Triumph GT6 cage

There must be some Triumph Spitfire / GT6 builds using a full-cage?   I am building a GT6 and would like to see

some examples of how a cage was done.   This car was left for dead to rust, and I would not trust the sills to hold anything together,

so I am planning to build the cage onto the frame, and drop the body onto it.  As you can see, there is no perimeter to the frame.

What are goals for the cage?  Competition use or just structural panel support? 

For the former, I'd recommend attending a few vintage races and looking at how other GT6 race cars have had cages installed. Especially since the cage will need to be inspected and approved by whatever racing group you plan to run with.

For the latter - just get replacement sheet metal and repair the tub, available from any number of sources. Rotten sills and floors is pretty common with these cars.  Or get a new tub.

My GT6 had the entire floorpan done in a single fiberglass mold. It was actulaly much stiffer than stock. But of course would not have been as good to add a cage to. Man, that car was already tiny inside, I couldn't imagine wanted to drive it with a cage! If it's just for street, just do a roll bar. 

The car will be lemons/chump/luckydog racer

Driver size is definitely something to consider. Especially for a lemons/chump car where you often don't really know how big or tall the drivers will be.   I know from experience (I own one) that a GT6 is not a big car even for me at 5' 10" and a fairly average build.  Add a cage and the interior will get tight really fast.  Even more so for Lemons/Chump racing where you will definitely want the cage to be over-built.  Contact in those series is considerably more likely than in say a vintage racing environment. 

I had a 1963 Impala SS and ran round tubes across to round rocker bars.   Essentially a new reinforced frame/floor.  Square tubing would have been much easier to attach the new floor too. 

http://www.348-409.com/forum/threads/x-frame-reinforcing.25457/

In reply to Gasoline :

The problem with that in a GT6 is the floor pan and seat mounting points are below the height of the frame rails - and they have to be or the driver's head will be above the windshield.  

The body tube has two cross beams in the floor spaning between the tunnel and the sill.  One a few inches in front of the seats and another behind the seats (that two of the rear suspension links mount to).  These cross beams are inside the interior space and are significant;y larger than 1x tubing - roughly 2x3.  Example here.