PDA

View Full Version : Moonroof


jim mayo
05-06-2003, 11:59 AM
We just bought a 2003 XC70 to replace a 1999 S80 T6-- our third Volvo. Compared to the S80, the moonroof on the XC70 seems to be very loud when fully opened and at slower speeds, and you get that "harmonic resonance" sound. The S-80 had a pop-up metal wind dam which seemed to solve the problem -- why no similar feature on the XC70? Is there a solution anyone is aware of?
cbob
05-06-2003, 01:55 PM
At low speeds it's pretty freaky.
Crack one of your side windows a bit to provide a pressure outlet.
budrichard
05-07-2003, 06:34 AM
No solution that I know of. Both my 99XC and 03 XC suffer from the same problem. The real reason is that your XC is on the S80 designed platform and that sunroof opens into a small cabin on the S80. the lenght of The XC allows standing waves to form when the sunroof is open. If you notice when the sun roof opens in auto it DOES NOT go to the full open position. That is to reduce the noise. There was also some drivlle in the 99XC manual about the vehicle being more fuel efficient with windows closed and air on, that with windows open and no air. Who knows if true? -Dick
pico de luuks
05-07-2003, 06:43 AM
I test drove a XC with sunroof. Didn't like the noise and the reduced headroom => no sunroof in my XC.
Wouldn't mind a nice second hand C70 convertible though
http://xc70.com/iB_html/non-cgi/emoticons/cool.gif

http://xc70.com/iB_html/non-cgi/emoticons/pico.gif
wiz
05-07-2003, 06:52 AM
Interesting. I had a 740 with the metal dam and it was much noisier than this XC70. Stupid question here, but I have the cargo net permanently in place. Could that be making a difference to the noise level?
littlewaywelt
05-07-2003, 07:01 AM
It's not the net. It has something to do with the vacuum/difference in air pressure as the air moves over the vehicle and pulls/pushes on the air inside as it moves over the vehicle.  The air dam thing pushes the air just enough over the sunroof so as to reduce the effect. I have noticed a similar effect if I only open 1 rear window. If you open another window or crack one it goes away.
I'm no physicist, but I did stay in a Holiday Inn Express last night.