I was reading some SAE papers on the development of the C5, and paying close attention to how they acheived the desired weight reduction. There is some pretty clever engineering involved. But what caught my attention was something that they also mentioned in ACAR. The set goal was one reduction in test weight class from the C4. That amounted to 125 lbs at the time. Dropping into a different test weight class does a lot to justify the cost of the weight reduction, so it makes sense that dropping one more class would be a likely weight target for the C6. Unfortunately I can't find any info on exactly what the classes are (numerically). Anyone know. It might give us a better idea of what they are aiming for in terms of weight.

Scott

 

Ive never heard of "test weight class," what is that for? emissions requirements or safety standards? :confused:

 

It's for emissions/fuel economy testing, if I'm not mistaken. It's been a while since I read ACAR, which had a detailed description of what it's for. I don't have a copy here, so I can't check. I haven't found any info online yet.

Scott

 

I read ACAR also and now I know why GM used plastic pieces. I honestly can't see how they can make it any lighter without making it cost more.

 

I don't know the actual cutoff points for EPA test weight classes, but the important parameter is the 125 lb. increment. Also, the weight is based on GVW, not curb weight. The test weight determines the load on the dyno, so the lower the weight, the lower the load, which means less fuel consumed and lower emissions.

It's good that you have read the series of SAE papers - great read! If you read "All Corvettes are Red" your know that Dave Hill watches weight like a hawk - actually, he manages it like an aerospace program - and holds everyone's feet to the fire on weight increases and has incentives to cut weight.

The word on the street appears that the C6 will be a bit lighter - up to 300 pounds has been thrown out. I doubt if it will be that much, but I suspect they can get all three models (assuming there will be three distinct body styles) down one EPA weight class. That would put the Z06 curb weight right at about 3000 even.

Most don't understand how tough it is to build a light car. The curb weight of the Z06 is about the same as my SWC. That's quite a feat! Compare the weight of any other high performance coupe, sedan, or sports car to their closest forebear from 40 years ago. None are even withing spitting distance of their ancestor's weight. They're all much heavier.

Duke

 

Weight reduction is about the most expensive performance improvement there is. I do know the C5 has a few parts that could use a diet, since the original MT900 prototype shared alot more Corvette parts than the current cars. The seats, and steering column mounting (large casting) come to mind right away.

 

Make all the glass thinner like the Z06 did, power anything is an option (and that includes windows), manual tranny, carbonfiber engine bay and hood, aluminum frame. I do know that an aluminum frame is out of the question for the C6, but the others might not be so far fetched :)

Of course, the drivers might want to lose a few lbs here and there. Beneficial to both weight of car and health. Also, the freakin' wheels are heavy! :smash:

 

Thanks for the thoughtful feedback guys. Duke you provide great info. You're right about those SAE papers. They are really enlightening. I'm surprised people here haven't discussed them more. As far as options for lightening the C6, I see a few major areas they might consider. First is the frame. The structure (side rails and backbone) of the C5 is steel, and it's possible that they could save a lot of weight by switching some of that over to aluminum. I honestly don't know anything about the possibility of making that backbone out of aluminum. But I have read about a newer hydroforming processes where they extrude aluminum, and then hydroform it. This allows them to vary wall thickness for different portions of the rail. The windshield A pillar is extruded aluminum in the C5, and the varying of wall thickness there saves something a kilogram. Not a huge amount of weight, but if you did that on the whole frame rail (and switched to aluminum) it might be worth it. Its really amazing how diligent they were about weight on the C5. It seems like in most areas, there's very little weight to be saved without going to lighter materials. Oh...whever mentioned the no power windows and stuff....from what i've heard recently, power windows are often lighter than manual, so that's probably not where we'll find our 125 lbs of weight savings. I'd love to see more use of titanium, as it's getting cheaper and more people are working with it these days. One place where I'd like to see some weight savings is in the brakes. Huge cast iron rotors are cool, but they weigh a ton. If they could offer ceramic brakes as an option (like the one's on the porsches) or the aluminum metal matrix composite brakes developed for the lotus elise....we could save a lot of rotating, unsprung weight. Anyway, I'm sure they are working pretty hard on it, and I think Duke is right that we'll probably see something around 3000 lbs. I personally believe it's going to be a hell of a car, given the expected weight, and power levels, and the current performance of the C5


Scott

 

The ceramic composite brake rotors on the $180,000 Porsche 996 GT2 are standard, but a $9,000 option on the " regular" 996 Twin Turbo. Owners are having problems - very noisy and " grinds " when cold, eating pads irregularly, other typical " first generation" teething problems. They were put in production to save 12 lbs per axle of unsprung weight and to prolong rotor life to 200,000 miles - as if any GT2 will ever see more than 30,000 miles in it's lifetime . :lol:


[Modified by usroute66 MKW, 10:44 AM 10/5/2002]

 

Yeah, the price on them is very very high, but one would hope that light weight brake technology is going to become available to conventional sports cars in the next decade. 12 lbs may not seem like much, but it's rotating unsprung weight. Spinning those big cast iron rotors is a huge waste of energy. My hope is that ceramic, Metal matrix composite, or even carbon fiber rotors will be made streetable, and find their way onto a high performance version of the Vette.

