2014 Stingray
01-20-2013, 06:27 PM
#181
Burning Brakes
01-20-2013, 08:12 PM
#182
Race Director
Changing the subject back somewhat: To all of you so-called "armchair engineers" that are criticizing the Corvette's leaf springs (actually a single, transverse composite spring), check out Wikipedias study on this.
Advantages
Less unsprung weight. Coil springs contribute to unsprung weight; the less there is, the more quickly the wheel can respond at a given spring rate.
Less weight. The C4 Corvette's composite front leaf weighed 1/3 as much as the pair of conventional coil springs it would replace. Volvo reported that the single composite leaf spring used in the rear suspension of the 960 Wagon had the same mass as just one of the two springs it replaced.[8]
Weight is positioned lower. Coil springs and the associated chassis hard mounts raise the center of mass of the car.
Superior wear characteristics. The Corvette's composite leaf springs last longer than coils, though in a car as light as the Corvette, the difference is not especially significant. No composite Corvette leaf has ever been replaced due to fatigue failure, though steel leafs from 1963 to 1983 have been. As of 1980, the composite spring was an option on the C3.
As used on the Corvette, ride height can be adjusted by changing the length of the end links connecting the leaf to the suspension arms. This allows small changes in ride height with minimal effects on the spring rate.
Also as used on the C4 front suspension, C5, and C6 Corvettes, the leaf spring acts as an anti-roll bar, allowing for smaller and lighter bars than if the car were equipped with coil springs. As implemented on the C3 and C4 rear suspensions with a rigid central mount, the anti-roll effect does not occur.
Packaging. As used on the C5 and later Corvettes the use of OEM coil over damper springs would have forced the chassis engineers to either vertically raise the shock towers or move them inward. In the rear this would have reduced trunk space. In the front this would have interfered with engine packaging. The use of the leaf spring allowed the spring to be placed out of the way under the chassis and while keeping the diameter of the shock absorber assembly to that of just the damper rather than damper and spring.
Disadvantages
Packaging can be problematic; the leaf must span from one side of the car to the other. This can limit applications where the drivetrain, or another part, is in the way.
Materials expense. Steel coils are commodity items; a single composite leaf spring costs more than two of them.
Design complexity. Composite monoleafs allow for considerable variety in shape, thickness, and materials. They are inherently more expensive to design, particularly in performance applications.
Cost of modification. As a result of specialized design and packaging, changing spring rates often requires a custom unit. Coil springs in various sizes and rates are available inexpensively.
Susceptibility to damage. Engine fluids and exhaust modifications like cat-back removal might weaken or destroy composite springs over time. The leaf spring is more susceptible to heat related damage than conventional steel springs.
Perception. Due to its association with spring-located solid axles, the leaf spring has a stigma unrelated to the spring itself.
Advantages
Less unsprung weight. Coil springs contribute to unsprung weight; the less there is, the more quickly the wheel can respond at a given spring rate.
Less weight. The C4 Corvette's composite front leaf weighed 1/3 as much as the pair of conventional coil springs it would replace. Volvo reported that the single composite leaf spring used in the rear suspension of the 960 Wagon had the same mass as just one of the two springs it replaced.[8]
Weight is positioned lower. Coil springs and the associated chassis hard mounts raise the center of mass of the car.
Superior wear characteristics. The Corvette's composite leaf springs last longer than coils, though in a car as light as the Corvette, the difference is not especially significant. No composite Corvette leaf has ever been replaced due to fatigue failure, though steel leafs from 1963 to 1983 have been. As of 1980, the composite spring was an option on the C3.
As used on the Corvette, ride height can be adjusted by changing the length of the end links connecting the leaf to the suspension arms. This allows small changes in ride height with minimal effects on the spring rate.
Also as used on the C4 front suspension, C5, and C6 Corvettes, the leaf spring acts as an anti-roll bar, allowing for smaller and lighter bars than if the car were equipped with coil springs. As implemented on the C3 and C4 rear suspensions with a rigid central mount, the anti-roll effect does not occur.
Packaging. As used on the C5 and later Corvettes the use of OEM coil over damper springs would have forced the chassis engineers to either vertically raise the shock towers or move them inward. In the rear this would have reduced trunk space. In the front this would have interfered with engine packaging. The use of the leaf spring allowed the spring to be placed out of the way under the chassis and while keeping the diameter of the shock absorber assembly to that of just the damper rather than damper and spring.
