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#101 bigleagueslider

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Posted 26 January 2013 - 03:57

Well, I'd love to see the argument that the Corvette is any way socially responsible..............


OK. Compare the total combined net lifetime amount of federal/state fuel taxes, registration fees, gas guzzler fees, sales taxes, etc. resulting from each Corvette sold, versus those from each Prius sold with over $10K in net taxpayer losses. In terms of benefit to society, we need more Corvettes and fewer Priuses.


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#102 Tony Matthews

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Posted 26 January 2013 - 08:57

Governments only care about raising revenue. If they reduce tax here, they raise it there, they have no option.

#103 Ross Stonefeld

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Posted 26 January 2013 - 13:11

OK. Compare the total combined net lifetime amount of federal/state fuel taxes, registration fees, gas guzzler fees, sales taxes, etc. resulting from each Corvette sold, versus those from each Prius sold with over $10K in net taxpayer losses. In terms of benefit to society, we need more Corvettes and fewer Priuses.


Why are we comparing the Corvette and the Prius only on a tax basis?

#104 MatsNorway

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Posted 26 January 2013 - 14:17



Looks good in the video i must say.

Is the guy in the video to "blame" for the targa roof?

Edited by MatsNorway, 26 January 2013 - 14:23.


#105 Magoo

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Posted 26 January 2013 - 14:59



Looks good in the video i must say.

Is the guy in the video to "blame" for the targa roof?


That's Ed Welburn, GM Vice President of Design.

#106 meb58

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Posted 26 January 2013 - 17:01

I think I compared the Corvette with a Prius. My original point was to highlight perception; that a corvette driven 3,000 miles a year compared to a Prius driven 60,000 miles a year is an interesting thought exercise...the Corvette uses less fuel but it tagged with a Gas Guzzler tax...and in my convenient scenario, the Corvette is driven by a guy who walks to work. Despite his reality, he absorbs the Guzzler tax and occasional harassment fro driving something perceived as socially irresponsible.

The trouble I have with this scenario, is that the Prius owner is the gas guzzle here, but the perception is quite the opposite. This perception makes the Corvette an easy target...policy gets made, market disappears.

Although I've conjured this from thin air, perception can invalidate the truth.

#107 Ross Stonefeld

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Posted 26 January 2013 - 17:03

Gas guzzling is usually defined as miles per gallon, not miles per week.

#108 rory57

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Posted 26 January 2013 - 17:18

ditch the rubber spring thing underneath. Its not that great of a idea? i know its light, but they switch to coilovers in racing for a reason.


Funny how often a dislike of the Corvette's composite leaf springs comes up in any 'vette discussion. I wonder why that is?

That racing 'vettes use coil springs instead is easy to understand (cheap, widely available, widely understood, practical and affordable to have unique spring rate at each corner for each track). I find the transverse (composite) leaf spring an attractive idea for a volume car and a look at the Corvette chassis shows how neatly it fits in a crowded space.

Any thoughts on why these springs are not more widely used on road vehicles? The only contemporary user I can think of is the Mercedes Sprinter van (MacPherson strut front axle).

#109 MatsNorway

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Posted 26 January 2013 - 17:32

Funny how often a dislike of the Corvette's composite leaf springs comes up in any 'vette discussion. I wonder why that is?

That racing 'vettes use coil springs instead is easy to understand (cheap, widely available, widely understood, practical and affordable to have unique spring rate at each corner for each track). I find the transverse (composite) leaf spring an attractive idea for a volume car and a look at the Corvette chassis shows how neatly it fits in a crowded space.

Any thoughts on why these springs are not more widely used on road vehicles? The only contemporary user I can think of is the Mercedes Sprinter van (MacPherson strut front axle).


I kinda like the leaf spring as a idea, as you mentioned its compact and its light. but the car becomes less tunable for the hobby tuner. As coilovers puts the load somewhere its not designed to be. And there is no custom leaf springs to buy. Also it affects roll, not sure how that works out. (possitive/negative) And the tuning marked should be considered when designing a car. The japanese manufacturers knows this.

Edited by MatsNorway, 26 January 2013 - 17:45.


#110 Canuck

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Posted 26 January 2013 - 19:25

I humbly submit that the tuner crowd as it relates to Japanese manufacturers is not now and never has been GM's target group.

#111 meb58

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Posted 26 January 2013 - 20:48

I understand...but total consumption should account for something.

Gas guzzling is usually defined as miles per gallon, not miles per week.



