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in my 1998 900SET, I added quite a bit of Dynamat type sound damping material to both the indside and outsdie skins of the door. This eliminated most of the rattles in my case.
SOUND DAMPING IN A 1998 SAAB 900SET 5-DOOR.
By Rob Mustard (aka REM in Seattle)
Search word: rem_mod
Last updated January 25, 2002
SOUND DAMPING
I mainly listen to jazz and blues and found the amount of road noise a bit too intrusive. So I decided to add sound damping and absorbing material where possible. The following details the current sound deadening material found in my 1998 SAAB 900SET 5-door and what modifications I made.
Front Wheel Wells and Floor Boards:
Under the carpet is a .070 thick asphalt mat covered by an approx. .090 thick white closed cell foam mat with a strong synthetic rubber backing. These two materials cover the entire area from the behind the dash, down the firewall to the beginning of the front seats, and from front left wheel well to right front wheel well including the center console.
There was no need, or much room, to add anything in this area.
Front Doors:
The interior door panel is made of a good quality pressed composite board. There are two pieces of rigid foam glued to the back of the interior door panel. Under the interior door panel is a foamed synthetic rubber membrane covering the entire inside door skin. The membrane is adhered to the door skin along the bottom edge and along both sides. The top is not adhered. Under this membrane is a smaller rubber membrane with an adhesive backing that covers the electric window motor assembly. The exterior door skin (the sheet metal skin that makes up the exterior surface of the car) has a piece of .070 thick asphalt sheet approx. 4 by 18 applied to the lower portion of the door skin. There are three pieces of rigid foam wedged in to the door. Two pieces are wedged at the bottom of the door between the inner and outer door skins, and one piece is wedged as a stopper in the square opening of the inner door skin.
I added a piece of .060 thick Dynamat Super approx. 5 wide by the width of the door to the inside of the exterior door skin, just above the side collision reinforcing bar. I also added an 8 by 8 piece of Dynamat Super to the inside of the exterior door skin directly behind the door mounted mid-bass speaker. After replacing the factory rigid foam pieces, I then covered the lower half (approx. 12 high) of the interior door skin with Dynamat Premium. I then replaced the two factory rubber membranes and the interior door panel.
Rear Doors:
Like the front doors, the interior door panel is made of a good quality pressed composite board. There are two pieces of rigid foam glued to the back of the interior door panel. Under the interior door panel is a foamed synthetic rubber membrane covering the entire inside door skin. The membrane is adhered to the door skin along the bottom edge and along both sides. The top is not adhered. Under this membrane is a smaller rubber membrane with an adhesive backing that covers the electric window motor assembly. The exterior door skin (the sheet metal skin that makes up the exterior surface of the car) has a piece of .070 thick asphalt sheet approx. 4 by 18 applied to the lower portion of the door skin. There is a piece of rigid foam glued to the inside surface of the exterior door skin. There is also one piece of rigid foam wedged at the bottom of the door between the inner and outer door skins.
I added a piece of .060 thick Dynamat Super approx. 5 wide by 14 long to the inside of the exterior door skin, just above the side collision reinforcing bar. After replacing the factory rigid foam piece, I then covered the lower half (approx. 12 high) of the interior door skin with Dynamat Premium. I then replaced the two factory rubber membranes and the interior door panel.
Rear Cargo Area:
I exposed the rear cargo area by removing the carpet covering the wheel wells on each side, cargo area carpet mat, spare tire, tools, etc. The rear wheel wells each have three small pieces of .070 asphalt mat applied to them. One at the front of the wheel well, one at the middle, and one at the rear of the wheel well. The inside surface of the exterior skin of each rear quarter panel has one piece of .070 asphalt mat approx. 4 by 18 attached to it. There is also an 8 by 24 piece of soft foam wrapped in plastic inserted between the inner and outer skins of the quarter panels on each side. There is a .070 asphalt mat covering the cargo floor above the rear muffler. The hatch lid has no sound damping material at all.
I covered the rear wheels wells with Dynamat Super. I also covered the exposed cargo floor on each side of the spare wheel well with Dynamat Super. I then covered the spare tire well with Dynamat Premium. I used some left over scraps of Dynamat Premium to cover the rear speaker shelves and to apply to the hatch lid. I also applied about 6 square feet of .75 thick Soundcoat sound absorbing foam (similar to Dynaliner by Dynamat) behind the carpet in the area around the rear speakers.
Conclusion:
The additional sound deadening seems to have reduced the road noise by about 10-25%. The doors close with a more vault like thunk. The mid-bass speakers seem to be a bit clearer, and there is less sympathetic vibration apparent in the door at loud volumes. There is definitely a lot less road noise from the rear cargo area of the car. I would guess that the Dynamat claim of a 3 dB reduction in the road noise level is about right. The sound damping in the rear wheel wells and cargo area is probably the most important aspect of this improvement. I would rate this experiment as $250 and 2 days well spent.
Additional Notes:
I used one 12 square foot sheet of Dynamat Super (a .060 thick rubberized material with a 5 mil aluminum foil covering on one side and pressure sensitive adhesive on the other side) and two 13 square foot sheets of Dynamat Premium (a .045 thick mineral filled rubberized material with pressure sensitive adhesive on one side). I purchased the material from Crutchfield (http://www.crutchfield.com). The total weight of the material added less than 15 lbs to the car. For product specifications see (http://www.dynamat.com). There are several comparable sound damping materials available at car stereo retailers (Cascade, Accumat, B-Quiet, etc.). An inexpensive source of sound deadening material can be found at McMaster (http://www.mcmaster-carr.com) searching under sound control.
The SAAB Service Manual, Section 8.2 Interior Equipment, was very informative when it came to removing the interior door panels, rocker covers, etc. The SAAB Service Manual is available at your SAAB dealer for about $12.
While I had the door panels off, I added some Wurth Body Protection Spray (a clear rust proofing wax compound for door panels, doorsills, etc. Very thin when applied, it gets into all the crevices and dries to form a hard, protective wax coating). One spray can had more than enough material to all 4 doors and the hatch lid. Available from Car Care Specialties (http://www.carcareonline.com).
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