Date:         Tue, 19 Oct 2004 01:44:48 -0400
Reply-To:     Kim Brennan <kimbrennan@MAC.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Kim Brennan <kimbrennan@MAC.COM>
Subject:      Re: noise reduction
In-Reply-To:  <20041019051611.91383.qmail@web13601.mail.yahoo.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed

Modern cars, and especially luxury cars have a very quiet ride. They
also have a lot of noise deadening materials between the outside and
the inside...

Vanagons, by their very design don't have as much space in the doors
(for instance) as my Jaguar Vanden Plas. That limits how much deadening
material you can put in the door. Dynamat, B-Quiet, and BrownBread are
very thin materials,l whose primary purpose is to reduce the resonance
of the surface they are placed on...usually the sheet metal of the
vehicle. Other materials are needed to reduce the noise that pentrates
that is not due to resonance. Tire noise is one thing. Different tires
have different amounts of noise. Tire manufacturers spend a lot of time
redesigning their treads for the purpose of canceling out the noise the
tread generates on pavement. Mostly, they do a remarkable job.

However, the noise from the tires isn't coming (primarly) through your
doors. it's coming from underneath the vehicle, so if you aren't
dealing with blanking the noise from down below, you won't be silencing
your vehicle. That means the tire wells...and the area underneath the
front seats. In the back its the area right behind the rear seat.

The other two major sources of noise are wind noise and engine noise.
At highway speeds, the wind is hitting the front of your van. That
means you have to have noise deadening material up front, like in front
of your dash. One of those projects that will require pulling the
dash...

Engine noise comes from the back. In my passenger van  there is some
soft of asphalt like material on the top side of the engine compartment
(which has been painted over). Probably something similar to one of the
above products. However, without some additional sound proofing
material, there isn't much else insulating the engine noise from the
main compartment.

Of course, I have an advantage in that I have Syncros. Syncros have the
gas tank in the back, and that provides quite a bit of buffer above the
transmission, leaving the only the area on top of the engine has
needing sound proofing.