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Question about stiffness in the 2013 gt500


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So now that the c7 corvette is out they keep talking about how stiff this thing is and because its so stiff it feels solid when driving and isn't effected as badly as bumps in the road etc. I always thought it was the opposite with stiffness. I thought if the car is too stiff then there is no give so on a road (not track) it will be bumpy as hell and slide around a lot.

 

If this stiffness thing is true shouldn't we all be putting parts like the boss x brace, FRPP strut brace, shelby rear brace, and shelby subframe connectors? Pretty sure all of these things would increase the stiffness of our cars by like 80% or something. But I don't really see people doing all of this stuff. Why is that?

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According to Van@RevanRacing in a post on the SVTP forum: "There is a lot that can be said for what Ford did with the stiffness of the S-197 Chassis." He sells and installs Griggs Racing suspension parts, including their chassis-stiffening components. Even still, Van doesn't seem to be compelled to recommend adding chassis-stiffening parts for our Shelbys.

 

http://www.svtperformance.com/forums/2013-shelby-gt500-413/906845-questions-reguarding-suspension-13-gt500-2.html

 

For whatever that's worth. (As in, I know it's true because I read it on the Internet.)

 

One thing's for sure: Our cars are already porcine, and adding stuff to increase stiffness will make them even more so.

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Porcine is right, I dont want to do too much to make mine a fat ass garage queen.

 

 

Thanks for the vocab lesson I had to google what porcine ment, never heard of that word before lol. Why would making it stiffer make it more pig like or turn it into a garage queen?

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If the ride is too stiff, you won't enjoy driving the car.

If you are only racing ( drag or road track ) then its fine.

If you are cruising, the stiff ride sucks.

 

 

Exactly that is what I thought. So that is why I was wondering why with the new corvette they keep stressing that increasing the stiffness like 500% made it feel more solid and ride better especially thru bumps on the road.

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Exactly that is what I thought. So that is why I was wondering why with the new corvette they keep stressing that increasing the stiffness like 500% made it feel more solid and ride better especially thru bumps on the road.

 

 

The idea is to stiffen the CHASSIS as much as possible and allow the SUSPENSION to do all of the work. You will get more consistency out of a set-up that way.

 

Stiffening the chassis makes the car more reliable and consistant for chassis tuning because you don't have to deal with the 'unknown' factor of chassis flex. If you have a chassis that flexes all over the place, it's hard to get it the handling consistent. The more chassis flex you have, the more inconsistent your set-up will be (to the point of impossible to get right).

 

In "the old days", we used to take a full frame car, remove the body from the frame and weld EVERY seam on the frame, 'box' the frame, etc. etc. all in a effort to make the frame as stiff as possible. Solid body mounts (vs rubbber OEM mounts) were used, 8 and 10 point roll cages were used...All in the name of making the CHASSIS as stiff as possible.

 

Then put a good working suspension under it and you can tune a car to your hearts content.

 

On our dirt cars, we used a SUPER SOFT suspension to allow the car to 'roll' into the corners. I'm not a road racer so I can't comment (with any educated knowledge) on how you set-up a asphalt car (other than tires). They're doing things with asphalt cars these days that we never even THOUGHT about doing in days of old (soft rear shocks for weight transfer/rear bite coming out of corners, one-way valves to compress the rear end under high speed/high spoiler downforce to get the spoiler out of the air (Daytona/Taladega), etc. etc. etc.

 

Shock technology has changed tremendously in the past few years and I've not been in a position to keep up with it.

 

 

Phill

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The idea is to stiffen the CHASSIS as much as possible and allow the SUSPENSION to do all of the work. You will get more consistency out of a set-up that way.

 

Stiffening the chassis makes the car more reliable and consistant for chassis tuning because you don't have to deal with the 'unknown' factor of chassis flex. If you have a chassis that flexes all over the place, it's hard to get it the handling consistent. The more chassis flex you have, the more inconsistent your set-up will be (to the point of impossible to get right).

 

In "the old days", we used to take a full frame car, remove the body from the frame and weld EVERY seam on the frame, 'box' the frame, etc. etc. all in a effort to make the frame as stiff as possible. Solid body mounts (vs rubbber OEM mounts) were used, 8 and 10 point roll cages were used...All in the name of making the CHASSIS as stiff as possible.

 

Then put a good working suspension under it and you can tune a car to your hearts content.

 

On our dirt cars, we used a SUPER SOFT suspension to allow the car to 'roll' into the corners. I'm not a road racer so I can't comment (with any educated knowledge) on how you set-up a asphalt car (other than tires). They're doing things with asphalt cars these days that we never even THOUGHT about doing in days of old (soft rear shocks for weight transfer/rear bite coming out of corners, one-way valves to compress the rear end under high speed/high spoiler downforce to get the spoiler out of the air (Daytona/Taladega), etc. etc. etc.

 

Shock technology has changed tremendously in the past few years and I've not been in a position to keep up with it.

 

 

Phill

 

 

Good info. Thanks.

