milesnstylin

does a c3 experience much aerodynamic lift above 130 mph ? do you use front scoops and rear wings or what

Metalhead140

https://www.corvetteforum.com/forums...ve-120mph.html

mrvette

First, use a GPS to prove your speed, the tachs and the speedos are prone to over indicate above 80 mph and above ~3500 rpm, I have proven both to be liars via testing with generators, scopes and GPS......

Red86Z51

Years ago I learned about C3 front end lift. The stupid way. I ran my '68 427/390 flat out on a long stretch of freshly repaved IN-2. At just a little over 145 the front started to float. It scared the hell out of me. It was the LAST time I ever did that in ANY car.

How much lift did I experience? I don't know....I wasn't about to stick my head outside to see.

Easy Mike

Yes. The nose comes up and the steering gets light.

Neither. I lift my foot and let it come back to earth.

.

Jebbysan

Probably the easiest thing you can do to alleviate front end lift is to lower the front end of the car.......
My 69' 427/400 would lift at 120 mph......It sat too high in the front due to new Moog springs.......I cut a coil out and lowered the car about 1 1/2" and it did not lift at 120 anymore......it lifted at 135 mph LOL!
But that would be the first thing to do.

Jebby

vince vette 2

I can say this, not having an air dam definitely allows it to get light.

Bought my '80 L82 new and didn't notice the dealer never put the "rubber" air dam extension on. The reason is I suspect unloading the car they banged the front end which bent the metal tang intended to keep the air dam section of the polyurethane front bumper from getting bang on a light hit. The tang bent the bottom of the poly bumper back and as the rubber extension was supposed to mount to that it couldn't. Rather then fix it, they just sold it as is. A few years later I was on my way home about 2 AM, from a night of writing software for a college course - not from a bar - it's the truth. I was on I-490 heading west out of Rochester when an RX-7 passed me. Couldn't let that stand. So I rolled it up to get on his tail. I was doing about 110 based on the speedo (and before someone says an 80 had the 85 mph speedo note that I had a reduction gear on the speedo cable to so the kph became mph). I didn't want to pass him, just wanted to show him I could stay with him and then some. All was fine until we approached a car doing a reasonable speed ahead in the right lane. He shifted to the left lane and I saw the 55 mph cruiser about 200 feet ahead. Normally at say 60 mph it would have taken about about 20 to 30 seconds to close that gap. I guess in my head I was thinking as I was double normal speed I've got 10 seconds to react. In reality, my closing speed was more like 50 mph and I had less than 3 seconds. Of course I glanced into the mirror to make sure the left lane was clear, as if at 110 I had to worry about being passed. When I looked forward it was an OMG sight. I cut the wheel left and pressed the brakes, not to the floor since I knew that would likely spin it. It didn't matter. The car started left and then just kept going that way to where I was sideways to my direction of travel. to the left lane. I had cranked the wheel right but it had no effect until I was sideways. Then it responded and when it aligned to the highway, now in the desired left lane, I put the wheel straight and the was back to normal driving. I have no idea what direction I was pointing when I passed the guy in the right lane. But it must have been and interesting site for him. I suspect that the front was so light without the full air dam that any quick turn would just initiate movement but then let it just lifted more and left virtually no weight on the front tires.

Eventually I did get the rubber extension, fixed the deformed bumper and installed the extension. That 2 inches of additional drop made a noticeable difference on handling at high speeds. You didn't note what year C3 you have. But there are a lot of aero differences from the 68 to the 80/82. It always seemed to me the earlier models likely would have more of an issue with front lift as opposed to the last models - but that's guess and I'm open to education there. But knowing what I experienced, if earlier models were not as good as the later ones in this area, I can see potential issues. if you look at the avatar on my post, that is the car in the story and it does not have the extension on it at that time. But even without it, it would seem to have more material to keep air from getting under the car than the earlier models. Again, just guessing here, so if I'm wrong I am open to being told so.

leadfoot4

I haven't been on 490, west of Rochester, in quite a while, at least not past where the 531 expressway branches off to the right. However, I used to go out that way 3-4 times a year, during the summers, when I was helping a couple of friends who lived out that way, and owned a drag car. I never thought that 490 was a good road to be "top ending", as the pavement isn't all that good, and there were a few "undulations" in the road, that could help you get "light". Glad you survived!

fishslayer143

my 81 has Ground Effects Pkg front, rear and sides, on it.. its not just for looks, it actually does put down force on it front and rear With 525HP ,I have had it over 150 mph a few times with no issues except not enough good road to let it all the way loose .. That and my tires are not rated for higher speeds .. and if you tell the Hiway Patrol, I'll deny it...

7t9l82

I had a 68 L-88 back in the mid 70's and I was known to run the dulles access road late at night outside D.C for top end runs. I can say lowering the front end made that car vastly better however, I believe there is absolutely no comparison between that car and my 79 with the pace car spoilers also with a lowered front end.
the 79 at 100 just seems planted and truthfully feels more stable at 100 then at 70..now there other factors like springs and QA-1 shocks so it's hard to say it's all spoilers.

vince vette 2

Not sure of the timing of your drives on 490 west of Rochester. The incident I mentioned occurred in 83/84. Back then NY still had decent roads. We always griped about the extra 25 to 30 cents a gallon we paid for gas vs. states like PA, which even then was consistently rated as having the worst roads in the country (anyone crossing the north to south on Rt 15 back then could attest to the truth of it). But at least that extra gas tax went into top notch roads. Today PA gas is the same price as NY. But Rt 15 through PA, other than when it's going through urban areas, is a far better than it was in the 80''s. In contrast, your description of 490 in NY is spot on today and not limited to that interstate in NY. Today I often drive for miles in the left lane of 390 in the southern tier to avoid the constant kabump, kabump, kabump of the deteriorated right lane.

A10pilot

With the earlier c3s over 100mph, the front end gets very light (stock vehicle). I think the later c3s corrected that with the body work that included the air dam, but I've never driven one of those.

leadfoot4

My reference to the far western sections of 490, was actually based on my experiences primarily in the 70s. A couple of my colleagues from where I worked, lived in the Byron/Bergen area, and one of them had a large barn that they kept the race car in. As previously mentioned, I used to go out there several times a summer, to help with them with the car. I was living on the east side of Rochester, so I used 490 to get out there. Later on, I was transferred to Kodak's Elmgrove Road facility, and travelled 490 daily, through the city, but exited on to the Route 31 extension, to get to the plant.

It's ironic that you mention US Route 15, Although I've lived in the Rochester area for over 60 years, my father was originally from the Wilkes Barre/Scranton area of Pennsylvania. Several times, when I was much younger, we had to travel back to that area, for family gatherings, and we drove most of the way on Route 15. It was absolutely insane, as I used to describe the road as a "horse and buggy trail" carved into the side of the mountains. I used to drive to the Carolinas, fairly regularly, between 1980 and 2001, and of course, had to use Route 15, to go south out of NY. I was both annoyed, and at the same time fascinated, to have to deal with the "OLD" road, yet see how it had been drastically improved, over those years. I understand that even more sections of it have been expanded to 4 lanes, between the New York/Pennsylvania state line and Harrisburg. I'm driving to Washington DC, in a couple of months, so I'll be taking that route, and my curiosity is up, as I'm looking forward to seeing the latest improvements of the road.

I had to drive to Dansville a couple of times, last year, and I agree, 390 has deteriorated quite a bit. It's getting almost as bad as the Lake Ontario State Parkway.....

cv67

Put a deeper air dam on it, fresh bushings/decent shocks it will be just fine.
My A body used to float aroudn 70-80, now can cruise at 100+ all day long without a hint of it.
These old cars didnt drive as bad as some say they did.

vince vette 2

My only car when I moved to PA was the vette. Many trips were had on "old Rt. 15" in it. You had to take advantage of every hill north of Williamsport to snag the passing lane to get ahead of the trucks and mobile homes so you could buy a few minutes of cruising to the next hill and passing lane. Then south of Williams port you had the suicide highway section, two lanes most of the way then a short center lane to allow one side or the other to pass. Seems like PennDoT could never decide which direction of traffic to favor in any section, so they kept switching them. I never new what was coming. But 15 was the only route N-S through central PA. My Rochester born brother-in-law asked me once how to get from Rochester to Gettysburg. He paper and pen ready to go. I told him to get on Mt. Hope Avenue heading south and paused. He wrote it down. Then I said, get off when you see a sign for Gettysburg.

