradeoffs you have to do to have a performance car–and that includes things we were previously satisfied with such as: a car with fantastic tires and suspension that is gonna have road noise.
Three: Exceed expectations of present owners but, also, be able to capture new owners. When I say, 'new owners,' I don't mean just people who are driving an import, but young people who may buy a fine car sometime in the future. We want to appeal more to people who own imports, today, and more to youth, but–we don't want to do anything bad for our present owners.
Four: Be able to offer more car per dollar and to drive our entry price down lower, to be even more competitive with the Nissans and the Mazdas of the world.
C5/C6 Registry: What were the two most significant engineering challenges of the C6 program.
DH:
One was to add performance, comfort, quality and features while, at the same time, reducing mass. Now, we didn't reduce the mass a whole lot because, where we got reductions, we spent them, again, on making other things better. For example, we got rid of the AIR pump but we spent that mass on trunk acoustics. So the challenge was making all these things better but not making the car heavier.
The other was helping styling get all the "wows" they wanted and marketing get all the features that they wanted, while at the same time getting better quality reliability and performance. There's a lot of things in the C6 (bodywork) which are more difficult to manufacture than the C5. Those dips, lines, peaks and bulges–they go across one panel to the next and they make the car sensational. They're challenging to the body engineering and manufacturing folks but we said, 'Hey, we gotta do it because this car is so fantastic looking.'
So the first was getting everything we wanted and reducing mass. The second is getting all the design wows while improving quality and performance.
C5/C6 Registry: Was there a significant feature you wanted for C6 that did not make production?
DH:
We went out to annihilate every dissatisfier. We had a list of things that were possible dissatisfiers, even after perfecting C5 for eight years. We really waxed that list. I'm not gonna share that list with ya, that's our list but, um...getting rid gear rattle, entirely, was on it.
There's three different types of gear rattle, neutral, shutdown and driveaway. We had some hardware that was gonna get rid of all three but and we decided to reverse one of 'em, because the solution was costing too much acceleration. That was a dual-mass clutch and it would have eliminated all of the driveaway rattle but it woulda cost us 2/10ths sec. in 0-60. We said, 'Even for driveaway gear rattle, that's too much of a performance price to pay 'cause it was a significant amount of what we gained with the 400hp.' So we eliminated the neutral gear rattle, the shutdown gear rattle and got more than half of the driveaway gear rattle. That is the only thing that I wanted to get that I didn't.
C5/C6 Registry: When you learned Design Staff was considering fixed headlamps, what was your take on the idea?
DH:
Design was very much for new headlamps because they wanted: a racecar cue, to be new and modern, to distance the car from the Corvettes of the 20th Century and to put more of a face on the car.
Back when they covered up the lights, headlamps were so generic–every car had the same two or four (round light) design. Today headlamps are a style element and (designers) like that style element because it enables them to put beauty into the car.
Engineering wanted very competitive lighting performance which ya oughta have in a car that can go fast. We wanted to be able to package high-intensity discharge lamps which are longer than sealed beams and halogens. At the same time, we wanted to reduce the front overhang which took away packaging space needed for long projector lamps (when retracted). This all precluded these lamps being in a moveable device.
We, also, wanted to reduce mass, improve reliability, and improve the quality appearance because, with the pop-ups, we had a lot of fussy parts to fit and have the gaps be perfect under today's standards.
There were definitely marketing and Chevrolet concerns about breaking with the winning tradition. When the decision was to made, the split was about equal with half of the organization feeling it was a definite wrong thing to do and the other half thinking it was definite right thing to do; so the VLE (Hill himself) made the call.
I give the organization credit because, once that call was made, everybody got on-board and worked to make it the best possible headlamp design. We tried a number of things that were distinctly different than the old pop-ups, before we settled on what we have.
C5/C6 Registry: What was your initial reaction before the different parties stated their cases?
DH: I was an advocate for the engineering side just because of the technology and being able to breakout from constraints which we had before.
C5/C6 Registry: With everybody split 50/50, what was the thing that pushed you over the fence?
DH: My tiebreaker on Corvette is always: when it's technically better for performance, it's the way to go.
C5/C6 Registry: What was your initial reaction to Design Staff's incorporation of significant elements of C2's shape into the C6?
|
|
 |
|
Hill discusses the C6's new headlights at the media briefing on June 4th.
"I was an advocate for the engineering side just because of the technology,"
he told the CAC. Image: Author. |
|
DH:
I despise retro.
I think retro designs show you've run out of ideas, however, I do strongly support showing respect for your history and your lineage, especially if you're a proud marque, but–you gotta do it in a way that's not overstated.
Some of the Stingray elements were dysfunctional and I opposed those. Other Stingray elements are very dramatic, distinctive and ownable as a Corvette cue and I supported those.
I think everybody worked hand-in-hand to achieve these cues from our heritage but make them modern and appropriate for a 21st. Century automobile. Engineering had to work hard to support what Design wanted because it's very difficult to shorten the car, make the aero better and make it crash (test) better. Design worked really hard to avoid the dysfunctional elements of the Stingray design–you know what they were–some had bad aerodynamic lift, terrible visibility and, in the case of the C3, terrible roominess.
I feel we got just the right amount of heritage in an extremely modern design. I think, like the '63-'67, it's so right that it's going to last forever, but unlike the '63-'67; this one's technically right, too.
|
|
|
Hill on the Stingray influence, "I despise retro...however,
I do strongly support showing respect for your history and your lineage."
Image: Author. |
|
C5/C6 Registry: With respect to hybrid powertrains and alternative fuels: where do you see the mid-term and long-term future of Corvette's powertrain heading?
DH:
We wanna meet and exceed the operating cost expectations of our customers. I don't think we have any environmental bandwagon to be on or carry any green banner for General Motors. We have other vehicles which are doing that.
GM is tryin' to do a responsible thing with the big consumers (of fuel) like sports utilities, mass transit and other, heavy vehicles because we're gonna be able to make a greater impact on the global situation with that. In Europe, we're gonna be very progressive with Opel and Saab on diesels, advanced propulsion and hybrids, so Corvette doesn't have to be the green banner carrier for GM.
That said, we do need to exceed our customers' expectations, so if fuel costs go up or if gas guzzler taxes rise, then we're going to put more of our available resources into fuel efficient technologies. We can do that if it becomes necessary, but it is really important to never let the, next Corvette be slower than the last Corvette.
|
When that happens, the value of the brand goes down. We must remember that we're a performance automobile. People love the fact that Corvettes are surprisingly fuel efficient and we're always gonna use aero, great engine design, great transmission design and great tire engineering to keep 'em that way, but we don't want to degrade the performance of the Corvette in any way.
|
There are technologies which could come out of the GM portfolio and be put on the street, like Displacement on Demand, direct injection, multispeed transmissions with flexible shift schedules, so there's a lot of things that we can do, short of goin' to hybrids, and, you know– even hybrids are a possibility, as well, but, uh...we feel we're gonna have a steady following so long as we meet and exceed people's needs for operating expense. We make a very credible, fuel efficient car and we're gonna keep doin' that.
C5/C6 Registry:
With respect to the near term, I heard a few months ago that DoD would not be used on the Corvette due to a noise and vibes issue. Are you still working on DoD or has it been rejected.
DH:
We took it out of the program for 2005 and we're not active with it at this time.
|
|
|
|
Hill is often quoted as saying, "...it
is really important to never let the, next Corvette be slower than the
last Corvette." Looks like he follows through on that by getting
first hand experience, here, in a Z51 at Virginia International Raceway.
Image: Richard Prince. |
|
| |
 |