#112 MatsNorway

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Posted 26 January 2013 - 21:45

I humbly submit that the tuner crowd as it relates to Japanese manufacturers is not now and never has been GM's target group.


But should they?
People drop Turboes on Lamborghinis now... Its not a jap only thing.

#113 Canuck

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Posted 27 January 2013 - 03:49

I believe "jap" is perhaps an abrasive term (but I could be wrong).

The people who are throwing turbos on Lambos and whatever other supercar out there are equally qualified to forcefeed a Corvette. It is no less "tuner friendly" than any of it's peers. I would think a simple composite leaf rear suspension is much simpler to deal with than a fully magneto-resistive suspension. Besides, if folks can hack these staggeringly complicated, microprocessored-to-death cars and modify them, surely there exists the brains to deal with that little thing.

#114 phoenix101

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Posted 27 January 2013 - 07:41

Gas guzzling is usually defined as miles per gallon, not miles per week.


Jevon's paradox explains why miles-per-gallon is an insufficient measure of gasoline guzzling.

#115 MatsNorway

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Posted 27 January 2013 - 08:38

I believe "jap" is perhaps an abrasive term (but I could be wrong).

The people who are throwing turbos on Lambos and whatever other supercar out there are equally qualified to forcefeed a Corvette. It is no less "tuner friendly" than any of it's peers. I would think a simple composite leaf rear suspension is much simpler to deal with than a fully magneto-resistive suspension. Besides, if folks can hack these staggeringly complicated, microprocessored-to-death cars and modify them, surely there exists the brains to deal with that little thing.


Quality and buildfriendliness needs to be in the bottom. The Corvette engine is probably going to be success in these areas.

It seems possible to buy custom leaf springs for sport/racing applications.
http://www.ecklersco...-2005-2012.html

But people develop stuff like this too. Even for old models
Posted Image
http://www.vetteweb....on/viewall.html

However it seems that the leaf spring is heavier than the coilover springs. But since its mounted where it is perhaps it saves some chassie stiffening. giving the overall gain.
http://forums.corvet...-yes-or-no.html

Perhaps they should consider a rotating damper? Makes it a pain for the aftermarked so i hope not but it makes sense in combination with a leaf spring. btw. is it adjustment possibilities in the lower arms gearbox mounts??
Posted Image

Some of the catalog it seems.
http://i50.tinypic.com/v4rrlx.jpg

I was thinking perhaps the leaf spring was denying a low mounting of the gearbox. But it seems to not be the case on the older models.
http://www.blogcdn.c...-chassis-05.jpg

Posted Image

Edited by MatsNorway, 27 January 2013 - 09:38.


#116 Powersteer

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Posted 27 January 2013 - 12:11

The Prius Corvette argument is not plausable at all, might as well compare a Vette to a bicycle or motorcycle but then when comparing a Prius to a bicycle or economy motorcycle then it makes sense. The normal route for a Prius's A to B would be completely different to a Corvette although if comparing to a train route a Prius would be similar hence you can see a Prius/Volt sharing a garage with a Corvette when having two Corvettes only would be strange. In some circumstances the Corvette would also see A to A routes that would be a rerity on a Prius.

:cool:

#117 MatsNorway

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Posted 27 January 2013 - 17:58

OT: Rolex 24 is live
http://stream.speedtv.com/rolex24

Edited by MatsNorway, 27 January 2013 - 18:04.


#118 meb58

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Posted 27 January 2013 - 22:12

This is a perception argument, not an MPG comparison per se. The Prius in my example uses much more fuel over the course of a year than the Vette, a very plausible event. But, the owner of the Vette and his/her car are tagged as anti-social. This perception skews reality. A bicycle is not a good comparison because it does not consume fuel. And the assumption by the person driving the Prius is that the person driving the Vette will use their car for commuting...reality is skewed further still. Perhaps the Vette owner lives in a 1,000 sqft house while the Prius owner lives in a 15,000 sq ft house...the bigger house requires more fuel and electricity. This is simply a perception argument...and perception, if skewed, can result in shrinking, if not eliminating the Vette's market.

The Prius Corvette argument is not plausable at all, might as well compare a Vette to a bicycle or motorcycle but then when comparing a Prius to a bicycle or economy motorcycle then it makes sense. The normal route for a Prius's A to B would be completely different to a Corvette although if comparing to a train route a Prius would be similar hence you can see a Prius/Volt sharing a garage with a Corvette when having two Corvettes only would be strange. In some circumstances the Corvette would also see A to A routes that would be a rerity on a Prius.

