Rear deck lid rattle

[BMWe30Mstyle]

A lot of my past e30s had this same rattle coming from the rear deck lid when stereo is turned up loader and especially now with my small sub in the trunk. Its getting worse and super annoying!

Anyone have input on where the rear deck lid rattle comes from? I have tried some foam on the speaker mounts but seems to be something under the lid vibrating.

[dwvw]

Put your sub in the interior, or get a lukebox.

[dubdub]

As above notes, where you place your sub will have a great impact (pun intended) on where/if you hear rattles. I used to have my subs facing rear, and even with over 100' of damping material, I still had rattles... now with it facing through my ski hole, the ammount of vibrations is way, way, way down with no damping material.

With that said, there are lots of things in that general area that could resonate with bass notes. The only way to know is to get in there when the bass is bumping and put your hand on different parts. I would guess one of three main areas... the rear metal shelf itself, the carpeted trim on top of the shelf, and the two rods in the trunk that create the tension needed to have the trunk stay up.

Damping material works by adding mass to surfaces, lowering its resonance frequency... find a spot that is vibrating, add heavy tar material until it stops. It is pretty simple, if you don't want to change the placement of your sub(s).

[StereoInstaller1]

Just so you know, my deep hatred of both rattles and Dynamat are both contributing factors in why I design subwoofers the way I do.

The general idea of forcing all of the subwoofers energy into the cabin is nothing new, and in my mind it is the only logical way to deal with it. What we do works by using a foam gasket and carefully contouring the face of the box to fit the trunk wall, so that the metal itself is not subjected to vibrations.

This means you have to have a much higher level of craftsmanship than is required for a traditional subwoofer box, and also is why ours are so much more expensive.

Luke

[einstein57]

I have a rear racing 12" woofer. My solution was to buy a $30 roll of generic tar sound matting. It was enough to cover the rear shelf, transmission tunnel around the shifter, and tracing the path of the catalytic converter on passenger foot well. Then i pucked up a roll of low density weatherstripping foam tape from home depot and placed a few strips under the parcel tray and behind the license plate. No rattles except for the trunk vents. That can be easily fixed but it does not bother me at all. Very minor.

[gearheadE30]

You can also unthread the lid stopper rubber things so there's more tension on the lid, but it might get a little harder to get the trunk to latch.