 

When I was trading in my 2001 Cobra, when the used-car manager was assessing it for a trade value, he asked about mods. I said the only mods to the car were a 5.0 shifter and a set of welded-in Griggs SFCs. He frowned at this, saying, "Just so you know, you need to disclose chassis modifications like this to potential buyers. Otherwise, there could be a liability on your part because it [chassis modifications] changes the crash dynamics of the vehicle."

 

What do you mean?, I asked.

 

(Paraphrasing): "While the rest of the vehicle was designed to absorb an impact, the sub-frame connectors could remain rigid and intact but break at the front mounting point and therefore spear one of the occupants of the vehicle in a severe impact when he or she might have otherwise survived." He said it's not a problem, since I did, in fact, disclose the mod. So I can therefore dismiss liability for the SFC mod for what it is -- which is, in the minds of lawyers, a mod fraught with doom for future occupants of the car and the promise of one third of all damages.

 

But the larger point goes along with what you are saying. Bolting on or welding in bits and pieces doesn't really do much to add tortional rigidity to the car. It could actually be a liability, as the used-car manager pointed out to me. You have to go all-in in terms of chassis stiffening, but when you do, the niceness of the car goes away. Otherwise, it's a waste of time and money and just adds weight to a car that's too heavy as it is.

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When I was trading in my 2001 Cobra, when the used-car manager was assessing it for a trade value, he asked about mods. I said the only mods to the car were a 5.0 shifter and a set of welded-in Griggs SFCs. He frowned at this, saying, "Just so you know, you need to disclose chassis modifications like this to potential buyers. Otherwise, there could be a liability on your part because it [chassis modifications] changes the crash dynamics of the vehicle."

 

 

He's right about "crumple zones" but only partially right about disclosure laws. Disclosure only applies if you KNOW about the mod/problem. If you hadn't told him about and he sold it, HE couldn't be held responsible (or his company) because he/they weren't aware of it.

 

It's the same thing with a house when you go to sell it. LEGALLY, you must disclose any problems or potential problems that could effect the value of the house. If there is a proposed Wal-Mart for the empty lot next door, AND YOU KNOW ABOUT IT, you must disclose it IF it can hurt the future price of the house (which is debateable on either side of the argument).

 

Now, as for your car that you modified....I'm not sure if YOU could be named in a lawsuit because you didn't disclose a car that you sold and it was RE-sold (make sense) but for sure, the guy you sold it to couldn't be held liable (since he did NOT know about it).

 

As for the crumple zones, that is one of the theories regarding the death of Dale Earnhardt. NASCAR had mandated so may bars in the car that it became TOO stiff and all of the energy in the crash was absorbed by his belts (although improperly installed by DE himself) rather than by the chassis. The *only* 'crumple zone" he had was the light sheet metal between his front grille and the frame of the car therefor so much force was put on him that he had a basil skull fracture (base of the skull breaks and is fatal). Ironically, "The Earnhardt Bar" was a bar that NASCAR mandated runs down the middle of the windshield from the halo to the crossbar and would likely have been one of the contributing factors to this death (one of many).

 

So yes, crumple zones are well engineered into a street car and are easily compromised by such things as sub-frame connectors, roll cages, etc. etc. etc. Obviously, the MORE structure you add, the fewer crumple zones you have. All of those crumple zones are designed to ABSORB energy in a crash, rather than you body absorbing it all.

 

 

Fodder for your next game of trivia pursuit,

 

Phill

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Forget that. I think I'm old :(. lol. But no this woman was like at least 50-60s.

 

 

<GASP!> 50 or 60???

 

Sheesh, that's ANCIENT.....

 

 

Phill Pollard - 7/26/55

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What the used-car manager said was definitely news to me. I don't recall reading any legal disclosures from Griggs Racing when I ordered or received the SFCs. So if what you say is true, that if I didn't know about a potential problem, then I wouldn't be liable if, God forbid, a future owner were grievously injured or killed as a result of the installation of the SFCs on that car. Still, one would think that Bruce Griggs's lawyers would be on top of the issue. Maybe there was a disclosure, but I honestly don't recall.

 

Ironically, my motivation for installing the sub-frame connectors in the first place was because of Griggs's claim that it would "add longevity to the car." Admittedly, the car was a garage queen -- I owned it for more than 11 years and it had just under 31,000 miles on it when I traded it for the Shelby. I spent lots of nights last summer creating wish lists, running cost-benefit analyses, etc., trying to figure out how I could make my 2001 Cobra somewhat competitive (on paper) with the 2013 Shelby GT500. (I actually really loved that car. It had the IRS, which liked, and I'm not a drag racer. And the Cobra weighs 410 lbs less than the GT500.) I eventually concluded that the money and time necessary to make my Cobra even remotely competitive with the GT500 was not cost-beneficial. And the warranty on my Cobra had long since expired. I rationalized my decision, saying to myself that "every 10 years or so, a man's got to buy a new car." I thought I would miss the Cobra. I don't.

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