Scott

 

Great post! Hopefully we will see carbon fiber and titanium applications on the C6. :cool: :cheers:

 

funny you say that, I asked that. When i went to the porsche section at the Javits center autoshow this year, I asked that same question. It's all good to have ceramic brakes and all but please keep in mind that they cost $20,000 for just one car. I'm sure GM could cut the price down but they would have to start intstalling it in other cars (the caddy's come to mind on this one) for it to become affordable. If you ask me I do not want to pay another $10,00-$20,000 more just for lighter breaks.

Guys I have been reading these forums for a long time (haven't been a member as long) and to be honest it appears that most of us here in the C6 actually believe GM, Chevy, Hill, Lutz, etc... will all disapoint us. In the 50 years of the corvette I can only think of a select few years where the corvette well... really wasn't the corvette. 1984 comes to mind but we can't just look at the power, we have to look at the car all around. The 1984 corvette was the greatest handling corvette ever (for it's time) it might not have had the 300hp we were looking for but it did handle better then any other corvette.

We have to keep our hopes up and stop saying the C6 will look like this or like that and then post a :U and say your not going to buy a corvette. We can be assured the corvette will be a big leap from the C5. It will handle much better, it will be more powerful then the Z06, it will look amazing (debatable), the corvette pride will live on. The american icon is not about to change for the worse but for the better. We are long gone from the gas crisis and the pressures from the goverment and insurance companies to stop producing powerful cars. GM, Ford, Mopar are all just getting back on track. The late 70's was hell for all us fans, the 80's were painful for us car fans, but the mid 90's we were getting back into that muscle era. We have tons and tons of american build cars coming. GM is revamping the caddy to compete with BMW, Mercedes, Audi, Lexus. American car companies are creating more power and cheaper cars then ever.

The years 2004/5 will be very big for all of us. We are getting more and more cars into the 300hp range, do you not think car companies see this? Do you think GM will honestly let the american icon slip away? Of course not, this is the flagship of GM and most importantly the flagship of the US of A. Chevy will not fail, they will suprise us beyond anything we imaged. The new corvette will be a better corvette, it will accelerate to 60 faster then any corvette, it will have a higher top speed then the ZR-1 it will outhandle the Z06 it will be better, it will be faster and we will like it.

Some guy on the forums once said:


"Corvette character is not about to change. It will always have more power, better handling, more room, and more road presence than anything in its price range. It will always be within reach of many. It will always compete with or exceed the performance level of exotic cars costing two and three times as much.

And a certain number of Corvette owners will complain that it's not good enough."

I think this person sums it up best. I never saved his name so I can't say who said it, but he did say it best. GM will not dissapoint us.

Were we disapointed with the late year C4's? Did GM disapoint us with the ZR-1? God No. Did we not love the LT4? We sure as hell did. Did we love the C5 when it first came out? You bet ya we did. Did we drool over the Z06 perfomance? We make ferrari owners look they got ripped off. Is GM going to disapoint us with the C6? Of course no and we need to stop saying that.

When we look at the time each corvette was made, we come to several conclusions.

1) no corvette is ugly
2) all corvettes are fast
3) we all want one

sure corvettes had their off years, but so does every car. Can you find any other car that has lasted for more then 50 years? I can't think of many. GM in the 50 years it has made the corvette has sold every single one. They sold every ZR-1, they sold every C1 through C5. They have no plans on stopping anytime soon.

Rest assured we will all stay up the night before the offical pictures come out excited as 7 year old children seeing the ice cream truck. We will drop what we are doing and adore, dream of, and wish we can own one of those beauties. GM is not going to fail we can be assured of that.

 

Right on. But I think our perception of the number of eternally disappointed Corvette people is exaggerated, like any other complaint on the forum. There's a few radicals saying the C6 will suck, they won't buy one, it's not enough power, it's ugly, it's a Cadillac clone, but most of us are expectant and hopeful.

I doubt we'll see ceramic brakes on C6 -- at least not from Bowling Green. Aluminum frame? That's the $64,000 question. It could be that the engine bay will house the biggest news with incremental improvements in power and efficiency. That would be enough for me. Better is better.

BTW, here's a link to that quote. http://forums.corvetteforum.com/zero...841429#1841429

.Some guy on the forums

 

:cheers: for finding that link, you name did kind of look familar :cheers:

 

The brakes are an 8000 dollar option on the porsche. I don't know what the cost to the manufacturer is, but I doubt they could be selling them that much below cost. I could imagine the price of those comming down to the point where GM could make them an option on the corvette (say 1500....people paid that much for advanced options like active handling and active damping). And as mentioned above there is the metal matrix composite option (as light as ceramic) and maybe someday carbon fiber).