Route much better to Harrisburg now. From the NY-PA line to Harrisburg most choke points are the cities and "enlarged towns- Williamsport, Allenwood, Lewisberg, Shamokin Dam/Selinsgrove. The other choke starts about 20 miles north of Harrisbur when you hit Duncannon, Marysville and the like. But in between all limited access 4 lane. A few miles into PA check out the visitors' center. Really nice facility, beautiful view. Sections in northern PA have a 70 mph limit. Watch for deer - even worse today as there are fewer hunters. Also, just south of Liverpool where PA route 17 intersects they have warning signs that note it is not NY 17 which is much more heavily used. Even though its about 100 miles from the NY border, it seems a lot of people, even truckers, would turn on PA 17 and head tens of miles west without realizing they weren't in NY yet.

Good old Kodak. Paid indirectly for a good chunk of my education at UR. One of my engineers here in PA (a Bucknell guy, but OK otherwise ) spent a summer internship at Elmgrove. Sad demise for sure (probably not his fault though). Back when you were heading out to the Byron/Bergen, in the late 70's did you ever stop at the Mecca Farms strawberry field that was just a couple minutes off the 490 exit to Bergen? The Meccas were family friends and we ran that field for them. Maybe we've met. I grew up in Stafford, so the same basic stomping grounds and also a lot of time working on cars in barns.

leadfoot4

When heading south, out of the Rochester area, I avoid 390, because it goes SO far west before it finally turns and heads southeast. (unfortunately 390 wasn't round some 45 years ago, when my "high school sweetheart" was at the college in Geneseo!) I head out Clover Street, to Honeoye Falls, then go south/east on 15A, to Wayland, and pick up 390 there. I've looked at Google earth, and it seems that 15 is now 4 lanes, all the way to about 20 miles north of Harrisburg, as you mentioned, bur I must have scanned over the small towns where it isn't. I'll have to take a second look.
What I did in the past, was go to Williamsport, then swing east/southeast on I180, and follow that through/around Williamsport. After crossing under I80, 180 becomes PA147, then narrows. Although only 2 lanes, it's a good, relatively flat road, and I'd follow it to Northumberland, PA, then jump back over to 15 for a while. I'd then hop over to 22/322, and follow that to pick up I81, for a couple of miles, then back to 15 and on into Maryland.

I think the thing with the alternate passing lanes, on 15, was defined by whichever direction was going uphill. It gave the automobile traffic an opportunity to get past the trucks/busses, as they were supposed to stay in the right hand lane.

Yes, the failure of EK was tragic, to say the least. Problem was, about 90% of their "eggs" were in the basket of film sales, film processing, and printing of pictures. And since they had refined those processes so deftly, they literally had a license to print money. Take the film sales away, as digital photography did, and the income stream dried up. It's extremely ironic that one of EK's own R&D teams invented the digital format....but if they hadn't, someone else would have.

vince vette 2

15 is 4 lanes through most of the towns, it's just dealing with the traffic lights. 147 is scenic. I've run that route too sometimes. Enjoy the trip.

427Hotrod

I think dialing in some rake helps a lot. Many folks run same size tires front and back and run around with the butt lower than the front. No wonder it's going to get air under it. Anything you can do to vent air from under hood will help also.

Not a C3...but C2's have a bad rep also. Mine drives fine at high speed. Not Lambo fine or C-7 fine I'm sure...but no terrible issues either. It runs low 160's MPH in 1/4 mile.....the pics is at 177 MPH at a half mile event and it also managed 200 MPH in the TX mile. It starts with a pretty big rake to it. For those runs I use extensions on hood latches to vent trapped air. Can't swear it helps because I haven't tried back to back testing...just always did it at the track. I added a spoiler to give a little added insurance before the real high speed runs. Can't swear it helped either..but probably didn't hurt. With the HP it has...the front wants to rise as I apply power...so I'm sure it could help with some even stouter shock control or limiters.


Now that poor 'ole softtop is another matter! LOL

JIM

vince vette 2

From 427HR "Now that poor 'ole softtop is another matter! LOL"

I thought it was fashion statement

wb003

My 1970 L46 is solid at 90 mph, and was still good at 115. With the 6K redline, the 3.55 rearend and M21, my top end is only 134...