meilers

I'm looking for any way to quiet down sound from the trunk and rear of the car. Currenty I have a sample of DynaMat that I wrapped the cheapo particle-board cover for the spare compartment with; it made a minimal difference (doesn't rattle when I downshift now!) but I'm not certain where to go next. Has anyone here soundproofed their trunk or a WRX/STI? What did you use? What parts of the trunk are most important?

Obviously I can't sounproof the back of the rear seats (which is where 90% of the sound most likely comes through, unfortunately) -- are there any other strategies? Is soundproofing the inside of the wheel wells helpful?

The inside of the trunk lid is a bunch of exposed members and moving parts, I really don't want to tackle that with the Dynamat -- do any of the spray-on soundproofers work? Oh, and which of the soundproofing materials does NOT smell like a tar roof on a hot day?

nhayden

What type of noise are you trying to reduce?

General road noise - this will take a little work.

I have done two layers of Dynamat on the floor of the trunk plus put a layer over the wheel wells and along the back between the lights and the lid.
On top of that is a layer of thick trunk-liner carpet that is held down with industrial spray-glue. I have a wagon, so I put some extra effort in to get the rear of the car quieter.

You can help reduce noise through the rear seats and rear deck by using MDF or plywood.
Cut a peice of wood to fit the shape of the rear seats and cover it with trunk-line to keep it astetic. Then screw it into the supports of the rear seat. Remember to cut out for the pass through (if you use it). Then you can do the same for the rear deck, this will require some spacer strips in order to clear the levers for the lid. If you have a subwoofer in the trunk you may want to leave the rear deck alone so music can get through.

Putting Dynamat on MDF, particle board or playwood is really a waste. Dynamat is design to reduce vibration in metal and plastic panels. Wood is inheritanly dead and does not really require anything else.

Also consider getting the factory sound deadeding pads from a wagon, with a little trimming I am sure they will fit your sedan.

Another area to consider covering is the inside of the doors. I found there is a lot of road noise that comes in through the doors.

meilers

These are good tips. Does the Dynamat have any lasting smell? Does anyone have a guide for taking the doors apart to put in soundproofing? I looked them over today and I can't see how to take them apart without just having at them with a screwdriver. I think I'll do the rear passenger doors first... This is definitely a Scoobymods topic, I'm surprised no one has done a how-to on this.

Yes, I know the Dynamat was a little wasted on that piece, but I wanted to weigh it down -- currently it is so light it vibrates under many conditions; just wanted to make it HEAVY

I've got the factory sub under the passenger seat, no plans to do a big stereo stystem. However, I am having a louder exhaust installed, and I'd like to minimize the in-cabin effects from doing so (which is why, obviously, I am concentrating on the rear of the car).

nhayden

Taking the doors off is not that hard, takes a little patients the first time.

Remove the cup in the arm rest, single screw under the little cap. This will reveal 1-or-2 screws in it that hold the door panel in place. Remove them.
Remove the trim ring around the lock and handle and the 2 screws long the front part of the panel. There are little caps over the screws.
Remove the triangular piece at the top-front, you may need a large flat screw driver. I would suggest you buy a panel-puller from the local auto parts store. They have rounded edges that will not mar plastic or scratch paint.

Starting the lower rear corner pull the panel away from the door. These are snap-tabs and they should pop out. Do not pull to hard at once because you can crack the panel.
Work your way along the bottom of the panel from back to front, then up each side.
Once you have "popped" the panel off you will have lift it straight up with a little of wiggling to get the trim along the window off.
(this is how I remember it anyway) If you are having a hard time or it feels like something is sticking, check for a hidden screw.

If you are planning ahead for the exhaust, then put additional layers in the area around where the exhaust will be. Also remember the sides of the spare tire well and along the bottom of the tail lights and the panel behind the jack.

If you are not putting and subwoofers in the trunk then feel free to seal over the rear deck. This is probaly overkill but hey, if you have gotten to this point, why stop now.

meilers

Thanks, this is all great stuff. Maybe I'll take pictures when I do it and make a Scoobymods tutorial out of it. I've always been wary of taking the doors apart, afraid I will end up with more rattles than I began with!

I'm going to do every square inch of the inside of the trunk, I just bought some spare clips to put the liners back on after I take them out. My only problem is the SMELL of the dynamat, which seems to be tar and sand stuck on a layer of tinfoil -- nasty stuff, and in 110-degree heat it really stinks. I'm hoping the smell goes away quickly, I did the top of the trunk lid today and I can still smell it on my hands.

syncopation

iTrader: (3)

Somebody beat you to it:

http://www.scoobymods.com/forums/showthread.php?t=137

I did this to the entire car (wagon) about two months after picking up the car. The road noise was just killing me. Replacing the stock tires also toned things down a bit.

The cheap partsexpress dynamat does stink for about two weeks. It's worth it. If I was to do it all again, I would either choose a thicker mat to lay down, or perhaps do two layers on the floor. I did applied two layers to the roof, which made a considerable difference. They also make a headliner acoustic mat, which may be another way to go.

Have fun, and don't forget to wear gloves when pulling out the headliner, or you may get it dirty.

norcalridin

iTrader: (1)

well sometimes its just better to dissasemble the whole car, and then go to a car audio shop that will sound deaden your whole car for like around 300-400 bux.. and they use the spray type deadener which results in less weight and loosing more sound... and its alot easier having someone else who knows what they are doing do it for you.. and its preaty cheap considering that all your doing is stripping down the car.. when doin it yoruself consists of tearing down the car, then going through numourous hours of slapping all the sheets down.. and then heating everything up... and also the cost of all the mats to line the whole car is whole bunch of tEH skrill!!

DLUX WRX

iTrader: (1)

i have just finished installing dynamat on my whole car... doors, trunk, floor etc...
if there was a metal panel that that wasn't "dead" then i got some mat. it does give doors and trunk that thump sound that you hear when you close the door of a VW or a Beamer but it doesn't kill road noise. you would need to install more of that funky fabric mat under the carpet. the mat on our cars is very thin compared to that of a higher end car.
there is an S500 in our shop right now and the mat between the rear seat and the turnk is about 3/4 inch thick to keep the sound out.

bpang1

iTrader: (25)

Dynamat is great but there are other products out there.

www.edesignaudio.com

^^^Their stuff performs better and is cheaper...which is really important due to the cost of Dynamat.

jaydwil

Don, where's your shop?