Disadvantages
Packaging can be problematic; the leaf must span from one side of the car to the other. This can limit applications where the drivetrain, or another part, is in the way.
Materials expense. Steel coils are commodity items; a single composite leaf spring costs more than two of them.
Design complexity. Composite monoleafs allow for considerable variety in shape, thickness, and materials. They are inherently more expensive to design, particularly in performance applications.
Cost of modification. As a result of specialized design and packaging, changing spring rates often requires a custom unit. Coil springs in various sizes and rates are available inexpensively.
Susceptibility to damage. Engine fluids and exhaust modifications like cat-back removal might weaken or destroy composite springs over time. The leaf spring is more susceptible to heat related damage than conventional steel springs.
Perception. Due to its association with spring-located solid axles, the leaf spring has a stigma unrelated to the spring itself.
01-21-2013, 11:24 AM
#183
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On a Porsche, it would go through the motor. And that's impossible.
I'm not trying, not at all, to argue that a Corvette is better than a Porsche. I have a 991. I haven't had a Corvette since 1996. Since then I've had only Porsches and Ferraris, usually both at the same time.
What I'm saying, is that the leaf spring argument doesn't hold water. It's just another way of showing you're not as smart as the engineers who worked on the suspension.
And now for the "plastic" body panels. They don't dent. They don't rust. They are harder to damage than steel. Dreaded, hidden damage concealed by paint and bondo don't exist. They are not the same fiberglass and bonding strips they were in the 50's and 60's. They are now called sheet molded composite and they have come a long way since both Porsche and Ferrari used fiberglass on certain models in the past to save weight. Carbon fiber, extensively used in the new Corvette, is a dream product reserved for the most expensive Porsches and Ferraris.
I'm not trying, not at all, to argue that a Corvette is better than a Porsche. I have a 991. I haven't had a Corvette since 1996. Since then I've had only Porsches and Ferraris, usually both at the same time.
What I'm saying, is that the leaf spring argument doesn't hold water. It's just another way of showing you're not as smart as the engineers who worked on the suspension.
And now for the "plastic" body panels. They don't dent. They don't rust. They are harder to damage than steel. Dreaded, hidden damage concealed by paint and bondo don't exist. They are not the same fiberglass and bonding strips they were in the 50's and 60's. They are now called sheet molded composite and they have come a long way since both Porsche and Ferrari used fiberglass on certain models in the past to save weight. Carbon fiber, extensively used in the new Corvette, is a dream product reserved for the most expensive Porsches and Ferraris.
01-21-2013, 11:55 AM
#184
Nordschleife Master
We've been beating this subject to death,with interesting opinions on both sides.
To me,it all comes down to the price...I'm very very curious about this : if the new C7 will cost 60K standard,how much do you think the manufacturing cost is and what is GM's profit margin? I'm just guessing here...40K manufacturing cost? That sounds ridiculously low for a sports/performance/high quality automobile...so what's their secret? Cheap labour? Doubt it...we're in USA.
Cheap quality materials...YES! That's the answer!
How about Porsche? What do you think it's their manufacturing cost? On a 911 I believe is high and their biggest profit comes from the options package. Also,as numbers show,Porsche is staying profitable thanks to Cayenne and Panamera,not to the 911.
To me,it all comes down to the price...I'm very very curious about this : if the new C7 will cost 60K standard,how much do you think the manufacturing cost is and what is GM's profit margin? I'm just guessing here...40K manufacturing cost? That sounds ridiculously low for a sports/performance/high quality automobile...so what's their secret? Cheap labour? Doubt it...we're in USA.
Cheap quality materials...YES! That's the answer!
How about Porsche? What do you think it's their manufacturing cost? On a 911 I believe is high and their biggest profit comes from the options package. Also,as numbers show,Porsche is staying profitable thanks to Cayenne and Panamera,not to the 911.
01-21-2013, 12:19 PM
#185
Rennlist Member
We've been beating this subject to death,with interesting opinions on both sides.
To me,it all comes down to the price...I'm very very curious about this : if the new C7 will cost 60K standard,how much do you think the manufacturing cost is and what is GM's profit margin? I'm just guessing here...40K manufacturing cost? That sounds ridiculously low for a sports/performance/high quality automobile...so what's their secret? Cheap labour? Doubt it...we're in USA.