:cool:


Edited by meb58, 27 January 2013 - 22:23.


#119 bigleagueslider

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Posted 28 January 2013 - 03:09

This is a perception argument, not an MPG comparison per se.......


meb58- It goes well beyond a simple comparison of MPG or fuel usage. Most importantly, we should consider the total cost/benefit to society of each vehicle. On this basis, a Prius is far less beneficial to the overall welfare of society than a Corvette. The Prius results in a net loss to taxpayers, while the Corvette results in a net gain to taxpayers.

Prius buyers have no legitimate right to feel morally superior to Corvette buyers.


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#120 Canuck

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Posted 28 January 2013 - 05:49

Perhaps, but don't go interfering with people's smug-ability by using facts. ;-)

Seems to me I recently read a muse on the efficiency of the bicycle vs. car vs. walking. When including fuel consumption of the bicycle and the walker (sure they're self-propelled but that food they eat didn't grow and deliver itself without oil somewhere unless they're bearded hippies living in a commune, growing their own food by the grace of god and not science). Seems to me the author's converted bicycling mpg wasn't as high as one would have imagined but whatever - he's probably out to lunch on one or all of his assumptions. Or not. I don't care - I don't ride my bike for any green reason. I ride it so I can continue eating doughnuts and cookies without looking like the Michelin man (130,000ish calories used last year according to Garmin). That and it's horribly addictive.

#121 phoenix101

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Posted 28 January 2013 - 08:33

meb58- It goes well beyond a simple comparison of MPG or fuel usage. Most importantly, we should consider the total cost/benefit to society of each vehicle. On this basis, a Prius is far less beneficial to the overall welfare of society than a Corvette. The Prius results in a net loss to taxpayers, while the Corvette results in a net gain to taxpayers.

Prius buyers have no legitimate right to feel morally superior to Corvette buyers.


Except your scenario isn't remotely accurate. The developed world has serious issues with petroleum balance of trade, and despite the economic rhetoric of the 1980s and 1990s, a majority of the oil we import is not an efficiently utilized input of production. Japan have a per capita oil trade deficit similar to the US. Naturally, Toyota and Honda were ahead of the game with products like the Prius and Insight.

The US currently runs a trade deficit of about $250B for crude and other petroleum products. A few billions dollars worth of Prii purchases, can make a huge difference in our trade imbalance, hence the use of federal demand subsidies. Since the geopolitics of oil is sensitive business, and since greenwashing is such a lucrative trade, governments like to tell people they are saving the planet. In reality, consumers are saving the global economy by re-balance trade in the developed world, particularly when Prius production is moved abroad.

Prius drivers do have the moral right of way, but many Prius drivers would never sully their image with dry ideas like balancing global trade or altering geopolitics between the developed and developing world. No, Prius drivers are worried about sparing mother earth from the pain of an imperceptible change in temperature. They try to save humanity from apocalyptic superstorms, when half of the world worries about eating.

If you want to make fun of most Prius buyers and the greenwashing narrative, by all means, let the vitriol fly and do not mince your words. But don't suggest the Prius is harmful to society. Prius is another long boom. Just like the long boom we started in the early 80s, when we proved we could grow and consume less oil.

#122 Magoo

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Posted 28 January 2013 - 12:26

meb58- It goes well beyond a simple comparison of MPG or fuel usage. Most importantly, we should consider the total cost/benefit to society of each vehicle. On this basis, a Prius is far less beneficial to the overall welfare of society than a Corvette. The Prius results in a net loss to taxpayers, while the Corvette results in a net gain to taxpayers.



This is an excellent example of why business people, business principles, and business values should never rule government. The purpose of statecraft is not to produce a cash profit. The purpose of statecraft, if you will, is to turn cash profits into items of actual benefit to society. Here you said "total cost/benefit to society" and "overall welfare of society," then eliminated all considerations except money.

Edited by Magoo, 28 January 2013 - 12:28.


#123 meb58

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Posted 28 January 2013 - 13:36

Really, I was only trying to highlight a little surface perception and how its effect might affect markets. I know this subject can delve deeper...

Phoenix101,

The 250B in crude costs could be eliminated if we began to explore...no...follow through with options on our own soil. ...less expensive fuel for the Corvette...ironically this might kill the Prius...interesting...there's that perception thing again.

Edited by meb58, 28 January 2013 - 13:38.


#124 phoenix101

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Posted 29 January 2013 - 00:46

Really, I was only trying to highlight a little surface perception and how its effect might affect markets. I know this subject can delve deeper...

