W124 Sound Insulation?
 

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.

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...

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

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.

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

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....

Did you do the firewall?

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....

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.

Make sure the doors are sealing properly
 

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?

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.

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