Cheap quality materials...YES! That's the answer!
How about Porsche? What do you think it's their manufacturing cost? On a 911 I believe is high and their biggest profit comes from the options package. Also,as numbers show,Porsche is staying profitable thanks to Cayenne and Panamera,not to the 911.
To me,it all comes down to the price...I'm very very curious about this : if the new C7 will cost 60K standard,how much do you think the manufacturing cost is and what is GM's profit margin? I'm just guessing here...40K manufacturing cost? That sounds ridiculously low for a sports/performance/high quality automobile...so what's their secret? Cheap labour? Doubt it...we're in USA.
Cheap quality materials...YES! That's the answer!
How about Porsche? What do you think it's their manufacturing cost? On a 911 I believe is high and their biggest profit comes from the options package. Also,as numbers show,Porsche is staying profitable thanks to Cayenne and Panamera,not to the 911.
01-21-2013, 01:02 PM
#186
Rennlist Member
One analyst suggested that the cost difference between manufacturing a Boxster and a 911 Turbo was about $5,000-$6,000! Think about that markup...
Actually, 40K sounds pretty high to me-if you are talking actual cost. I bet its much lower. There is a lot of overhead (labor being one of them) built into GM's pricing that has nothing to do with building a vette. I also bet that high volumes and the amount of different models improve GM's ability to purchase components and amortize tooling cross-platform. There is probably way less actual vette in a vette's price than there is in a 911 price tag. Conversely, I'll guess that marketing has more to do with the pricing structure of a 911 than actual cost, especially since they have been sharing components with other models.
Last edited by LastMezger; 01-21-2013 at 02:11 PM.
01-21-2013, 01:16 PM
#187
Race Car
01-21-2013, 01:18 PM
#188
Nordschleife Master
Actually, 40K sounds pretty high to me-if you are talking actual cost. I bet its much lower. There is a lot of overhead (labor being one of them) built into GM's pricing that has nothing to do with building a vette. I also bet that high volumes and the amount of different models improve GM's ability to purchase components and amortize tooling cross-platform. There is probably way less actual vette in a vette's price than there is in a 911 price tag. Conversely, I'll guess that marketing has more to do with the pricing structure of a 911 than actual cost, especially since they have been sharing components with other models.
I believe the build quality and reliability will be concludent after a few years of ownership.
Maybe auto journalists should pick one of each and drive it daily for a couple of years in the same conditions. Then register the maintenance it's been performed,track days,observations,in service days,daily usability,cost of ownership etc. I think this would be just as interesting as the tests they run on performance and their opinions on looks.
I know that opinions from actual owners of the 2 are even more valuable,but they are also biased sometimes.
I believe Motor Trend does this for the course of 1 year with some cars.
01-21-2013, 04:00 PM
#189
Race Director
On a Porsche, it would go through the motor. And that's impossible.
I'm not trying, not at all, to argue that a Corvette is better than a Porsche. I have a 991. I haven't had a Corvette since 1996. Since then I've had only Porsches and Ferraris, usually both at the same time.
What I'm saying, is that the leaf spring argument doesn't hold water. It's just another way of showing you're not as smart as the engineers who worked on the suspension.
I'm not trying, not at all, to argue that a Corvette is better than a Porsche. I have a 991. I haven't had a Corvette since 1996. Since then I've had only Porsches and Ferraris, usually both at the same time.
What I'm saying, is that the leaf spring argument doesn't hold water. It's just another way of showing you're not as smart as the engineers who worked on the suspension.
I simply raised the obvious question as to whether they were smarter than every other car company's suspension engineers, or their own race suspension engineers, none of whom employ transverse leaf springs. Look, Porsche and Corvette have made many different design choices in producing world class performance cars; about suspension, drivetrain, materials, interior and exterior styling, what have you. Performance requirements, cost, practicality, and even tradition figured into those choices. I'm not trying to say one is "better" than the other, any more than you are. I simply prefer the Porsche approach, which is why I own a Porsche instead of a Corvette.
Last edited by Mike in CA; 01-21-2013 at 06:33 PM. Reason: sp
01-21-2013, 05:40 PM
#190
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Started to read this thread from the beginning, but it's too long and had to abort.
What I'll say is that I've been exploring what car (if any) to eventually replace our Cayman R with, mainly for track use. I'll wait until later this year to compare the options before deciding, but the new Vette is certainly among them. I anticipate that the performance will be great for the price (don't frankly care much either way about the looks or the interior), but my main concern is how durable it will be for track use. Porsches are proven to be some tough creatures for that use, Vettes maybe not so much ...
