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TheMonk
Dodge Dakota
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9/13/2004
09:22:18
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 Subject: Tonneau cover is like a balloon
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Message:
I just installed my new Extang Black Max cover on my 04 Sport QC 4X4 and like the looks, but have a problem that I was hoping you guys could help with. When I get up to 50+ mph, air gets into the bed of the truck and the cover "balloons" up instead of the cover pushing down on the support bars. I have the cover frame nice and tight to the bed of the truck. I looked between the cab and the front of the bed (2inch gap) and noticed square holes in the front of the bed. What are these? Do these allow air to get into the bed of the truck or is air coming from the cover not sealing correctly? I should mention that the "ballooning" effect is happening more towards the front of the bed and very little towards the tailgate. That makes me believe the air is getting in from the front, not the back or sides.
Last resort: I get in the bed, my wife shuts me in, drives on the highway and I find where the air is coming from. If I do this, I may never get out or she will take it off-roading with me in the bed.
Thanks in advance.
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99bludak
Dodge Dakota
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9/13/2004
09:55:03
| RE: Tonneau cover is like a balloon
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Message:
This is not happening because of air getting into the bed. It is happening because of the bernouli effect. This is the principle that allows airplanes to fly. Ever notice that a convertible top going down the highway also balloons like that? Same principle. The air moving over the top of the tonneau creates lower pressure on top of the cover than inside the bed. Thus the air inside the bed is actually pushing up on the cover. It is happening only at the front of the bed because the air is hitting the back portion and pushing it down rather than flowing over it and allowing it to lift. So, unfortunately not much can be done about that with a soft cover. A hard cover is the solution. Hope that helps.
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Jeff
GenIII
 
9/13/2004
15:07:18
| RE: Tonneau cover is like a balloon
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Message:
well said.
but i think i can safely speak for all of us here when i say that we'd like you to try the offraoding in the bed idea, and take video so we can watch you bounce around.
:)
:)
Jeff
'99 3.9 clubcab
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99bludak
Dodge Dakota
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9/13/2004
15:13:31
| RE: Tonneau cover is like a balloon
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Message:
Watch out though...the wife may like that "thunk" that you make when she takes a corner hard, waaaayyyy too much!!
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TheMonk
Dodge Dakota
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9/13/2004
15:19:00
| RE: Tonneau cover is like a balloon
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Message:
Thanks for the response. Maybe I should have paid attention in Physics instead of staring at the girls.
It would be pretty funny watching someone in the bed while off-roading.....not me....that was just a joke, I wouldn't wish that on my worst enemy.
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Rue
Dodge Dakota
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9/13/2004
15:55:13
| RE: Tonneau cover is like a balloon
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Message:
My family owns a peach and apple orchard, and growing up I would work with my cousins. Well one year we were out working and my one cousin was driving, I was in the passenger side, and his brother was in the bed, sitting close to the tailgate which was down. My cousin who was driving thought it would be funny to drive across the rows of trees which made the ride rather bumpy. He goes over the first row, and my cousin in the back flies up in the air, looking through the mirror he must have come about two feet off the bed, he comes down hits the tailgate on his back with his feet straight up in the air, hits and then bounces back in the air before falling to the ground. He laid there for about 5 min. while his brother and I laughed our asses off. Just thought it kind of goes with the conversation, and maybe could get a few laughs. I guess that is what happens when you give a bunch of 14 and 15-year lots of land and plenty of vehicles to play with.
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Hammerdak
Dodge Dakota
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9/14/2004
21:27:44
| RE: Tonneau cover is like a balloon
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Message:
It's not a perfect solution by any means, but if the tailgate is down the air pressure in the bed won't be able to build up and the cover will stay flat.
Or you can try leaving the front edge of the cover open a couple of inches to release the pressure.
Just remember to get a hard cover after the soft one gets knifed by some curious car molester.
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Justi
Dodge Dakota
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9/14/2004
22:57:16
| RE: Tonneau cover is like a balloon
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Message:
I have a Torza tonneau cover (soft cover) on my '03 4x4 Quad Cab and do NOT have this problem. I had another soft cover (forget the manufacturer) on a '94 F150 and did NOT have that problem. I'm not saying the pressure theory isn't true but I AM SAYING that the problem is not experienced by all soft tonneaus. I'd actually be willing to say that it does NOT happen with most of em. You either have an ill fitted cover, a poorly designed frame (which I doubt as you have a name brand cover), you have a defective unit, or most likely, it's not installed properly. I can't tell you what exactly might be wrong, but I can tell you that it's not hard cover or bust..
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TheMonk
Dodge Dakota
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9/15/2004
08:57:17
| RE: Tonneau cover is like a balloon
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Message:
I also have owned a soft cover before on my old Tacoma and it didn't do this. However, the cover was made of a more heavy-duty leather or leather-like material. It was noticably heavier. I wonder if the material has something to do with it, along with the air pressure. Tonight I will get in the back and let my wife drive me around. I will be searching for any air leaking in. Seeing that I installed the cover, there may be flaws, many flaws.
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Lurkin
Dodge Dakota
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9/15/2004
09:18:48
| RE: Tonneau cover is like a balloon
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Message:
TheMonk, it also depends on what you mean by "ballooning". The exTang cover on my 02 QC does the following from front to back while at highway speeds:
o I came see the front bow holding up the cover
o The middle bow can't be readily made out due to "ballooning"
o The back bow can be seen as the air flow is pushing the cover down between the back bow and the tailgate
But the cover does not flap in the wind, nor does the middle ballooning make the cover look like a convertible top.
One last thing, are your bows set on the high nubs, or the low nubs? If they are on the low nubs, I could possibly see the cover being perceived to look as though it is ballooning more then it is.
By the way, I've had my cover for over a year now, and it's still looking and working great. I wanted a light and easy to remove cover as I occasionally haul items in the bed that require the cover to be removed or rolled up. Hard covers are not the most convenient way to get what I wanted. Also the eXtang soft cover was cheap! But, locking a soft cover doesn't work quite as well as it does with a hard cover ;-)
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TheMonk
Dodge Dakota
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9/15/2004
09:34:37
| RE: Tonneau cover is like a balloon
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Message:
Lurkin,
My cover doesn't flap in the wind, it just lifts up a little where cover meets the front and middle bows. Sounds very similar to your situation. I do have the bows on the upper setting and I also have all the reversable snaps in the lower position thus making the cover tighter.
I have to say, I bought my cover for the exact same reasons you did. Hard covers are not for me. I am in no way disappointed in the cover, just my other cover didn't do this and was wondering if there was a way to resolve it. Thanks.
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wakely
GenIII
9/15/2004
10:46:49
|  RE: Tonneau cover is like a balloon
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Message:
I did not like the prices of the tonneau covers, so I made my own out of (2) half inch sheets of plywood. I only had to drill 2 holes in the bed (front wall) to secure it. Painted it white to match the truck. I also added a Pop-Lock tailgate lock.
It takes me about 2 minutes to remove it from the truck (comes off in 2 pieces).
The rear section folds over the front section, and the whole cover can be raised for access (hinges at the front of truck bed.
If any one is interested in pictures I can try to take some (I may need help on getting them in email form.
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