Date: Wed, 22 Apr 2009 10:54:25 -0700
Reply-To: Neil2 <vidublu@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil2 <vidublu@GMAIL.COM>
Subject: Re: Westfakia, Poptop, Access, Design
In-Reply-To: <49EE599D.3060702@cox.net>
Content-Type: text/plain; charset=ISO-8859-1
Someone in CA who works at a well known Vanagon supplier/refurbishment
company, told me if one doesn't take the Vanagon offroad the standard sized
Westy opening cut in a Vanagon poses little problems.
Again, similar to what Mr. Drillock stated, I had perhaps hoped to only cut
a hole half the size of the sunroof/westy hole but now that I hear all the
integrity arguments I definitely would do so only ACROSS the roof not
lengthwise and likely only between the first and second roof extrusions. I
only need enough room for to stand and unlatch the pt and allow
access/egress from the pt.
I also toyed with the idea of constructing a thin, aluminum ladder to store
in the pt and made to fit from the ground to the luggage rack. This would
allow the Vanagon roof to go unscathed and the children would like it even
better. More like a real tree house! I'd have to cover the luggage rack
with some form fitting plywood contraption while in port, so as to not
stress the roof below it.
I plan to buy a roof tent now but will follow this thread to the bitter end,
since I started this argument and want to ensure my bad name isn't cleaned
up!
On Tue, Apr 21, 2009 at 4:41 PM, mark drillock <mdrillock@cox.net> wrote:
> I agree, but no one suggested removing the entire roof skin. Only a
> section for standing in the main floor area is trimmed out, and not
> anywhere near all the way to the gutters. Cut 1/3 of the center of the
> shoebox lid out and not all the way to the edge and see the minimal
> impact on rigidity.
>
> Mark
>
>
>
> Mike wrote:
>
>> In a 'unibody' (also referred to as 'monocoque') design structure, any
>> skin section is a structurally-stressed component of the entire
>> structure. A Vanagon is considered unibody, even though it does
>> have frame strengthening members underneath.
>> Those roof support arches are more for rollover protection than
>> torsional rigidity of the body. The roof skin, however, is an
>> engineered, diagonal bracing that contributes greatly to torsional
>> rigidity of the entire body, in addition to providing added metal
>> structure to add crash or rollover protection.
>> Take a shoe box, remove the lid and grab the ends and attempt to twist
>> it; it will easily deform.
>> Now, put the lid on and repeat; you'll have a hard time deforming the
>> box from it's basic shape.
>> And, now, for the final proof of the body weakness created by a
>> large, unreinforced sunroof opening; cut a good -sized 'sunroof' into
>> your shoebox lid and repeat your twist test. What happens? My bet is
>> that a great amount of overall rigidity is lost due the 'missing' area.
>> You've cut the center out of your 'diagonal bracing!
>> VW made up for it by adding 'doublers' inside the factory sunroof, not
>> just a couple of cross ribs. The probably also added outboard, lower
>> frame cover plates (I know they did on the earlier buses). Side impact
>> crash protection, must also be taken into consideration in this
>> modification. (Smack the side of the shoebox to demonstrate this aspect.)
>>
>> Mike B.
>>
>>
>>
>>
>> As long as you don't cut the 2 main roof arches, one at the front edge
>> of the slider door and one at the rear edge, the roof area between is
>> just roof skin and not of much importance structurally, IMHO.
>>
>
--
Neil2
'82 Diesel Westfalia (USS Tinosa)
'86 Vanagon/Westfalia Wannabe (SaVannah)
Nunquam Pendite Divendium
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