Sound Proofing your Bimmer
The standard soundproofing in the car is pretty good but add something like a sub-woofer or a sports exhaust and things start to rattle and vibrate like crazy. I added Dynamat to the boot of mine purely as my exhaust seemed to reverberate through the boot and it got amplified as it did and I happened to be able to get hold of some off a friend cheaply. See the end section for an independnt review done by Fast Car as there are loads of pruducts available!
The thing to note with dynamat is that you dont need to cover every single inch of space, it is the large flat panels that need damping the most, not tiny little section of metal. For example if you shake a large flat piece of plywood by the edges it makes a Rolf Harris inspired sound, if you do this with a small piece you get less sound purely as it is the large surfaces that flex not the ones.
Preperation is important. You need to make sure all the surfaces are clean, non greasy and dry. The best way to do this is to wipe all surfaces with something like white spirit as this dissovles all the crap that gets in there. Dynamat is most plyable when it is warm, people I know dynamat their cars use a hair dryer but personally I just warm up each section by putting it into a warm oven keeping a careful eye on it, it needs to be warm not hot!. The best tool to use when actually covering is a wallpaper roller as the plastic roller ensures you put even pressure over the entire area and helps you avoid air bubbles.
I discovered that it is the spare wheel well that due to its proximity to the exhaust transmits quite a bit of noise, notably the floor of it as it is made of much thinner metal than the sides, so put a few large section in here and also round the sides but you dont need to use a much here due to the metal being much thicker.
Once the boot floor is done you need to concentrate on the boot lid. For this you need to take out the toolkit and the carpet. The clips that hold the carpet in place are removed by partly levering them out with a blunt knife or wide-bladed screwdriver and then using a much thinner screwdriver once it is partly out and inserting this into the actual split between the retaining arms and pulling it forward as this causes the arms to contract.
The toolkit's plastic hinge is screwed into the boot metal, you need to prise off the plastic covers that are on top of the screws and undo them. The flexible plastic "stop" is removed by simply rotating it 90 degrees and releasing it.
Once the carpet is removed you will see the boot lid due to its construction wont allow for a huge amount of sound proofing. What I did was to cover all four of the oval shaped cut outs, the raised metal section to the right of these and the actualy boot lid top skin, you can only do this in a small section by touch not by sight. I also did all the metal connecting strips where the carpet is secured.
The next area to do is the rear parcel shelf under the grey plastic cover that incorporates the speaker grilles and the actual metal of the back seat. I'll keep you posted when I do these!
2004 BMW 325i Touring SGM
2005 Suzuki GSXR 1000|1992 JDM Civic SiR RHD Black
2000 BMW M5 Avus Blue (GONE)
2002 BMW 325i Touring TVM (GONE)
1994 BMW 325i Saloon Black (GONE)