Phoenix101,

The 250B in crude costs could be eliminated if we began to explore...no...follow through with options on our own soil. ...less expensive fuel for the Corvette...ironically this might kill the Prius...interesting...there's that perception thing again.


US oil production has been skyrocketing since 2009. The EIA and other credible institutions estimate that the US could return to 11m bbl/day by 2020. If we are able to achieve that feat, and oil consumption remained unchanged, we'd still be about 8m bbl/day short of our daily consumption rate. That's why we have CAFE 2025. Furthermore, production costs are quite high so we can't really count on a sustained reduction in oil price to close our deficit. Tight oil in the Bakken is certainly not going to bring costs down substantially.

The environmental impact of various automobiles and the concept of green motoring is a matter of perception. Oil production, oil consumption, and US imbalance of trade of trade for oil is not really open for interpretation. The value of fuel-efficient vehicles is not really open for interpretation.

If you understood the pro-poverty argument you were making, you would not be making it. If we eliminated our oil trade deficit, and we re-allocated our refinery capacity to gasoline exports, the US would experience an economic effect similar to 2% GDP growth. We'd also be halfway to eliminating our trade deficit. What are people waiting for? That is the pertinent question.

Regarding the Corvette, I don't care if people own them, particularly not the the method you describe (weekend driving). Furthermore, we have the technology to eclipse 40mpg EPA rating so sportscars should become less and less troublesome as polluters and gas guzzlers. I guess it depends on the choices made by the auto companies.

#125 Canuck

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Posted 29 January 2013 - 02:34

You'll be royally eff'd if there's a successful Ghadafiesque push to trade oil in Euros. Why the USD remains a haven currency is beyond me - there's only two exports to be had these days, weapons and Hollywood. You don't have enough oil to meet your own demands, you're facing a serious water issue in the coming future and successive governments have allowed corporations to not only become "too big to fail", but to export any real industry at the same time. You make movies and money. One of them is a completely fantastical creation of no value and the other is mind-numbing entertainment.

The threat to the US economy is not oil imports, it's job exports. If you don't export anything, no amount of fuel conservation is going to fix the trade imbalance.

#126 Greg Locock

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Posted 29 January 2013 - 02:47

So far as the leaf spring goes, there's no great engineering rationale for retaining it, plenty of people manage to keep the back ends of sports cars off the ground without one, but corporate egoes will insist it is part of the heritage.

Here's a rough list of pros and cons

+++ integrate leaf spring into supension, so don't need an arm, so lighter, cheaper

- effective front view geoemtry may not be as easy to identify (ie what is the effective arm length)

--glass fibre spring inherently more difficult to design, may not be any lighter than a coil spring, certainly far more expensive

--package eats either ground clearance or floorpan

--needs new structure to get to side rails, coils take vertical laods direct to rails, chances are you already have a hardpoint there for the shocks.

--gf/epoxy has higher inherent damping than steel so smooth road ride will suffer

+ tends to give rising rate

I've looked at composite leaf springs a few times for various jobs, thus far steel has always won, but if you are working on new concepts (which I don't any longer) you don't reject new architectures until you have to. GF leafsprings have been around for donkey's years in the UK on one line of light truck, but nobody seems in any great rush to use them. I have just thought of another reason why they are less attractive - if the leaf fails then the suspension doesn't just fall onto its bump stops, the wheel flips out. So your FMEA will insist that the leaf spring is further overdesigned, increasing cost and weight.






#127 MatsNorway

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Posted 29 January 2013 - 06:25

So far as the leaf spring goes, there's no great engineering rationale for retaining it, plenty of people manage to keep the back ends of sports cars off the ground without one, but corporate egoes will insist it is part of the heritage.

Here's a rough list of pros and cons

+++ integrate leaf spring into supension, so don't need an arm, so lighter, cheaper

- effective front view geoemtry may not be as easy to identify (ie what is the effective arm length)

--glass fibre spring inherently more difficult to design, may not be any lighter than a coil spring, certainly far more expensive

--package eats either ground clearance or floorpan

--needs new structure to get to side rails, coils take vertical laods direct to rails, chances are you already have a hardpoint there for the shocks.

--gf/epoxy has higher inherent damping than steel so smooth road ride will suffer

+ tends to give rising rate

I've looked at composite leaf springs a few times for various jobs, thus far steel has always won, but if you are working on new concepts (which I don't any longer) you don't reject new architectures until you have to. GF leafsprings have been around for donkey's years in the UK on one line of light truck, but nobody seems in any great rush to use them. I have just thought of another reason why they are less attractive - if the leaf fails then the suspension doesn't just fall onto its bump stops, the wheel flips out. So your FMEA will insist that the leaf spring is further overdesigned, increasing cost and weight.


