I have an '88 260E that I've owned for 10 years now and will probably keep for as long as I can maintain it. I would like to improve the sound insulation aspect of the car. What is possible to add to the stock sound "proofing" that already comes on the car? I've replaced the hood pad but would like to better understand what could be done in the doors, etc. Are there any websites that I should look at?

Thanks in advance.

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Rick in Raleigh
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as of May 2011
'97 S320 LWB 325,000 miles
'88 260E 332,000 miles
'72 220D 338,000 miles (sold)
'73 BMW 3.0si 473,000 miles (retired)

If you subscribe to any car audio forums or magazines, you would already know about some of the various sound deadening techniques used by pro audio installers. They go to extremes for audio competitions, and keeping a vehicle quiet is one of the judging categories.

There are pretty much two types of products to achieve this. Insulation sheets or spray foam.

Spray foam seems a bit messy for my tastes, but I suppose it's effective at insulating body cavities where strips of insulation cannot penetrate.

The sound deadener sheets are used throughout the rest of the vehicle, and the best installs have this stuff layered from the headliner down to the carpet. The whole interior is stripped prior to install of course.

The results are outstanding, even for cars already nicely equipped with noise insulation.

Brand names like Acoustiblok come to mind, but I haven't been in the car audio scene for over a decade, so I can't remember the product names...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

I remember back in '92 my friend used a product called dynamat that worked really well, but it was costly.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

Dynamat! That's it! Yeah, this stuff is not cheap!

BTW, post this question over on the audio forum. Lots of knowlegable folks over there, including Scott of LaJolla Audio.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

I was surprised at how much a set of carpet floor mats on top of the regular carpet helped.

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Norm in NJ
Next oil change at 230,000miles

I just did my 300CD with Dynamat Extreme (yes it is expensive) and the results are well worth the effort..The outside noise level has been reduced to well below what I thought it would be...Especially from the trunk where I really laid it on thick for the Sub Box. Worth the effort....

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83 300CDTurbo 307,000
2005 Honda Element 266,000
56 Nash Ambassador Country Club Special 34,000(under restoration presently)

http://www.peachparts.com/shopforum/car-audio-multimedia/125099-123-install-extreme-dynamat.html

Did you do the firewall?

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

I haven't quite gotten that far yet however I plan to give the firewall area an extra measure of the material for obvious reasons. I have had other projects on the car and only so much time but have a vacation coming up soon so that week will be devoted to finishing up the dynamat and installing the stereo. Will post some pictures when I do it....

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83 300CDTurbo 307,000
2005 Honda Element 266,000
56 Nash Ambassador Country Club Special 34,000(under restoration presently)

http://www.peachparts.com/shopforum/showthread.php?t=125099

I seem to recall that the W124 gained weight over the years - several hundres pounds - due partially to increased sound insulation. There might be a way to check body shops for part differences between years - they must replace sound insulation after collissions occasionally.

My 1995 E420 is very quiet at all speeds, of course the extra weight makes the handling a bit different that the earlier W124s.

Troy
1995 E420 92k

I have been reading up on some older large size sedans including the W140 MB, 1997 BMW 7 Series E38, Audi A8, Infinti Q45, 1995 Lexus LS400 and one article on the 1999 Acura RL mentions how Acura engineers have worked overtime figuring out how to make this car quiet and vibration-free. Innovations like low-friction ball joints in the suspension, Teflon seals on the valves, a liquid-filled rear-trailing arm, foam-filled B- and C-pillars, honeycomb floor panels and vibration absorbing seats are just a few of the things the 3.5RL serves up to make you forget that you are in a car. I can see how that can add a few hundred pounds to a car easily.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

Be sure to check that the weatherstrip around the doors is actually sealing. You would be surprised at how much noise comes in from even a tiny crack, torn weatherstrip, or poorly sealing weatherstrip. I have a '98 ML that has a torn weatherstrip on the driver's door and I can't wait to have it replaced!
Use the dollar bill test.

What is the dollar bill test?

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

Put a dollar bill in various places around the door and close the door. If you can pull the dollar bill out then air and noise is getting in. Poor sealing of the door for some reason. In places that the dollar is too small to use then a piece of computer paper can be used - just fold it length-wise to double it so it is the same thickness as a dollar.

Dynamat is a great product, but try another called FatMat. FatMat is a little thinner, but works the same. You can check out www.fatmat.com or find it in huge rolls on ebay. You pay a lot for Dynamat because of the name.

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Ed
-1984 Mercedes 190D 2.2 5-speed gray market(bought@30,000 miles) (Sold back to original owner@170,000 miles)
-1999 Mercedes E300DT (245,000 miles)
-1999 Mercedes S500 Grand Edition (80,000 miles)

Thank You. I will have to give that a try.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz