Z ROADSTER

How many times have you seen a late model f-body convertible driving down the road with what appears to be a pregnant top blown up into a large bubble ?
And unless someone tells you about it , you never know how silly you look in your vert with the huge bubble bulging up from the soft flexable & stretched top .

Blackbirdws6

iTrader: (7)

my top is down 95% of the time when I drive so shouldn't have much issue

-Brian

Black_97'Z

I'm sure my top does that, there's no way that it still holds its shape after 11 years. Hopefully by next spring it will be replaced.

munecorey

iTrader: (2)

how bad does it look? mine probably does that too! does anybody have pictures?

z28bryan02

Its bad, and looks really dum

00cls1camaross

iTrader: (10)

mine too, how do we rid ourselves of this problem?

Xsta Z 28

iTrader: (2)

Don't drive with the windows down and top up . . . then your top doesn't blow up.

Simple solution:

Top down, windows down . .

Top up, windows up . . . you have AC for a reason . . .

Z ROADSTER

Wrong ! ! I just saw a Trans Am vert going down the interstate at about 65-70 MPH and his top was up with windows up & it had this huge bubble in the middle of the top .

Black_97'Z

The top still bubbles up even with the windows up. It's the low pressure, fast moving air over the top of the car that causes the top to bubble. With the windows up it will cause more of a pressure difference, which could cause the bubble to become larger.

Z ROADSTER

I agree . I really don't think driving with the top up & the windows down make much difference either but thats pure speculation on my part .

Jordan S.

iTrader: (17)

It seems like everytime I see a vert around here the top of it is blown up like that.

ur jlus

iTrader: (3)

I don't have that problem and I firmly believe that the top up windows closed at freeway speeds is what has kept me from the bubble top. When I was looking for my vert one of the cars I looked at had an owner who told me this. BTW I've had it for about four years and 65,xxx miles. Just my .02.

00cls1camaross

iTrader: (10)

how do we fix this, do they make a black vinyl

Black_97'Z

It's simple science. With the windows up or down, the air pressure inside the car is greater than the pressure of the air passing around and over the car. The faster you go, the more the pressure around the car drops. Low pressure above the convertible top, with higher pressure below the top will cause it to bubble. It's the same principle that lets airplanes fly. Low pressure fast moving air flowing over the top of the wing, with higher pressure slow moving air flowing under the wing causes lift. I think it's Bernouli's Principle........

In F-body's the layer of canvas (unless you have a white top, then it's vinyl) is attached to the frame bars that run across the top. A short strip of fabric running from one end of the bar to the other is glued to the underside of the canvas and then to fabric that is around the bar. As the top is pulled up while driving, these glued bonds hold the top in shape, along with the tautness of the material itself. With age the material looses it tautness, the areas between the support bars begin to stretch sooner than the rest of the material. When the glue lets go (from heat, age, and stress) you will get a very small bulge in the top while driving, and that bulge will grow over time. Environmental elements also break down fibers in the top, allowing it to stretch more.

I found on my car that not only has the glue on one of the support bars let go, but that the material around the last support bar (the one before the rear window) has torn away from the bar.

If your vert is a weekend, sunny day vehicle, the bubble may take longer to appear, or might never appear. But if you have been daily driving your car for as long as I have, more than likely you have the bubble.

Black_97'Z

Second to last post....
https://ls1tech.com/forums/convertible-vehicles/409996-how-maintain-your-convertible.html