Thankt you for bringing the corvette back in topic. To all you fuel bastards.. make a new thread.
I forgot they have Leaf springs in the front too. Thats probably a bigger deficit than having the rear springs. (was deficit a usable word here?)

If they used rotating dampers. Would it make any more sence then? alternativily cantilever to mount the dampers flatt underneath. With that i recon it would make even more sence to have regular springs.

#128 phoenix101

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Posted 29 January 2013 - 07:38

You'll be royally eff'd if there's a successful Ghadafiesque push to trade oil in Euros. Why the USD remains a haven currency is beyond me - there's only two exports to be had these days, weapons and Hollywood. You don't have enough oil to meet your own demands, you're facing a serious water issue in the coming future and successive governments have allowed corporations to not only become "too big to fail", but to export any real industry at the same time. You make movies and money. One of them is a completely fantastical creation of no value and the other is mind-numbing entertainment.

The threat to the US economy is not oil imports, it's job exports. If you don't export anything, no amount of fuel conservation is going to fix the trade imbalance.


You've obviously not looked at US trade data.

The US dollar is the global reserve currency b/c manipulating its value allows foreign nations to siphon money out of our economy. Since 2000, the US has run a cumulative trade deficit of over $8T. Our currency should be worthless, but many countries have a vested interest in propping up the dollar so they can sell us oil, cars, computer/telecom equipment, consumer electronics, and cheap Walmart goods. As long as our currency is artificially strong, foreign goods can get in and our jobs can leave. Artificial currency valuation also makes it difficult for the US to export.

Long story short, those days will soon be gone. Germany and Japan have been told to build auto plants in NAFTA countries. Honda, Mazda, Audi, VW, and BMW are all building in Mexico. Nissan is reallocating production to Canton, OH and Smyrna, TN. Subaru are building in Indiana. Toyota are finally completing the Prius plant in Mississippi. The US is drilling and fracking, which means we will buy significantly less energy from Canada, Mexico, Venezuela, and Saudi Arabia. Natural gas production will make industrial electricity considerably cheaper, and if Obamacare doesn't suck (50/50 chance), labor overhead should decline. Manufacturing will come back to the US.

China should take care of itself. Wages and industrial real estate are becoming cost prohibitive, and the renminbi is slowly appreciating to its appropriate value. China will buy our passenger cars and planes to keep their currency in check or US companies will start allocating production to South/Central America.

#129 meb58

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Posted 29 January 2013 - 15:39

I'm the chief bastard. New thread started - Gas Guzzler Tax, mpg and the fate of the auto...I sent the OP an apology yesterday.

Thankt you for bringing the corvette back in topic. To all you fuel bastards.. make a new thread.
I forgot they have Leaf springs in the front too. Thats probably a bigger deficit than having the rear springs. (was deficit a usable word here?)

If they used rotating dampers. Would it make any more sence then? alternativily cantilever to mount the dampers flatt underneath. With that i recon it would make even more sence to have regular springs.


Edited by meb58, 29 January 2013 - 15:45.


#130 blkirk

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Posted 29 January 2013 - 18:38

So far as the leaf spring goes, there's no great engineering rationale for retaining it, plenty of people manage to keep the back ends of sports cars off the ground without one, but corporate egoes will insist it is part of the heritage.

Here's a rough list of pros and cons

+++ integrate leaf spring into supension, so don't need an arm, so lighter, cheaper

- effective front view geoemtry may not be as easy to identify (ie what is the effective arm length)

--glass fibre spring inherently more difficult to design, may not be any lighter than a coil spring, certainly far more expensive

--package eats either ground clearance or floorpan

--needs new structure to get to side rails, coils take vertical laods direct to rails, chances are you already have a hardpoint there for the shocks.

--gf/epoxy has higher inherent damping than steel so smooth road ride will suffer

+ tends to give rising rate

I've looked at composite leaf springs a few times for various jobs, thus far steel has always won, but if you are working on new concepts (which I don't any longer) you don't reject new architectures until you have to. GF leafsprings have been around for donkey's years in the UK on one line of light truck, but nobody seems in any great rush to use them. I have just thought of another reason why they are less attractive - if the leaf fails then the suspension doesn't just fall onto its bump stops, the wheel flips out. So your FMEA will insist that the leaf spring is further overdesigned, increasing cost and weight.


