I actually wanted to soundproof this area so I figured out how to remove the rear shelf. I have fold down seats, so bear that in mind.
1. Fold down the rear seats.
2. Pry off the rear speaker covers with a small flathead screwdriver (snaps off easily) and unscrew the midrange speakers with a torx wrench. You can leave the tweeters alone, they are attached to the midrange. (Note, I have the premium sound, so others' speakers may be different.) On the bottom of the midrange speakers, remove the cable attaching the speakers to the rear shelf. Sorry no pics for this, but really straightforward.
3. Remove the three child seat latches on the top of the shelf. To do this, use the hexagonal star attachments with a socket and unscrew. The bolt/latches pull up, along with a bracket that keeps the rear shelf in the right place.
3. Then, you need to locate these fasteners, which hold the black plastic trim piece that holds the front edge of the shelf in place. [Note - my photographic staging of the fastener is wrong in that the inner part of the fastener actually goes into the other end of the outer part. You'll see, it is pretty self explanatory once you are in the back of your car.] The bottoms of the fasteners are under the bottom of the black piece that secures the edge. You just pull back the bottom of the black edge piece and use a flathead screwdriver to push the inner part of the fastener out of the outer shell part of the fastener. I think there are five of these fasteners. Maybe four.
3. These are the only things holding the rear shelf in place, besides lots of friction on the sides (between the upper interior panels where the word "airbag" is embossed) and the back (with the plastic piece that hits the rear window). Now you essentially pull and wiggle the rear shelf out. I found it helpful to lift the center of the shelf to make the shape of an A frame tent. Don't worry about making a crease in the shelf. The material bends nicely.
That covers the removal of the rear shelf. To reinstall, just reverse the steps. Be careful when screwing in the child seat fasteners that you screw them in straight. They easily screw in off kilter and one of mine got stuck which was not fun.
While everything is apart, you can soundproof.
4. I wrapped the metal front lip with felt tape, and put foam tape on the front metal and tops of the four square boxes (one beige box with electronics and three, I think, for seatbelts). These are all opportunities for the shelf to bang into something hard.
I guess I am out of photos, so look at the pic above to see the foam tape on the beige box and you should know what I mean about the tops of the boxes.
A couple other soundproofing ideas:
- Under the foam there are some speaker wires that move around and can hit metal. I taped them down with electrical tape.
- There is a pretty big cavern of space in the back. I placed some strategically cut pieces of foam (from a mattress topper) into this space. This also stabilizes the rear shelf and when I bang on it now, it is like hitting a pillow. Not a sound. Just be careful not to put so much foam as to create a rise in the rear shelf.
- I also placed a 1" square piece of foam inside the three child latches to prevent the U shaped top from clicking when resting inside the latch. Essentially, just put some foam on top of the torx bolt that you screwed back in.
That is it. Quiet as can be now back there.