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post #1 of 13 (permalink) Old 03-08-2008, 09:31 AM Thread Starter
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Strange vibration with rear windows down!

I recently bought a 2005 Cobalt LS Sedan.
I found that when driving on the highway and both rear windows are rolled down a very strange vibration is felt. It's kind of like a "sonic airwave disruption" inside the car, for lack of a better description! It will actually hurt your ears!
Roll the back windows up and the vibration is gone.
BTW, This isnít a problem with the front windows down.

Now with that said, I have the oem tires - Conti's Contact AS.
Well actually I have 3 of them and an odd replacement tire, the brand is Lexington.
The replacement is the correct size and very similar tread pattern but the shoulder has a more square edge compared to the Contiís rounded edge.
Anyone think this is the source of the strange vibration?
And why is it only noticeable when the rear windows are down?
Iím thinking about putting that tire on the front and see what happens.

And one last thing on the tires, I've read on this forum and others that the oem Conti's aren't the greatest tire for the Cobalt.
Any recommendations for a good all-season performance tire that can handle snow and ice well?
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post #2 of 13 (permalink) Old 03-08-2008, 11:24 AM
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There is nothing wrong......

It is the wind/pressure etc. It has nothing to do with the vehicle mechanicals. Most vehicles will do it given the right speed, air flow and certain windows down at the right amount. If you have to have the rears down, open a front until it stops...

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post #3 of 13 (permalink) Old 03-08-2008, 11:24 AM
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Hahaha! yup it happens in the coupes too! I'm fairly sure it's the aerodynamics of the cars. I found it happens at about 80mph. In my car if you pull the seat belt tight it will usually stop or not be as bad.

As for tires, I recommend falken Ziex ZE-512. I have them and I love them. I drive in the snow and they do great.

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post #4 of 13 (permalink) Old 03-08-2008, 11:50 AM
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haha the strange thing about this phenomena is that it's a good sign if your car would be good for subs. Somehow its a sign of how much air the cars cockpit can hold or something.

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post #5 of 13 (permalink) Old 03-08-2008, 12:41 PM
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yea it is the aerodynamics some cars have worse sound then others i remember my moms impala had it horribly and would like drone your ears out

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post #6 of 13 (permalink) Old 03-08-2008, 12:53 PM Thread Starter
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Based on these replies, if it's not the tires then it's the cars shape or light weight or something. Maybe the air entering the car is slightly lifting the car up in the rear?
(crazy thought but maybe)

I've owned close to 50 vehicles and I never experienced that condition with any of them.

It is like you have your 1000 watt stereo cranked up with no music, just an ear popping hum going through the subs, seems like the windows will pop out if you let it go on long enough!
Something's not right!

I'll still swap the tires front to rear to see if that makes a difference. (once it stops pouring)

I have had vibration problems in the past on a pickup. It was from new (but cheap used car dealer installed) tires. Had the tires replaced with name brands and the vibration was gone!

Thanks for the replies!
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post #7 of 13 (permalink) Old 03-08-2008, 10:11 PM
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MYTHBUSTERS lol didnt do this but said what could be causing this... with the windows down the back of the car works like a parachute, catching air. That would do it for the vibrations and your gas mileage.

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post #8 of 13 (permalink) Old 03-09-2008, 11:59 AM
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That used to happen in the jetta I had. Anytime I would roll the back windows down, usually for my dogs, then get up to highway speed it would start. I'm sure its due to the air coming into both sides of the vehicle through the rear windows like others have said, either changing pressure levels or just creating drag. You'll have to roll them all down or drive slower lol
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post #9 of 13 (permalink) Old 03-28-2008, 10:16 AM
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GTO1 is absolutely correct! It is very common on 4 dr vehicles of any type or make. SUV's seem to be the worst. Do as GTO 1 has suggested and it will be tolerable. Good Luck.
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post #10 of 13 (permalink) Old 03-28-2008, 11:07 AM
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I know what you're saying,but it honestly doesn't bother me.Now I could understand if the weather stripping was off and you hear that wind crackling sound,now thats annoying.:PI had that problem on my old junk vehicle and for the first month it was annoying then I just ignored it by playing the radio.

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