How much stiffer with solid or tied in roof? Options

[Mueller]

New car has no cage, I know the 914 tends to flex and that the factory welded steel roofs on the 916 for what I guess was to help stiffen them, or was it for other reasons??

The 'glass top should help a little, but I was wondering about attaching tubes or the like from the factory roll bar to the windshield hoop to stiffen the car up....

Has anyone played with this before??

[John]

need more visual proof?

No Eric. That will do. A picture is worth a thousand words as they say.

I tied the windhield frame into the cage at the top of the windshield frame probably 16 years ago.

The windshield frame moved enough on the track that it would actually rub on the cage and would otherwise create noises. During that season, I decided to tie the frame into the cage to prevent the squeaks/rattles. After doing that, I pretty much forgot about it.

The areas that we experience cracked paint is normally in the same area, but further forward. We also (in our infinate wisdom) welded the joint between the fender and cowl. This area would routinely crack the paint until we cut out the joint and replaced it with sheet metal. Our cowl and fender now form a 90 degree sharp corner and this seems to be a stress concentration as that corner is where our paint will crack now.
(I am convinced that this is the reason for the plastic welting in the joint to begin with). In other words, I believe Porsche knew the fenders/cowl/windshield frame moved too much to weld all that together and created the "expansion joint" to address the issue.

I have noticed that the cracks in our paint starting at that sharp corner (stress concentration) start only after a severe jar (dropping a wheel off the edge of the track into a HOLE or hitting VERY VERY bumpy alligator strips). These severe "jars" are HARD. Hard enough to bend a strut (which I have actually done on one occasion).