For those planning to drive only on the street, be honest with yourself. Only a fool would attempt to approach the limits of a modern sports car on public roads, so just get the car you enjoy most (within your financial means) and don't pretend that extra performance is a strong reason to prefer one over another.
What I'll say is that I've been exploring what car (if any) to eventually replace our Cayman R with, mainly for track use. I'll wait until later this year to compare the options before deciding, but the new Vette is certainly among them. I anticipate that the performance will be great for the price (don't frankly care much either way about the looks or the interior), but my main concern is how durable it will be for track use. Porsches are proven to be some tough creatures for that use, Vettes maybe not so much ...
For those planning to drive only on the street, be honest with yourself. Only a fool would attempt to approach the limits of a modern sports car on public roads, so just get the car you enjoy most (within your financial means) and don't pretend that extra performance is a strong reason to prefer one over another.
01-22-2013, 10:36 AM
#191
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How does a manufacturer set the price of the vehicle they intend to build and sell?
First they look at the market for that vehicle. For instance how many people buy a 2-seater sports car with high performance capabilities. One place Porsche and Ferrari look is at their own sales but they also look at sales of competition. Then they predict the economic forecast for when the cars will be available.
Of course the materials used to construct the car are calculated, but the factory and tooling has to be paid for as well. If the car has a 6 or 12 year lifespan, that must be paid for in that period by adding that to the materials and labor costs on each car. Then there is advertising. Ever notice just how much advertising, television, newspaper, magazine, direct mail there is for the automotive industry. It could add $1500 to the price of each car.
If they think they can produce a car that fits in the price range they are going for and still pay all their known and unknown costs, then they will price the car to sell at that price point.
Ferrari and Lamborghini sell fewer cars than Porsche so each car must pay more towards these fixed costs. So they would cost more even if the raw materials were the same. Chevrolet sells a lot of cars and trucks. Many of them share the same engines, transmissions and electronics (3 major expenses in a vehicle). These are manufactured in the same factories whether they are going in a Corvette or a Chevy truck. So each vehicle shares a smaller percentage of the factory's price.
Still, final price point is based on what they think they can get for their vehicle. And that also determines how exotic their systems are. They each have their following and they pretty much know what they are going to be able to sell.
Even though it is not going to happen, Chevrolet could probably shift more of their R&D to their truck and sedan lines and produce a Corvette of equal quality in materials and engineering to the Porsche for as little as half the price of the Porsche. Porsche would have to jump on Volkswagen engineering and parts to do the same, all the while knowing that they would lose established market share but probably gain a larger customer base because more people could afford it.
First they look at the market for that vehicle. For instance how many people buy a 2-seater sports car with high performance capabilities. One place Porsche and Ferrari look is at their own sales but they also look at sales of competition. Then they predict the economic forecast for when the cars will be available.
Of course the materials used to construct the car are calculated, but the factory and tooling has to be paid for as well. If the car has a 6 or 12 year lifespan, that must be paid for in that period by adding that to the materials and labor costs on each car. Then there is advertising. Ever notice just how much advertising, television, newspaper, magazine, direct mail there is for the automotive industry. It could add $1500 to the price of each car.
If they think they can produce a car that fits in the price range they are going for and still pay all their known and unknown costs, then they will price the car to sell at that price point.
Ferrari and Lamborghini sell fewer cars than Porsche so each car must pay more towards these fixed costs. So they would cost more even if the raw materials were the same. Chevrolet sells a lot of cars and trucks. Many of them share the same engines, transmissions and electronics (3 major expenses in a vehicle). These are manufactured in the same factories whether they are going in a Corvette or a Chevy truck. So each vehicle shares a smaller percentage of the factory's price.
Still, final price point is based on what they think they can get for their vehicle. And that also determines how exotic their systems are. They each have their following and they pretty much know what they are going to be able to sell.
Even though it is not going to happen, Chevrolet could probably shift more of their R&D to their truck and sedan lines and produce a Corvette of equal quality in materials and engineering to the Porsche for as little as half the price of the Porsche. Porsche would have to jump on Volkswagen engineering and parts to do the same, all the while knowing that they would lose established market share but probably gain a larger customer base because more people could afford it.