Now, brainstorming for further weight reduction:

Dual pane windows: Contrary to one's intuition, they are lighter (about 10 percent) than stock, because they are the same thickness. They use two thin panes and a laminate. Since the laminate is lighter than glass, they end up being lighter, stronger (takes about two minutes to break into a car with these) and block a lot of sound. I spent a lot of time corresponding with the engineers at Solutia (they make the dual pane glass for BMW Merc, Audi, et. al) when I was doing my soundproofing project on my caddy, and that's what I learned. On a big hatchback like the coupe, this wieght savings could be usefull, and it would improve customer satisfaction, and safety at the same time. Dodge put this glass on Stratuses sold in Mexico (for security purposes) so it's obviously not prohibitively expensive for the vette.

Carbon fiber on the body: We all know that insurance companies want low repair costs. So we are not likely to see carbon fiber on parts that are hit often....bumbers, hood, quarter panels... So in my opinion, the best bet would be roof, trunk lid, and possibly some internal parts (much of the door structure, and the internal body structure is fiberglass). Since these parts are less likely to get hit, they are a better bet. Also, since internal parts carry some loads, using carbon fiber there may have more gain.

Aluminum frame structure: (discussed above)

Forged suspension components: Not sure how much this could save. The front upper control arms are currently forged. The rest of the components are a hybrid cast/forged process that isn't quite as strong, but is better than a simple casting. Some weight reduction could be seen here.

Titanium exhaust on all models: It worked great on the Z06, I wouldn't be surprised to see it on the rest of the cars

Increased use of high strength steels: Steel has come a long way in recent years, and even those parts which remain steel in the next corvette (rather than going to aluminum) may be significantly lighter. The following is an excerpt from an article on the SAE website Since the C5 was largely engineered in the late 80's and early 90s (I don't recall exactly, but components like the frame, and suspension were pretty much locked down (comparison studies were over) by 1993 or so I think) then it stands to reason that the C5 did not benefit from these developments. It's possible that premium steel alloys could significantly lighten the C6.

Interior weight savings: Many components in the interior of a car can be subjected to weight savings measures. Everything from the components we touch (seats and frames, steering wheel and column, shifter, etc) to the structures that support them. Even components like the radio, gauges, and other electronics can often be made smaller and lighter. I imagine these sorts of things do not escape the attention of Dave Hill who seems second only to Colin Chapman when it comes to weight concerns (he's skinny too...must be a fanatic!:)) I would imagine seeing lighter interior trim materials (but still higher in perceived quality) lighter internal support structures. Lighter electronic components, etc etc. When reading about weight savings on the C5, they went after all sorts of little details....The bar pins on the control arms went to aluminum. The liners for the bushings. Things like that. I imagine they will be examining all the small parts to see if they could benefit from re-design or use of premium materials. Various pieces of hardware (hinges, brackets, latches etc. can probably be lightened and may switch in some cases to light materials.

Tires: The runflats were succesful to a degree, but the added weight (rotational and unsprung) combined with the weak performance characteristics of the tire are not good. I wouldn't be surprised to see them offer a delete option on them and provide an inflator kit like that on the Z06, or switch to a more effective system (the Michelin PAX system is getting to be popular. Perhaps goodyear will be working with them to improve the current system.

That's about all I can come up with at the moment. If anyone else has ideas, throw them into the ring.

Scott


[Modified by LymanSS, 2:49 PM 10/6/2002]

 

IMO,I say we may get Forged Internals & about a 50 lb. weight lose, 20 of that unsprung weight.I believe they will take weight out of the Rotors & hubs and the wheels & a little out of the seats. They may even start back (good idea ) with their Factory Delete Policy of the Good ol Days. And as for Options? I want to see a factory Goodwrench Supercharger Option. :jester I am Optimistic, Cecil


[Modified by Lefty, 5:42 AM 10/8/2002]

 

I heard they are making the C6 about a foot shorter.

 

A little off topic, but could you expand on that? Where did you hear that?

LymanSS, that last post of yours was a terrific read. Thanks for the info. :cheers:

 

I still don't think there'll be a large weight loss regardless. We're not going to see a 2800lb C6, and I think 2900lb is stretching it.

Look at the new Viper Competition Coupe. Its a track-only car with a single seat, racing frame, bare-bones interior, lack of emissions equipment, no interior anemities, carbon fiber body panels,

And it comes-in at about 2900lbs. While GM may be about to shave off 200lbs off the stock C5 weight. We also know that Aluminum is extremely pointless as a frame material. Its nowhere near stiff enough to afford much in the way of weight savings, while at the same time kicking the price of the car up.

 

"I doubt we'll see ceramic brakes on C6" I think you'll see them along with 2 piston calipers on the front. 400HP on the Vert and Coupe and 450HP on the first year Z06 is also a good bet. Weight? should help that the over all size of the car being smaller. Longer and wider wheel base but shorter over all is what I've ben told. Z06 vs. Coupe and Vert, the Z06 will look different with an air-06 package and wider rear then the other Corvettes.
JMO