2014 C7 Chevrolet Corvette

[ZDan]

Originally Posted by vtmike

What's the point of a 450hp 3200 pound car if you never take it to the track.

You MUST be joking. The Corvette is a VERY capable track car.

A car of this caliber should be track oriented.

It is.

So I think the C7 should be talked about from a track prospective.

That's "perspective".

That's the reason I bought a frs and am on this forum. It is fun to drive within reasonable speeds on public roads. (also on the track)

I don't see how you could seriously consider tracking such a car. I mean, it's on STRUTS for God's sake. Totally unsuitable and "wrong"... [sarcasm off]

I understand the pros and cons of the suspension set ups and the coil spring setup is superior in my opinion when comparing them in any application of a high performance car.

Never mind the facts, your mind is made up!

While I am an engineer, I'm not an automotive engineer. I doubt you or any other person replying to this thread is an automotive engineer designing suspension components for any major auto manufacturer or as qualified as those who do.

I'm an aerospace engineer, working in the automotive industry (er, motorcycle industry), and design, analyze, optimize chassis and suspension systems. I ordered several sets of custom coilover shocks just this morning for suspension development for the new vehicle project I'm currently working on.

The best way I see to empirically get results on the matter based on those engineers who are qualified to design such suspensions rather than the theoretical benefits based on our limited knowledge is to see what conclusions these engineers have come to. I don't see how this is not sound logic.

Because what works, WORKS, whether you or I or anyone else thinks it should or not. The Corvette's leaf springs freaking WORK.

The results: overwhelmingly engineers for companies all over the world for all types of performance cars (mid rwd, front rwd, front awd, front fwd, i6, v8, v6, i4, flat 4, flat 6, v12, v10, 2-5 doors, 1900lbs-4000+lbs) all use coil springs for at least the front and some times torsion beam rear suspension.

The universe of physical laws doesn't give a rats arse about what the overwhelming majority uses. The Corvette performs extremely well with leaf springs. And *any*one with an iota of understanding can easily understand why leafs vs. coils to provide force/distance restoring force in the suspension really isn't that big a deal, not *nearly* as big a deal as dozens of other factors.

Your argument that "everybody else uses method X, therefore method Y must suck" is totally invalid.

[SubieNate]

@ZDan-Aerospace Engineer here too.

I hate to play this card, but maybe we have a case of, "I'm an engineer, and they didn't engineer it the way I would, so it must be wrong" going on here.

[vtmike]

Originally Posted by ZDan

You MUST be joking. The Corvette is a VERY capable track car.

That was my point. It should be considered in context to the track not street.








Your argument that "everybody else uses method X, therefore method Y must suck" is totally invalid.

I disagree. In any industry people borrow/steal what ever overwhelmingly works best. I don't see any body "borrowing" Chevy's design.

And for some empirical data.

http://www.motortrend.com/features/1...r/viewall.html

What do you know, the corvette didn't do well even though posting a good lap time.

http://www.motortrend.com/features/p...n/viewall.html

Corvette wasn't in this one but shows fastest and most grip does not equal good handling.


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[Dimman]

Originally Posted by ZDan

But they WORK, and very well, for their intended usage. So what's the problem? Why do you insist that a different approach, that WORKS, should be abandoned?

Don't get me started! Again, it's a different approach, that WORKS, and quite well. Why should every manufacturer CONFORM to the same solutions?

What compelling reason would they have to change?

They won races/championships (with a huge displacement advantage), and they lost them as well (notably when Colin Edwards beat Troy Bayliss).
They didn't prove superiority, they did prove that it was a viable *different* approach.

ONce more: What is "better" for a production supercar doesnt' necessarily apply to a pure RACE car that has to be tuneable to the nth degree. There are practical (and possibly rules) reasons that the C6R is on coils.

No, they showed (and show) that it is a viable, competitive alternative. For many years they enjoyed a HUGE displacement advantage (1000cc for twins vs. 750cc for the 4s). And when Honda decided to run a Vtwin (non-desmo) as well, to get the same advantage, they beat Ducati in SBK.

All this obsession over how one method, one way, MUST be "BEST". It's just not true! There is no one way!


Seems a strange distinction to make...

Because I feel they 'believe' in the OHV setup, but not the springs.


Ducati didn't just shrug at engine development because they had a displacement advantage. They believed that the desmo was best. For what it's worth the 750cc L4s still raped them on the straights, and the V2's advantages were it's low-end response, packaging, low CoG, and balance that allowed them to put power down out of the corners. (Sounds rather familiar, including the displacement advantage, heh...) They needed power up top, and felt desmo would be their best option. Not to be different. Then Honda brought out the RC51.

