i've been wodnering this cause i gave it hell one afternoon after work with the ttops out and at about 100 or so i swear the car was going to take flight. I've heard of the back window blowing out is this possiable or myth?

i've had mine up to 120-130 with the tops off, not issues.

I'm pretty sure I remember someone on this board claiming that they or a friend blew the rear hatch glass.

About the 17th post down
https://www.thirdgen.org/techbb2/sho...ps+glass+hatch

just intresting random fact i found out.....

in my 82 ttop car and a few other misc hardtop 3rdgens ive driven, as you go faster the car lifts and starts to get lighter....

but with a convertible car with the top down, it actually gets pushed down... one of my friends with a LT4 vert even told me that at 160+(figured by the RPMs in 6th) his car was on the bumpstops....



just some random info... :lala:

When I'm doing about 80mph I start to get SERIOUS wind noise. Loud enough that I have to talk pretty loudly for passengers to hear me. Seals are good, I just need to find a way to pull them down harder. I've taken the car up to about 110mph with the T's out and I love it. ^_^ Don't know what'll happen to my hatch glass, I hear horror stories so I won't do that again.

Oh, and my T-Tops don't have locks. The old C&C locks busted, and I don't have keys, or even know where to get replacements for them.

I think in any car as you go faster, it starts to get lighter. Isn't that the reasoning behind the spoiler? To help the back wheels better stay on the ground? I know that when I hit a small hill in the road at 30, then hit the same one at 80 you can certainly feel the differance, and the car feels lighter.

Now, if we were really aerodynamic nuts then we'd have underbelly pans that would shield the bottoms of our cars and reduce drag.

That alone would probably increase our top speeds a fair bit if done right. It would also trap heat and make it really hard to work on the car.

the real reasoning for the spoilers and wings on are car are looks.. pure and simple... but im sure they have some effect, esp at high speed.

as for the hill thing, the momentum is whats causing you to lift in that case. its like jumping a bike on a ramp.. go slow and you fall off the back of the ramp.. go fast and you jump past it..

with aero lift, on flat smooth ground the car gets lighter.. or heavier...

yea.. lol... i think only a very few people on here are (im not one of them)

i do know that the 3rdgen firebird has one of the best aerodynamic drag COs of any production car... they use them im some forms of salt flats racing where you have to use a production body...


a friend of mine showed me a mint pontiac sales catalog from the 80s... above the firebird was a pic of a 320mph salt flat firebird....

Your car floats at high speeds for the following reasons. You car is in essence a wing shaped object. The undercarrage is flat and the top is curved. Air travels under your car faster than it goes over. It has less distance to travel. You create higher pressure under your car and less air pressure over the top. The result is lift. Spoilers are functional as well as front air dams, windshields and etc. They apply more force to parts of the car that want to lift. More force makes it harder to lift the car. That is why most mustangs are limited to 155 (I think), not because of the tires but because the car becomes unstable and the downforce characteristics are no longer effective because the car is creating more liftting force than downforce. Now you know anbd knowing is half the battle.

along thoes same lines comes my vert vs coupe theory..

with a coupe the air curves along the back glass... creating low pressure behind it and lifting the rear of the car......

with a vert, its all flat there.. so its kinda turbulent of course behind the windshiled, but after that, its all flat with just the spoiler lip sticking up.

You mean high pressure. There is always a higher air pressure on the top of your car than the bottom. Always. You are feeling the rear lft because of what I mentioned avove still. Not all things that are smoth flow better through air. At certain speeds rigdes in a surface can actualy increase the streamline effect on an onject because of what is know as Eddying Wake. Eddying Wake is turbulence that swirls around and actually helps propell the object it just passed over forward.

a low pressure...or atleast lowER...> like a airplane wing, air has to move faster over the top then under because of the curved surface... plus with the back glass dropping down, the air has to move back in around the area... i would assume all that would cause a low pressure area.....


btw, a great example of Eddying Wake is a golfball...... if you want to type out a example for everyone else... id do it but im about to leave....

Good example, you must be an EngiNERD like me. But yes the air has to travel farther over the top of the car and it does so at a higher velocity than underneith. All of the eddywake experiments that I have witnessed all delt with pool table size ***** of equal wieght and size. Some smooth and some with ridges. Put the two of them on a balance and flow air over them and watch what happens. It is pretty cool and you wouldn't expect to see the results that you do. The one with ridges is actually propeled toward the wind force and the smooth one is pushed out. Now on the other hand, the opposite occurs in a highly viscous fluid and or medium where surface area dominates. Wow were nerds.

Hehe, I was just going to mention that the reason golf ***** have dimples is to make them go further.

I don't know all the aerodynamic principles though.

Yup you are correct, and if you put enough back spin on it it too will actually create lift and fly until it slows down and falls. Pretty cool if you ask me.

88 mph

Nope, that alone would make your car "float" at a lower speed because of the high pressure air under there.
Do a google on Bernoulli's principle

The undercarrage of the third gen is about as flat as you'd want it, not a whole lot of drag but not soo smooth that it creates a very high pressure area.

To improve your air flow with the T Tops out try proping your hatch up about 2-3". I use my car cover (in its bag) sitting on the T tops when strapped in the trunk, and a bungee cord holding the hatch down on the cover. It greatly improved my gas mileage when going on long trips with the tops out.

wow,
my car is totally stable at 100+ mph speeds, with stock suspension it was planted, go over bridges with bad struts and the car didnt even move, impressive, i now have sport line springs and kyb shocks/struts. the car is totally stable at high speeds, i can literally cruice at 100-105mph like nuthing, ive gone 120-130 and its smooth as all get out. i dont see how some of u guys claim ur car lifts and stuff at high speed, are ur suspension shot to ****?

I'm going to go ahead and take all that back, must have been high on life or somthing, and not thought about what I was saying

id say the suspension has a lot to do with the lift at high speeds, ur sayin if a car has worn out struts/shocks and springs that its gonna hold the road as nice at 110mph as a car with a lowered suspension, nice struts and shocks?

Loose shocks and springs will contribute to a "lifting feeling" The body is creating lift and the wheels aren't. You are in a way lifting the car and leaving the wheels behind. Stiffer springs and shocks need more lifting force to extend them to their limits than the stock pieces. The lower your car the less amount of air can travel underneither it. That is why nascars literally have no space under them. The only reason indy cars do is to allow that air to pass over there front and rear wings. Now as for cornering that is momentum shifting anf nothing to do with lift.

We went 155mph without the t-tops in my brothers 96 T/A.
We were on the way to the store when we decided to test the car to see how much topend was lost with 4.10 gears and a 6 speed.