C3 high speed stability?
Thread Starter
Team Owner
Joined: Jun 2004
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From: Smile, it's just the internet.
C3 high speed stability?
I have no experience with the C3 in this area and I'm well aware that some older cars can have a problem with general stability and lift at high speeds.
How does the stock 68 C3 handle triple digit speeds? How about after a mod like the Street & Slalom kit from VB&P and W-rated 17" tires? My other cars tend to squat at high speeds and remain very stable. I hate to find out the oposite is true for the '68 just before the front end lifts and I die... With the TKO in there, 150+ shouldn't be hard to see if the car can take it.
How does the stock 68 C3 handle triple digit speeds? How about after a mod like the Street & Slalom kit from VB&P and W-rated 17" tires? My other cars tend to squat at high speeds and remain very stable. I hate to find out the oposite is true for the '68 just before the front end lifts and I die... With the TKO in there, 150+ shouldn't be hard to see if the car can take it.
Melting Slicks
Joined: Feb 2004
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From: largo florida
http://forums.corvetteforum.com/showthread.php?t=170473
I think the body is all stock except for a larger chin spoiler. It hit top speeds of 212 on the strait aways. I wouldnt worry about the aerodynamics so much as I would worry about the 35 year old suspension and brakes. You should defiantely go through things like that to make sure everything is up to par before you start hitting dangerous speeds. Oh yeah, one more thing about the aerodynamics of a c3... a 68 l88 has a drag coefficient of .360 and a frontal area of 19.5 sq. ft. A viper gts has a drag coefficient of .350 and a frontal area of 20.50 sq. ft. From my limited understanding of vehicle aerodynamics, it appears that viper has slightly worse aerodynamics because of its larger frontal area.
I think the body is all stock except for a larger chin spoiler. It hit top speeds of 212 on the strait aways. I wouldnt worry about the aerodynamics so much as I would worry about the 35 year old suspension and brakes. You should defiantely go through things like that to make sure everything is up to par before you start hitting dangerous speeds. Oh yeah, one more thing about the aerodynamics of a c3... a 68 l88 has a drag coefficient of .360 and a frontal area of 19.5 sq. ft. A viper gts has a drag coefficient of .350 and a frontal area of 20.50 sq. ft. From my limited understanding of vehicle aerodynamics, it appears that viper has slightly worse aerodynamics because of its larger frontal area.
Last edited by lostpatrolman; Jul 22, 2004 at 01:41 PM.
Safety Car
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From: The reason time exists is so everything doesn't happen at once
I've had my 69 SB Coupe up to about 125mph...once, just to see what it could do. The car was fairly stable as far as front end lift, but I don't think I'd make a habit of triple digits.
Thread Starter
Team Owner
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From: Smile, it's just the internet.
That chin spoiler is only 3" from the ground. Not a fair comparison to stock... It forces at LEAST half the air my car would run OVER to the side or into & over the hood. With the big gap in the back, you'd be looking at a huge low pressure area on that LeMans car. I can see it being stable at higher speeds. Not so sure about the early C3's in stock form. Even the later ones had a lower nose that scooped air up over the car instead of the veritable funnel on the chrome cars...
Safety Car
Joined: Apr 2004
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From: WAY DEEP INSIDE AMERICO,YES YOU LIVE HERE TO!! TX
I used to think my car was unstable at high speeds.
i could even hydroplain at low speeds, in the slight rain.
I used VBP underneath my ride with p275/40 up front
and 315/35 in the rear. anything over 100 is like driving
a slot car for me. Im sure my tires have a lot to do with
stability and traction. In stock form, going that fast with
someone else driving, I would poopie my pants. Use vbp
before you go high flying, and a good set tires
i could even hydroplain at low speeds, in the slight rain.
I used VBP underneath my ride with p275/40 up front
and 315/35 in the rear. anything over 100 is like driving
a slot car for me. Im sure my tires have a lot to do with
stability and traction. In stock form, going that fast with
someone else driving, I would poopie my pants. Use vbp
before you go high flying, and a good set tires
Melting Slicks
Joined: Feb 2004
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From: largo florida
The chin spoiler is atleast 5 inches from the ground, not 3. look at the chin highth compared to the tire sidewall. Lowering the front would drastically help a chrome bumper c3, they can be safely lowered almost 2 inches, which it appears the lemans one was not lowered. I dont get what you mean by "the big gap in the back" The rear highth appears to be stock also.
Edit:
As you see, the highth of the chin spoiler is deceptive, both green lines are exactly the same size. No way that distance is only 3 inches, seems to be more like 6
Edit:
As you see, the highth of the chin spoiler is deceptive, both green lines are exactly the same size. No way that distance is only 3 inches, seems to be more like 6
Last edited by lostpatrolman; Jul 22, 2004 at 02:21 PM.
Team Owner
Joined: Jul 1999
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From: Orange Park Florida
Meg there is right, I have had 275/40/17 Z rated on my car for nearly ten years now, '92 vette wheels....and now the Nitto 275/50/17 in rear and 255 up front, years ago I also did a VBP 460 front spring, and plastic rear, KYB shocks.....obviously I rebuilt everything elsealso....
car is VERY stable at 150, but I am not....lets just say it has far more GO than I have NUTS.....
GENE
car is VERY stable at 150, but I am not....lets just say it has far more GO than I have NUTS.....
GENE
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Burning Brakes
Joined: Jun 2000
Posts: 892
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From: GA
Man.. you guys are brave. I would never want to sustain over 110 mph for any period of time. My car lifts so bad I can hardly see over the fenders (exaggeration.. but you get my point) 
Ask Redvetracr... he hits this speed on occassion...