Once upon a time, I looked at replacing steel multi-leaf truck springs with a monolithic fiberglass spring. The fiberglass spring was much lighter than the steel, and it had no internal stiction, so it gave a better ride. The fiberglass won out on everything except lateral stability. The spring wasn't wide enough to keep the truck from wagging its tail. By the time you add in a Panhard link (or equivalent) to keep the axle in place relative to the body, all the benefits are gone.

Posted Image

At least on the Vette, the spring does not act as a suspension link. So no worries about wheels flipping out due to spring failure. And if you've never seen properly made fiberglass fail in fatigue, it's a very gradual process. The car will end up sitting on the ground before the spring fails in fatigue.

#131 Greg Locock

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Posted 30 January 2013 - 00:12

At least on the Vette, the spring does not act as a suspension link. So no worries about wheels flipping out due to spring failure. And if you've never seen properly made fiberglass fail in fatigue, it's a very gradual process. The car will end up sitting on the ground before the spring fails in fatigue.



The pimary mode of failure that gives people heeby jeebies is cracking from a notch from road damage. That being said I expect the weight saving will appeal more and more.

If the Corvette doesn't use the leaf spring as an arm then I'd say it is very hard to justify it for all those -- reasons I gave. However it then boils down to packaging, and in a relatively extravagant package like a modern Corvette, the odd few wasted litres are less of a deal than in an econobox, or for that matter a light truck.



#132 Lee Nicolle

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Posted 30 January 2013 - 01:21

I agree that the Vette transverse spring is an anochrism. A coil spring rides better, is more adjustable and is probably lighter too. And uses less space as Greg said. So why do GM persist, early Vettes were coil front and longitudional leaves rear.Like the family Chev. So hardly heriditary, and even then why?
Though to be fair it does work extremely well,, but is still archaic.
Still Porkers still have that lump way behind the rear wheels, seemingly they have engineered the cars well around it,, but again Why? again it makes no sense.
As a matter of interest though, a multi leaf spring is self damping. You can drive without a shock. As are most trailers. A coil is so shock dominated. The single leaf fibreglass spring cannot be too bad as a damper either. I had a supplier here recently with an old overloaded Benz van and one shocker was broken totally. The guy did not even realise, he said it was a bit 'wavy' Unsurprisingly!

#133 desmo

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Posted 30 January 2013 - 03:18

A coil spring rides better, is more adjustable and is probably lighter too.

I'm wondering what you base these assertions on? For "ride" isn't any spring of a given rate essentially the same, slight material hysteresis differences perhaps aside? And coils springs are hardly simply "adjustable". What can you adjust other than preload--which isn't a spring adjustment as much as a mount adjustment in any case? Why would a steel coil be lighter?


#134 Greg Locock

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Posted 30 January 2013 - 03:30

I'm wondering what you base these assertions on? For "ride" isn't any spring of a given rate essentially the same, slight material hysteresis differences perhaps aside? And coils springs are hardly simply "adjustable". What can you adjust other than preload--which isn't a spring adjustment as much as a mount adjustment in any case? Why would a steel coil be lighter?


For "ride" isn't any spring of a given rate essentially the same, slight material hysteresis differences perhaps aside?

And that is the crucial difference.


Why would a steel coil be lighter?

(a) smaller factor of safety (b) no need to reinforce at contact points (impedance mismatch problem). The latter is basically how do you get the stress out through the thickness of the spring into the point at which it contacts the chassis. It is a solvable problem, but it is extra material the steel spring doesn't need.

Also designing mono leaf springs that are weight effective is not quite as easy as you might hope, that's why we use multileaf steel springs, or coil springs, both of which use much of the material very effectively.

How much does a corvette leaf weigh? what rate is it? what travel? what static load? If somebody knows all that I could knock out a coil spring equivalent.

http://www.google.co...vCAdbh97ZRBHsaw

claims a 66% weight save for 2 coils vs one leaf. The cynic in me wonders if light weight was a design parameter for the coil spring, it often is not.

Edited by Greg Locock, 30 January 2013 - 03:41.


#135 bigleagueslider

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Posted 30 January 2013 - 04:18

Except your scenario isn't remotely accurate. The developed world has serious issues with petroleum balance of trade, and despite the economic rhetoric of the 1980s and 1990s, a majority of the oil we import is not an efficiently utilized input of production. Japan have a per capita oil trade deficit similar to the US. Naturally, Toyota and Honda were ahead of the game with products like the Prius and Insight.

