Date: Mon, 29 Mar 2004 16:43:16 -0500
Reply-To: Karl Ploessl <ploessl@SUNMAC.SPECT.UPENN.EDU>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Karl Ploessl <ploessl@SUNMAC.SPECT.UPENN.EDU>
Subject: Re: Sound Deadener Installation Concerns
Content-Type: text/plain; charset="us-ascii" ; format="flowed"
a follow-up on last weeks disussion.
The following topic came up on the type2 list and it's quite fitting
to the discussion on this list.
Date: Fri, 26 Mar 2004 08:50:22 -0600 (GMT-06:00)
To: type2@type2.com
From: "Chris M." <busbodger@earthlink.net>
Subject: Re: [T2] Link to Soundproofing your VW Bus?
Message-ID: <9598138.1080312623010.JavaMail.root@waldorf.psp.pas.earthlink.net>
Hewett-Bulley page. Dunno the link but use these terms and you'll get some
results.
FWIW a friend pointed me to an ad for that very same old bus they did. He felt
sure it was was the same bus and I did too. Was a rusted mess. I would
SERIOUSLY consider whether I wanted to go this route. Despite their best
efforts it seems some of the noise and insulation projects did indeed trap
something that may have led to serious rust issues. To be fair the bus may
have been up north or near the ocean too. I'm talking hunches here - not
scientific proof - not trying to flame anybody including the Bulley-Hewett
folks.
My advice would be to make a trip to the junkyard and look at various luxury
car interiors and see how the factory sealed out noise. Look under carpets and
inside wall and door panels. Looks to me like they used copious amounts of
jute (which will breathe and dry out) and tar panels (aka Dynamat type stuff).
However even tar panels will trap moisture so the ones I have seen in doors
have many holes cut in them (aka Swiss cheese). The tar panels give mass to
the sheet metal and dampen the vibrations which cause or transmit noise. I did
this to my doors and wow what a difference. Thunk vs. bang.
The plastic wrapper (vapor barriers) I have only found covering cavities that
got some external air circulation (doors). Notice how VW designed it with
vents and louvers to move air about inside the doors. The plastic did not trap
mositure inside the door, just kept it from saturating the door panel
cardboard and probably made it drier inside the vehicle (having driven cars
without door panels in all weather situations the car was damper than with
door panels and plastic installed even if the naked doors did not allow water
to drip inside on the floors).
The VW bus - especially the camper contains alot of hard surfaces (even steel
- how many Lexus or Mercedes have you ridden in with exposed painted steel in
the interior) and alot of flat surfaces at that. I think these really
contribute to the noise. Check motor mounts and tranny mounts (2 of mine had
failed allowing the drivetrain to touch the frame transmitting 984% of the
noise they made!), weather stripping (keep out the wind noise), and then add
jute or closed cell foam (I prefer jute cause it breathes) behind every
upholstery panel and under the carpet. Also sew up a heavy Jute and/or foam
mat to lay over the engine compartment (inside the bus) topped with carpet of
your choice for looks. Be sure it also hangs under the back seat to cover all
the compartment bulkheads. I think that stuff so far will surprise you with
noise reduction. Additional improvements might include replacing rubber floor
mats with carpet over insulation like foam or jute or tar panels or a combo of
each (again check those junkyards for guidance), upholstering anything the
factory covered in vinyl. Hard backing, layer of 1/4" foam, fabric = door
panels. Upholster the vinyl seats. We've done several Hot Rods over the years
and all are surprisingly quiet despite the dual exhaust solid mounted to the
frame (! - Dad's idea of a good idea! <grin!>) and solid engine mounts (? -
been a while - dunno if that is actually how we did it, been over 10 years
since my last Hot Rod build).
Future projects: cover steel interior components with layer of foam and
upholstery. Popular with the Hot Rod crowd. Reckon it would promote silence? I
think it would. I think that is why "modern" cars have plastic panels covering
these portions often with Jute glued on the backside. Appearance and noise
control.
Chris M. in TN
'78 VW Westy Corvair-transplant (still futzing around on the cooling)
A guy had multiple pages showing a interior being stripped out and multi
layer insulation installed to keep out the heat and cold as well as road
noise.
--
Karl
'81 Westy "Jenny"
Wilmington, DE
