Shuddering with rear window down

WoodyInsight · 10-17-2009, 10:20 PM

Has anyone else found this problem. I was merging onto the highway this morning. I had decided to take my lab with me therefore I had the rear window down as he likes to stick his head out and sniff. As I approached 55 or so the whole car started to vibrate ( I'll call it an earthquake). I mean the seats were shaking and the rear view mirror looked like it would shake off the windshield. There was also a loud thump thump thump noise that was almost deafening. I immediately thought I had a flat but I decided to roll the window up since this was the only change to my normal driving habits and the noise stopped instantly. This "earthquake" was repeated with both rear windows down but only down 1 at a time. I have never experienced anything like this with any other car I have owned? This makes the car impossible to drive with the rear windows down and the front ones up.

Fl_Fyr_Fytr · 10-17-2009, 11:48 PM

Funny, same thing happens to me but instead of the windows, it's when I turn the dial in the middle of the dash. Could swear it was an earthquake

Seriously, is the I2 really that bad?

WoodyInsight · 10-18-2009, 12:12 AM

This is the only negative that I have found with this car after 3000 miles other than I feel it needs a bigger gas tank.

TNQR-TOY · 10-18-2009, 04:25 AM

My 2003 Jaquar does the exact same thing as you described -
That Thumping noise is deafening !

Bummer, if my new Insight does the same thing
I will find out tomorrow

Must be some aero thing happening -
You would think that the Designers would have caught the problem

**waterdog** · 10-18-2009, 03:23 PM

It may be that the I2 is more extreme because it is a light car, but every other car I have owned does exactly the same thing. If I don't at least crack a front window open when a rear window is open, the pounding is deafening.

corey415 · 10-18-2009, 04:51 PM

I believe this is called Helmholtz Resonance. I notice that it happens on the I2 at speeds greater than 50mph.

I have experienced this in other rentals cars that I have driven for work.

crxgator · 10-18-2009, 06:57 PM

im pretty sure this happens to any 4 door car...

nameless00 · 10-18-2009, 08:56 PM

This happens on any 4 door car. Just put down the front opposite window too; it should fix the problem. This is not a design problem, the more aerodynamic your car is the more likely this problem will occur, it's creating a low pressure system inside the cabin.

Urban legends when I was growing up around this effect:

1) It can create a frequency low enough to crack glass, never experience nor tried to replicate it.

2) It can knock you out if exposed to it long enough.

euro sport · 10-19-2009, 11:53 AM

Every 4-door car I'd ever owned did this. I always referred to it as the "Helicopter Effect". As already mentioned, just crack your front windows a bit and the noise will go away.

WoodyInsight · 10-21-2009, 12:06 PM

Thanks, I guess I should have known this but this is the first 4 door car I have owned.