The US currently runs a trade deficit of about $250B for crude and other petroleum products. A few billions dollars worth of Prii purchases, can make a huge difference in our trade imbalance, hence the use of federal demand subsidies. Since the geopolitics of oil is sensitive business, and since greenwashing is such a lucrative trade, governments like to tell people they are saving the planet. In reality, consumers are saving the global economy by re-balance trade in the developed world, particularly when Prius production is moved abroad.

Prius drivers do have the moral right of way, but many Prius drivers would never sully their image with dry ideas like balancing global trade or altering geopolitics between the developed and developing world. No, Prius drivers are worried about sparing mother earth from the pain of an imperceptible change in temperature. They try to save humanity from apocalyptic superstorms, when half of the world worries about eating.

If you want to make fun of most Prius buyers and the greenwashing narrative, by all means, let the vitriol fly and do not mince your words. But don't suggest the Prius is harmful to society. Prius is another long boom. Just like the long boom we started in the early 80s, when we proved we could grow and consume less oil.


phoenix101-

Take it easy. While you claim my comments are not "remotely accurate", I would say the same about yours.

First you claim that the current US crude oil economic trade deficit is a bad thing. The truth is that the US currently has sufficient domestic oil reserves to supply 100% of our annual domestic consumption for over 150 years. The reason we import oil rather than producing domestically is because it is currently more economical to do so.

Second, if a trade deficit from oil imports is bad for the US economy, wouldn't a trade deficit from Prius and Insight imports also be bad?

Third, one of the most valuable sources of US exports are commercial jet aircraft and engines. Which, by the way, depend on huge amounts of crude oil for fuel.

Finally, I never suggested that "the Prius was harmful to society". Instead, I simply pointed out that many people failed to appreciate that the Corvette provided certain economic advantages to society versus the Prius.

Regards,
slider


#136 MatsNorway

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Posted 30 January 2013 - 15:05

Regards,
slider


Continuation of that is in the new thread..
http://forums.autosp...howtopic=180426


Edited by MatsNorway, 30 January 2013 - 15:07.


#137 meb58

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Posted 30 January 2013 - 16:56

Isn't it a stretch to call this (Corvette) mono-leaf spring set up independent? ...unless it acts as a torsion bar...by virtue of how it is attached to the car...

For "ride" isn't any spring of a given rate essentially the same, slight material hysteresis differences perhaps aside?

And that is the crucial difference.


Why would a steel coil be lighter?

(a) smaller factor of safety (b) no need to reinforce at contact points (impedance mismatch problem). The latter is basically how do you get the stress out through the thickness of the spring into the point at which it contacts the chassis. It is a solvable problem, but it is extra material the steel spring doesn't need.

Also designing mono leaf springs that are weight effective is not quite as easy as you might hope, that's why we use multileaf steel springs, or coil springs, both of which use much of the material very effectively.

How much does a corvette leaf weigh? what rate is it? what travel? what static load? If somebody knows all that I could knock out a coil spring equivalent.

http://www.google.co...vCAdbh97ZRBHsaw

claims a 66% weight save for 2 coils vs one leaf. The cynic in me wonders if light weight was a design parameter for the coil spring, it often is not.


Edited by meb58, 30 January 2013 - 16:56.


#138 gruntguru

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Posted 30 January 2013 - 23:38

Isn't it a stretch to call this (Corvette) mono-leaf spring set up independent? ...unless it acts as a torsion bar...by virtue of how it is attached to the car...

Because the centre of the leaf spring is rigidly attached to the chassis it is effectively two springs - one for each wheel and thus fully independent.

#139 Greg Locock

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Posted 30 January 2013 - 23:56

Because the centre of the leaf spring is rigidly attached to the chassis it is effectively two springs - one for each wheel and thus fully independent.

Even if it wasn't and allowed some crosstalk it would act as a pro roll bar, a good thing for traction on rough roads at least.

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#140 Lee Nicolle

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Posted 31 January 2013 - 09:49

I'm wondering what you base these assertions on? For "ride" isn't any spring of a given rate essentially the same, slight material hysteresis differences perhaps aside? And coils springs are hardly simply "adjustable". What can you adjust other than preload--which isn't a spring adjustment as much as a mount adjustment in any case? Why would a steel coil be lighter?

