<VV> Re: VirtualVairs Digest, Vol 13, Issue 15, Msg 6

[WillSmithTFPOCAllenTexas]

Mark,
Here's something for you to consider...the interior air pressure of a 
car in forward motion [blower speed enhanced by ram air entering the 
air conditioning ductwork] is greater than the lower air pressure on 
the outside front and top of the front door glass [verifiable by 
looking at the dirt/moisture pattern on a dirty car]....hence, 
headerless door glass is easier to blow away from its weatherstrip and 
the wind noise that results is primarily the higher pressure air inside 
the car rushing out. I can assure you it was a real 'bitch' of a 
problem with 70s GM cars...especially Cadillacs because those owners 
wanted to go 100 mph+ in total silence and the faster they went the 
worse the problem became. In contrast, a header door is stiffer in that 
area, has more resistance to the pressure difference and therefore 
usually less wind noise. GM had several different weatherstrip cross 
sections trying to design out the problem. GM may have "pawned" the 
explanation off on the public, but I can promise you I've logged many 
hours working windnoise 'heat cases' for Cadillac. Oh yes, we don't 
have very many frozen car doors in Texas so I can't 'feel your pain' on 
that problem. A 'field fix' of that freeze problem would be to put duct 
tape around the door joint to prevent moisture entry, but that would 
work best when the car is not occupied, and it would add to the time it 
takes to open your door if you're trying to get away from 'bad guys' in 
a hurry.

Have a GREAT American Day!
Will Smith, "The Fresh Prince of Corvair"
Former Cadillac & GM Service Training Instructor


Message: 6
Date: Fri, 03 Feb 2006 16:20:45 -0500
From: airvair <airvair at richnet.net>
Subject: Re: <VV> Window headers, was:  Sedan VS Sport Sedan
To: Bryan Blackwell <bryan at skiblack.com>
Cc: Virtual Vairs <virtualvairs at corvair.org>
Message-ID: <43E3C92D.E933D579 at richnet.net>
Content-Type: text/plain; charset=us-ascii

I've always considered that more of an excuse than a plausable reason. I
really don't think that wind noise is necessarily any more of a problem
on a headerless door than a header door. It all has to do with
weatherstrip design. But, yea, that's the "official" reason they pawned
off on the gullible public.

-Mark

Bryan Blackwell wrote:
>
> At least in the case of the Neon, the stated reason to add the headers
> on the 2nd gen cars was to reduce wind noise.  It's more difficult to
> get a good seal without them, and I believe I saw that as a reason in
> references to some of the GM designs as well.
>
> --Bryan
>
> On Feb 3, 2006, at 3:03 AM, airvair wrote:
>
>> I personally wish they would go back to headerless doors, especially
>> since the headers that wrap up into the roof are particularly prone to
>> freezing shut in the winter. I'd also think that doors with headers
>> would be more prone to jambing shut in a rollover situation, thus
>> presenting an increased safety hazard. They certainly don't add
>> anything
>> to the roof strength, despite that illusion.
>>
>> -Mark