necessity of a roof

[haygood at myway.com (Brian Haygood)]

I'm going to respectfully disagree with Al here.  If each side of the car were perfectly rigid, you would still get some twisting of the body because the sides would rotate relative to each other.  The thing that prevents this is the floor pan and the roof.  On the roof side, if you had no roof panel whatsoever, then you would be concentrating your resistance to twisting at the corners where the side rails meet the front and rear roof fails.  With no roof panel to help out, the stress at these spot welded intersections would be significantly higher.  How high would it be?  I don't know, but I wouldn't want to find out on my own car.



Don't underestimate the structural rigidity provided by a thin sheet.  Consider that stressed skin construction is common in aircraft, often using sheets of aluminum that are considerably more thin than our roof panels.  They use spars underneath that would fail without the skin to keep the spars from twisting apart at their joints.



So what I'm basically saying is that 



1)the stress would be significantly increased if you just take out the roof, or a majority thereof, and do nothing else.



2) Our cars have all the torsional rigidity of a rubber band to begin with



3) By the time you have the headliner out and are up there cutting stuff away, it doesn't take much to put in some small braces between the front and side rails and the rear and side rails.  In fact, I would use the sheetmetal cut from the roof to make some boxes I could either weld or epoxy in at the corners.  I can explain that better if you are interested, but it would be dirt simple to do.  



Brian





 --- On Mon 07/03, Allyn < amalventano1@tds.net > wrote:

From: Allyn [mailto: amalventano1@tds.net]

To: foxxinabox@wideopenwest.com, scirocco-l@scirocco.org

Date: Mon, 3 Jul 2006 07:38:14 -0400

Subject: RE: necessity of a roof



So long as the side rails remain, removal of the center sheet of steel should have a negligible effect.  It is the tying of the A,<br>B, and C pillars that give the extra rigidity, and the side rails have significantly more rigidity than the thin roof body panel<br>itself.<br>HTH<br>Al<br><br><br>>    i know that there are convertible sciroccos and cabriolets <br>> with extra body support rolling around out there with for the <br>> lack of a steel roof. <br>> but, what i'm wondering, would extra support be necessary if <br>> the frame of the roof is there and not the middle section? in <br>> essence, to convert the roof into one big sunroof? <br>> harebrained, i know. i just see these ads for new cars with a <br>> vertical sunroof rather than a horizontal one and wondering <br>> if the middle man couldn't just be skipped. now, on with normal life.<br><br><br>_______________________________________________<br>Scirocco-l mailing 
list<br>Scirocco-l@scirocco.org<br>http://neubayern.net/mailman/listinfo/scirocco-l<br>

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