So saying that Ducati didn't have to put a world class attempt-to-be-the-best effort in because of displacement advantage is a bit rude to their engineers, and by logical association, to GM as well.

Ignoring the same but different (except for manufacturing and development costs) of the springs and going back to the large displacement OHV V8 again, we can see a glimpse of where an increasing weakness of it may appear. The Ducati v Honda example shows what may happen as DOHC motors approach, but don't match the OHV in displacement. There is probably a 'sweet spot' for GMs V8 in terms of displacement to power to physical size. Getting bigger than 7L will keep cutting into high rpm efficiency, from bore/combustion speed limits, thermal losses, piston speeds from increase stroke, as well as the external size growth that bigger bore and stroke will require. So depending on how fast they both increase their efficiency, there will probably be a point where the efficiency increases of the DOHC will completely annul all of the OHVs benefits. The Coyote is closing in on the weight fast, and stretching the efficiency gap faster. So there will probably soon be a point where a DOHC will be smaller and lighter, with a smaller displacement that still outperforms the OHV in every category.

That GM is still in the game reflects a couple things. First that they have some really good airflow and combustion engineers. But, given the rest of GM's shit line-up, they are throwing a fuck ton of money away because of their pride. The amount of one-off crazy tech that GM throws at the Vette, that will not or cannot trickle down to their cars that are supposed to make them money, is shaneful. And one of the best technologies that they did develop got sold to the Chinese.








Also: bailout.

[ZDan]

Originally Posted by vtmike

I disagree. In any industry people borrow/steal what ever overwhelmingly works best. I don't see any body "borrowing" Chevy's design.

That doesn't mean it doesnt WORK! You can't be much of an engineer if your approach to a design solution begins and ends with: "well, what's the majority using?". Of course it makes sense and is conservative to stick with the most popular solutions, but that doesn't mean there aren't other viable approaches.

And for some empirical data.

http://www.motortrend.com/features/1...r/viewall.html

What do you know, the corvette didn't do well even though posting a good lap time.

Not going to the link, not gonna read, but lemme guess, if they LOVEd the handling but it posted a slower lap time, then all we'd be hearing about was the slow lap time.

http://www.motortrend.com/features/p...n/viewall.html

Corvette wasn't in this one but shows fastest and most grip does not equal good handling.

Ah, now a comparison without a Corvette, with great-grip cars on COIL springs that don't have "good handling", as further evidence that LEAF springs suck?!

Laughable.

There are SO MANY OTHER factors that influence handling than whether the spring is a coil or a composite leaf. An OVERWHELMING number of factors that have HUGELY greater impact.

damping profiles
bushing stiffnesses (in all axes)
wishbones or struts or ???
how much (if any) ackerman?
toe curves
camber curves
other geometry
c.g. height
weight distribution

And of course
TIRES.

Leaf springs on the Corvette are not a problem for the car, other than one of perception.

And it's a PISS poor engineering approach that prefers a popularity contest to actual analysis, or even "emperical results" (which you repeatedly claim to rely on, but clearly you are freely interpreting according to your INCREDIBLY and indefensibly strong BIAS against the use of composite leafs as springs in automotive suspensions).

whew...

[vtmike]

Originally Posted by ZDan

That doesn't mean it doesnt WORK! You can't be much of an engineer if your approach to a design solution begins and ends with: "well, what's the majority using?". Of course it makes sense and is conservative to stick with the most popular solutions, but that doesn't mean there aren't other viable approaches.

And for some empirical data.

Not going to the link, not gonna read, but lemme guess, if they LOVEd the handling but it posted a slower lap time, then all we'd be hearing about was the slow lap time.

Ah, now a comparison without a Corvette, with great-grip cars on COIL springs that don't have "good handling", as further evidence that LEAF springs suck?!

Laughable.

There are SO MANY OTHER factors that influence handling than whether the spring is a coil or a composite leaf. An OVERWHELMING number of factors that have HUGELY greater impact.

damping profiles
bushing stiffnesses (in all axes)
wishbones or struts or ???
how much (if any) ackerman?
toe curves
camber curves
other geometry
c.g. height
weight distribution

And of course
TIRES.

Leaf springs on the Corvette are not a problem for the car, other than one of perception.

And it's a PISS poor engineering approach that prefers a popularity contest to actual analysis, or even "emperical results" (which you repeatedly claim to rely on, but clearly you are freely interpreting according to your INCREDIBLY and indefensibly strong BIAS against the use of composite leafs as springs in automotive suspensions).

whew...

Wrong. The Corvette wasn't the fastest. The gt3 was and also happened to win the comparison. Corvette was second fastest and the driver did not care for it. Instrument readings supposedly backed up subjective rating.