Ask Redvetracr... he hits this speed on occassion...
Drifting
Joined: Nov 2003
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From: chicago IL
We got our vette up to 90-100 (not excatly sure b/c speedo gears were messed up and slipping), and this was with the stock shot rear spring, stock front springs, and crappy futura tires, and it felt pretty stable to me. I wonder how fast we can get it go with all the suspension, steering, body, and tire/wheel mods that we have 
by the way its a 79 L-48
by the way its a 79 L-48
Thread Starter
Team Owner
Joined: Jun 2004
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From: Smile, it's just the internet.
3 or 5 inchs...makes little difference compared to the 12"+ height of the chrome funneling air under the car. The "big gap" is the difference in height between he front and rear. There is a vacuum created at the rear of the car and the open space under the tail accentuates that some and pulls air out from under the car faster than it can get in under that chin, thereby creating a low pressure area under the car, which forces it against the road. That's overly simplfied, but you get the idea. Take a look at the back of a NASCAR or outlaw and you'll see huge (comparitively) openings in the tail and road-scraping spoilers up front and along the sides.
Team Owner
Joined: Feb 1999
Posts: 34,453
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From: Republic of Texas
Not sure how my '68 wil ride w/ the VB&P suspesnion kit compared to my C4 Vert, but I had my C4 wup to 165mph with a stock suspenion and it was solid as a rock. The C4 sits much lower but the tire sizes are similar.
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
I read some old interviews with Duntov where he stated front end lift becomes a serious problem over 150mph on the early C3 body. Marketing wanted a big rear spoiler but Duntov got it removed. It would have created tons of downforce at the rear and lifted the front, he said. Duntov also had a play car back in the early 70's with either a L88 or ZL1, I forget. One thing he was saying was the hood breaks off the car at 200mph unless you duck tape all the seams.
Duntov hated the C2 body. He called it "the worlds worst airplane" as the body shape acted as a wing lifing the car at speed. That may be, but the C2 still has the looks, though.
Duntov hated the C2 body. He called it "the worlds worst airplane" as the body shape acted as a wing lifing the car at speed. That may be, but the C2 still has the looks, though.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
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From: Chattanooga TN
I think I read somewhere that Zora was very happy with the C3 compared to the C2 as far as high-speed stability. The body shape, and particularly front end was much better aerodynamically.
Safety Car
Joined: Apr 2004
Posts: 3,997
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From: WAY DEEP INSIDE AMERICO,YES YOU LIVE HERE TO!! TX
Originally Posted by mrvette
Meg there is right, I have had 275/40/17 Z rated on my car for nearly ten years now, '92 vette wheels....and now the Nitto 275/50/17 in rear and 255 up front, years ago I also did a VBP 460 front spring, and plastic rear, KYB shocks.....obviously I rebuilt everything elsealso....
car is VERY stable at 150, but I am not....lets just say it has far more GO than I have NUTS.....
GENE
car is VERY stable at 150, but I am not....lets just say it has far more GO than I have NUTS.....
GENE
YOU have to be 
to play like thaton public roads. Not saying i never done it, but it only takes
one time to panic because of someone else in you way.
then its (LIGHTS OUT)
Le Mans Master
Joined: Jan 2001
Posts: 6,938
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From: San Diego CA
It's funny becuase that chin spoiler actually lifted my front end on my old 77 much like a wing. I had the 78 pace car kit on my old 77 and at 125mph my buddy next to me looked over and my front tires were lifting off the ground. It wasn't like I was oblivious to this as my steering input resulted in no course correction. Sufice to say I never went to that speed again.
Melting Slicks
Joined: Feb 2004
Posts: 2,435
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From: largo florida
Originally Posted by CGGorman
3 or 5 inchs...makes little difference compared to the 12"+ height of the chrome funneling air under the car. The "big gap" is the difference in height between he front and rear. There is a vacuum created at the rear of the car and the open space under the tail accentuates that some and pulls air out from under the car faster than it can get in under that chin, thereby creating a low pressure area under the car, which forces it against the road. That's overly simplfied, but you get the idea. Take a look at the back of a NASCAR or outlaw and you'll see huge (comparitively) openings in the tail and road-scraping spoilers up front and along the sides.
Thread Starter
Team Owner
Joined: Jun 2004
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From: Smile, it's just the internet.
My dad used to have a 66 that lifted at less than 160. I was told the story by the guy driving when it happened, my godfather. He lifted off the throttle and let it coast after he realized what was happening. He said he had no steering control for over half a mile after he let off and for at least an 1/8 before. He said the car swerving, using both lanes of the highway under. They were lucky.
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
Meg, you see, it was about 4-5 years ago here in a 3.5 mile bridge here in Jacksonville Fl.....known as the Buckman, it was newish completed to 4 lanes each way in '97 when I moved here, and about 930 pm one evening a ricer fly by and scratch challenge did not go unanswered, so I hit 150 with the top and windows down, blew my glasses off, glad the old steering was on the car then, as wheel input was a bit flakey as I was grabbing for my glasses and lifting the gas also....
I know from the feel of the car with the rack in it now, it's more than capable of brown staining most anyone, especially with top and windows down....
I hate to appear smug, but in fact, doing 120+ in a coupe is nothing, do it with top and windows down....it's entirely another horse.....
GENE
I know from the feel of the car with the rack in it now, it's more than capable of brown staining most anyone, especially with top and windows down....
I hate to appear smug, but in fact, doing 120+ in a coupe is nothing, do it with top and windows down....it's entirely another horse.....
GENE