I am restoring my 69 ragtop and am amazed at the amount of flex in it. I really don't want to install frame connectors, because I don't like the look of them.I was thinking about welding a 1/4" steel plate to each side of the tunnel inside the car. I was wondering if anybody else had tried anything like this or could steer me in a better dicection.

First of all, make sure that your car has all the extra goodies that convertibles came with:
X Brace
cocktail shakers
special convertible-only rockers
cross braced floor pans
(seems like I'm forgetting something...someone else will fill in the blanks, I'm sure)
And make sure the suspension is solid!
Check your frame-to-body bushings.

Remember, the convertible will flex (and twist) in all directions (depending on the road, speed and torque, braking, etc.)...thanks in part to the semi-unitized construction and subframe. So you need everything working together. But the weakest link, even in a well-sorted out car, is the space between the front subframe rails and the rear frame rails. Thats where the extra-strength rockers are supposed to take over, for front to rear stability. The x bracing and floorpans are supposed to help handle the left-right shakes and the cocktail shakers help handle the other vibrations and oscillations inherent in the design. The actual body does the rest, so you can see how rust would affect that part.
All of this, with good suspsension...especially shocks, sway bars and springs...have to be up to the task. And thats on a new car! But these cars are 35 years old now, and they need a little help. Thats where the subframe connectors come in. Simply stated, they work. For coupes as well as convertibles. I know some coupe guys who put them in, although those guys are running monster motors! And there are different types of sfc's. Sounds like you have an idea that may have merit, in conjunction with all the other components. It would be interesting to see how you would do it.
There are lots of posts and opinions here regarding everything I mentioned, and more. Do a search on the subjects...more info than you can read in day!
And maybe somebody here has tried something similar to what you are proposing. Personally, I'll stick with my sfc's, and the setup I have now. I'm just about dialed in!

Originally posted by bills 69:
I am restoring my 69 ragtop and am amazed at the amount of flex in it. I really don't want to install frame connectors, because I don't like the look of them.I was thinking about welding a 1/4" steel plate to each side of the tunnel inside the car. I was wondering if anybody else had tried anything like this or could steer me in a better dicection. Subframe connectors made all the difference in the world to my converitble. Best upgrade by far that I have done.

DS&E SFC webpage (http://www.detroitspeed.com/SubframeConnectors10.html)

Pics of my DS&E SFC installation (http://homepage.mac.com/bspears/PhotoAlbum6.html)

Make sure you get the DS&E solid body bushings as well. They, along with the SFC's, will really improve the ride.

Good luck with your project.

bob graemlins/beers.gif

steve, you forgot the supports that go inside the rear panels.

You guys make a strong case for the sfc's, and the fit with the floor cut out looks great. But right now I have the car completely disasembled and at what point should the sfc's be installed so that the car is not twisted?

Angelglo,
I guess I forgot because I'm not sure what you are talking about. Tell me more...

Bills69,
I didn't install mine (GW) until I was sure that the subframe alignment was as perfect as could be. That would mean the car has to be together, and all measurements done at least twice. Maybe one of the other guys has a different way of doing it and will chime in here...but subframe alignment is crucial prior to installing any type of sfc.