Second one the fastest car (viper acr) did not win. R8 won this one.

These are the only comparisons I could think of that tried to test cars on the merits of their handling alone and use both subjective ratings and instrument testing of cars in stock form. There were cars with way less grip and worse track times that faired well (rx8. )

I haven't seen you post any data from testing in defense of the leaf spring other than theory. I would love to see some solid figures in defense of your opinion.

Track times alone are not an indication of handling well. Most all reviews I see for various trim Corvettes are its fast and has lots of grip but not pleasing to drive because of its unrefined handling characteristics. Being that is the only car with that suspension setup I have no other car to form a different opinion of transverse leaf springs.







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[OrbitalEllipses]

I've definitely been educated on transverse leaf springs since opening this thread. I always wondered how Corvettes could come with truck suspension...I guess they don't!

[Gixxersixxerman]

Originally Posted by Dimman

As to the Ducati analogy, do they change to pneumatic valves or keep the desmo system when they race?

I know know anything about car suspension, I've learned a bit here.. But motorcycles... That's my strong point.. To answer your question, yes Ducati still uses the desmodromic valve actuation in racing.. In world super bike, because that's what comes stock on the bikes and in Motogp.. Since 2003 the desmosedici had a limit around 18,000 rpm with the 990cc engines... They didn't necessarily run that high... The 800cc engines have a gauge that shows up to 19,000 rpm, but as of the last edition of moto GP technology it's unclear whether the engine seen it or not, some speculate that it's a race machine and unlike production machines, they don't need to put numbers after the redline for a more symmetrical appearance like in a car that redlines at 7 but goes to 9..

Yamaha red limit is around 17,500 with steel springs when it was first brought to 800cc.. Afterwards 19,000 with pneumatic valves

Honda was running at 17k to then managed upwards of 19k with steel springs.. They switched to pneumatic more then once but lost midrange and the riders didn't like it.. They meantioned pneumatic springs afterwards at different times, and I'm sure they are running them.. But the factories are more tight lipped then ever since everything has gotten so close between the top two machines


Anyways.. Hope that helps you a bit..

[vtmike]

Originally Posted by LSxJunkie

Randy Pobst was the hotshoe for that test. That test was with a Z06 on GoodYears.

http://www.motortrend.com/roadtests/...#ixzz2IIoHh38m

He was also the hotshoe for this test. This was a ZR1 on Michelins. Up against a new 2013 Viper, which is the most honest apples to apples test. Similar weight, virtually identical power, front engine, RWD, one has coils and the other has leafs. Another good test would be a 599 GTO, but nobody's ever compared the two. As an engineer, I'm sure you care about testing standards and objectivity, things like minimizing variables. Right?

Now onto the juicy bit, the stuff from Randy Pobst.


Oh look, the transverse leaf springs were a NONFACTOR. You care more about them than a race car driver who will push this thing at 10/10ths.

Other notes from Randy Pobst on the 2012 Z06 with Michelin Sport Cups.

And there's one variable you keep forgetting here. Almost none of the other cars you've compared make torque at corner exit like an LS7 or an LS9 does. Of course that's going to lead to power oversteer, which combined with the awful breakaway characteristics of the GoodYears is going to lead to the twitchiness you've read about in reviews of Z06s from 2006-2010.


This is starting to feel like you initially thought that the Corvette came with this



and you formed your vitriolic opinion based on that and when you were informed that it didn't, you had to scramble to defend your opinion by bashing transverse leaf springs, which you clearly know nothing about, not on the merits, but on a misguided assumption that "this isn't what everyone else is doing so it must be worse."

To support this, you've repeatedly referenced reviews about handling characteristics that have nothing to do with transverse leaf springs. There is a reason that nobody talks about them. People who are much better versed in making cars go fast, driving cars fast, and telling the public what fast cars are about have figured out that the transverse leaf spring is a nonfactor. Spring RATE is a factor, but nobody mentions that either. Discussions are all based on the actual factors, damping and tires. However, pedants like yourself seem to want to make an issue of it.

You and I are not going to agree. But, on Randy Pobst, his review that you quoted was not praising of the handling of the z06.

Here is what he had to say to wrap things up.


Overall... "I'll tell you what, much easier car to drive on R-compound tires. I felt like the car was really fast. It was generating a lot of grip. The Corvette is far better on this tire. It can handle the power. It kinda felt a little bit soft, which makes you feel a little bit...dull around the edges. There's less precision in the movements than other cars here."

Key part is: It kinda felt a little bit soft, which makes you feel a little bit...dull around the edges. There's less precision in the movements than other cars here."

Didn't measure up to the competition there in the handling department.

