hey all, in the process of adding a stereo to my STi, (diamond audio all around, two 10" JL audio subs in the back), i got what i would quantify as an ungodly amount of rattle from the rear deck, you know, that part that connects the top of the rear seat and the bottom of the rear windshield.....

anyway, i dynamatted it.......no dice, it didnt fix the problem.....in fact i was driving around and got so *annoyed* that i grabbed the nearest thing to me (a red jacket) and whipped it back there....well it landed perfectly on the deck....AND cured the rattle, 100% anyone have similar problems? and have more permanent solutions? im kinda sick of driving around with a jacket in my rear window.

On my install, I had what I believed to be rear deck rattle as well. It turned out to be the rear deck speakers smacking the speaker frames instead. The subs were building up so much pressure in the trunk that they were sucking and blowing the rear deck speakers from one extreme of the speaker surround to the next. I went to the local stereo shop and bought a set of speaker baffles to go behind the rear deck speakers and problem solved. Now the next part of my problem is after 4 months of use...the rear wing is fractured at the mounting points , and there's nothing I can do or dynamat to fix the 3rd brakelight rattle which is the only thing you hear on the outside. The rear spolier probably wouldn't be broken if it had a center support to reduce the flexing ( near 2 inches ).

yeah, i had that problem in my last car...the same subs i still have were basically compressing the rear deck speakers everytime an impressive bass note hit.....but i wish that were the problem in the roo, but there are no deck speakers, the rear ones are actually in the rear doors.....but there is a lot of....stuff....inside the trunk on the underside of the deck, so that may be the culprit. but like i said, the magic jacket has me temporarilly solved:banana:

Ok, I wasn't aware of the '04 speakers being in the doors. It has to be a deck issue then. You may not be able to get rid of it by simply using a few squares of dynamat.I have had installs to run so much power that a layer of terry cloth had to be used to fill the gap and eliminate the rattle. It's better to fill the gap than to try and glue it down and have to rip it apart later.I've even considered expandable foam on my next spoiler to try and dampen it some.

Isn't it the 3rd tail light on the inside on the rear deck that is the source of the rattle?
If so, how can i take it apart and deaden the noise? I notice this rattle only from certain frequencies from my sub.

The WRX and STi have the 3rd brake light in the spoiler and not in the rear deck.
If you don't have a spoiler that could be it then.

I do have a spoiler.
what does that do to noice?

You may have to disassemble the rear deck and attached components and take some dynamat to the parts where they attach or use something like cork board to make a gasket type component to go with the parts removed to deaden the noise.With the 3rd brake light in the rear deck it should come out pretty easy after you remove the rear deck. the housing itself should be no more than a couple of screws since you need access to it to change out the bulbs. You may be able to refer to the manual to get instructions on the brake light removal .

what do you call the red thing on the rear deck?

It could be the third brake light, but most likely, it will be the deck itself vibrating because it's just floating in the air. What I did was stuffing the gap between the deck itself and the metal body right underneath the deck at three points. (driver/passenger side, and one in the middle)

No more rattle from the rear.

The reason why there was no rattle when you threw your jacket is probably it added more weight on the deck.

Try turning on the bass and press the deck with your hand. You will see what I mean.

I'll try it!