Clearly you have not compared the hundreds of models that use both. The ride of a coil will always be superior, though the load carrying capacity of multi leaf will always be superior.And that is not saying that either are terrible, they are not. A coil will carry a fair load, a leaf does not ride terribly. And a leaf will always be simpler and probably be more robust.
A Vette with its slightly weird transverse monoleaf [for modern times] is a different beast, proven that it works, ride for a Sports Car is surprisingly good. Better than some sporty passenger cars. At least on a dry city road, that is the extent of my later Corvette experience. A 70s Vette has those big tyres to damp out the bumps!

#141 blkirk

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Posted 31 January 2013 - 17:40

Because the centre of the leaf spring is rigidly attached to the chassis it is effectively two springs - one for each wheel and thus fully independent.


The Corvette leaf is actually mounted to the chassis at two points. This puts it in 4-point bending. The part of the spring that is between the two mounts is equally loaded. This makes it more efficient than a center mounted mono-leaf spring. It also gives is a slight anti-roll effect. If you push up on one side, the other side goes up, too.

Posted Image

Edit: This Wikipedia page covers the topic pretty well, including its shortcomings. http://en.wikipedia....tte_leaf_spring

Edited by blkirk, 31 January 2013 - 17:48.


#142 Greg Locock

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Posted 31 January 2013 - 23:14

Thanks that makes sense of some of the pro and anti arguments. If they could blow the sta bar away that is a HUGE packaging (10 l), weight (2-5kg) and cost ($40-60)advantage for a typical car.

Edited by Greg Locock, 31 January 2013 - 23:21.


#143 Lee Nicolle

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Posted 01 February 2013 - 02:01

Having never worked on, or even crawled under a later Vette [they are way to close to the ground] I am surprised that the ride is so good. The seemingly semi 'bound up' spring very thinly insulated from the crossmember should make it ride like a dray. Which they do not. I have driven a 2000 [or so] model and ridden in several for 68 thru to about 04. And while I find them uncomfortable for my geriatric body they do actually ride and drive nice. For a sports car!!


#144 bigleagueslider

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Posted 01 February 2013 - 04:44

Because the centre of the leaf spring is rigidly attached to the chassis it is effectively two springs - one for each wheel and thus fully independent.


Technically, the Corvette single rear transverse leaf spring is not rigidly attached, it is mounted in elastomeric bushings. Regardless, if there were only a single central attachment, the leaf spring would function more like a roll bar than a suspension spring. The single central pivot would simply act as a fulcrum point. But even with two laterally offset mounts, due to the fact that the leaf spring is somewhat free to rotate, twist and translate within the elastomer bushings, it still is not comparable to a conventional coil spring arrangement.


#145 gruntguru

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Posted 01 February 2013 - 05:56

Technically, the Corvette single rear transverse leaf spring is not rigidly attached, it is mounted in elastomeric bushings. Regardless, if there were only a single central attachment, the leaf spring would function more like a roll bar than a suspension spring. The single central pivot would simply act as a fulcrum point. But even with two laterally offset mounts, due to the fact that the leaf spring is somewhat free to rotate, twist and translate within the elastomer bushings, it still is not comparable to a conventional coil spring arrangement.

See post #141.

#146 Kelpiecross

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Posted 01 February 2013 - 11:52


Despite all the engineering debate about the fibreglass springs I think Chevrolet uses them simply because it is part of the Corvette's "image" - fibreglass body/fibreglass springs. If they used no fibreglass at all either in the body or the springs etc. the Corvette would be just another Chevrolet.


#147 MatsNorway

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Posted 01 February 2013 - 13:07

Despite all the engineering debate about the fibreglass springs I think Chevrolet uses them simply because it is part of the Corvette's "image" - fibreglass body/fibreglass springs. If they used no fibreglass at all either in the body or the springs etc. the Corvette would be just another Chevrolet.

I find this silly but im not american so i don`t know anything about the corvettes image.

Edited by MatsNorway, 01 February 2013 - 13:08.


#148 meb58

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Posted 01 February 2013 - 17:51

I might find the car more appealing if it's entire body were made from high strength steel...a prejudice not supported by anything technical. Though I do wonder if Chevrolet could save weight by using all steel...

#149 Bob Riebe

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Posted 01 February 2013 - 19:54

I might find the car more appealing if it's entire body were made from high strength steel...a prejudice not supported by anything technical. Though I do wonder if Chevrolet could save weight by using all steel...

You forget that the cancer that affects cars sold north or mid-Iowa would then make lots with rust-bucket Corvettes a rather pathetic sight.

#150 Canuck

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Posted 02 February 2013 - 03:23

Fibreglass rots too. Vettes don't need rust to look dilapidated and neglected.