The viper is another one of those cars known for its numbers but not driving experience.

The magnetic shocks make a huge difference for the Vette that the viper doesn't have. They mentioned that in the article and also the ceramic brakes (viper also doesn't have) being a factor in inspiring confidence with the Vette.

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[vtmike]

Originally Posted by LSxJunkie

Yup, you highlighted it. Softer. Spring RATE. Not spring design.

10:23 Randy Pobst - "It's a lotta work, it's a brutal car, REALLY enjoyable though." His emphasis. Not mine.

Dull around the edges, less precision in movement than the other cars.

What ever the cause it wasn't as good as the competition.

Also brutal and a lot of work are not generally good attributes.

I have yet to see a review (from reputable 3rd party neutral source, not gm/Corvette magazines) of any factory Corvette that has all good things to say about the handling without major negative caveats.

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[Rayme]

You guys need to go grab a beer.

[Mitch]

This is why we can't have nice things.

[ZDan]

Originally Posted by vtmike

Wrong. The Corvette wasn't the fastest.

WTH?! I never said it was! I specifically said I didn't read the article! I said that *if* it had posted a slow lap, then you would be on that. In your post, you said it did post a "fast lap".

I never said or implied that the Corvette was "fastest".

The gt3 was and also happened to win the comparison. Corvette was second fastest and the driver did not care for it. Instrument readings supposedly backed up subjective rating.

And this says absolutely nothing about whether coils are better than leafs as springs. Or, indeed, whether struts are better than double-wishbones...

Second one the fastest car (viper acr) did not win. R8 won this one.

These are the only comparisons I could think of that tried to test cars on the merits of their handling alone and use both subjective ratings and instrument testing of cars in stock form. There were cars with way less grip and worse track times that faired well (rx8. )

You mean "fared well".
Anyway, you must surely admit that it is a little bit nutty to look at a comparison of cars that are ALL on coil springs, and suggest that the results imply coil superiority over leaf springs!

I haven't seen you post any data from testing in defense of the leaf spring other than theory. I would love to see some solid figures in defense of your opinion.

You *really* think that the above referenced comparison tests say anything at all about leafs vs. coils? HA!

Track times alone are not an indication of handling well. Most all reviews I see for various trim Corvettes are its fast and has lots of grip but not pleasing to drive because of its unrefined handling characteristics.

You're playing a funny game here. When presented with emperical evidence (fast lap times) that doesn't agree with your preconceived notions, you dismiss it with statements like this. You're all about "emperical evidence" when it's negative SUBJECTIVE impressions ("unrefined"), though!


The springs are the simplest, dumbest part of the suspension. They provide a restoring force pretty much linear with deflection. You can design in progressive rates with either coils or with leafs, but usually straight rates are preferred for serious performance cars.

Handling feel is going to be VASTLY more affected by all the factors I mentioned in my last post than by whether the springs are coils or leafs.

Being that is the only car with that suspension setup I have no other car to form a different opinion of transverse leaf springs.

Extrapolating a curve based on a single point?

It is worth noting that while giant sticky front tires provide more grip, they can hurt handling feel quite a lot. Both the Corvette and Viper suffer from this.

But in the Viper's case it can't be due to leaf springs, now can it?

Actually I happen to have a new Viper/C6 ZR1 comparison test in front of me (Feb Car and Driver). Similar power/weight, ZR1 2 seconds(!) faster at Laguna Seca. AND they liked the Corvette's handling feel a lot better.

Is the difference down to leafs vs. coils? Of course not. Tires and dampers? More likely...

[vtmike]

Originally Posted by LSxJunkie

I guess you don't know what enjoyable means.

Is this still an indictment of transverse leaf springs or have you dropped that argument and just started going after the Corvette's handling in general?

The complaint of the leaf springs stems from the handling of the Corvette. I understand there are more things at play than the leaf spring set up alone. I'll admit I can not conclusively say the leaf spring plays a roll just as much as you can't make the claim that it doesn't. Maybe the spring rate is a limitation of the leaf spring? I don't know.

I want to like the Corvette. I want the US to have a world class performance/supercar. I don't feel the c6 is that car and many people share that opinion.

I just fear the c7 is going to be the same way with what has stayed in the design. At least the interior and seats have improved.

It's just disappointing when considering what Chevrolet can do with the zl1 and 1le handling in such a heavy car. Descriptors of them are well composed, well controlled, a track delight. Not brute and handful. Which happen to have coilover setups. Whether or not it is a factor. I want to see people describe the Corvette as well controlled, and well composed.

Not even going to go into the ohv engine that's already been debated too.

I would love to buy a Corvette that's well composed and has an engine similar to ford's 5.0 v8.

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