Roll bars

One of the things to be sorted is the roll bar. Due to the rear aspect of the car, there is no bracing available like on the original locost. It could be fabricated, but then I'd lose boot space, possibly part of the bodywork, and overall I'm not convinced the strength would be there. I also can't extend forwards into the seating area, because I want to keep it open. 

This leaves me with a piece of metal that is bolted in place with a handful of bolts, and I'm not convinced it would work. The leverage alone on the car would tear the bar off or even destroy the mounting plates, even thinking about it makes me cringe!

However I think I can bring extension bars down between the bodywork and the chassis. This roll bar from MK shows the sort of thing that could be possible;

The highlighted section looks like it would drop down from the rear overhead bar, it could then be mounted directly to the bottom of the chassis. As long as it mounted reasonably high enough it could be both decorative and functional, without losing much/any cabin space. I suspect I'll need to remove the parts of the bodywork that sweep down towards the body, but to be honest they don't fit very well, it's going to take a lot of work to get them in the right place, and I was 80% sure I'd just remove them anyway! 

The next steps for this particular job, in parallel to the seat trimming and the outriggers welding and gluing, will be to fashion an example out of drainpipe. It's an old trick used to route exhausts but it should work to show this as well. The CDS used for roll cages is 44.45mm OD, whereas waste pipe is 40mm OD. As long as I maintain a 2mm gap where required I should be able to replicate a roll bar. So I need a couple lengths of pipe and a roll of gaffer tape!

Just as a quick note, the fixings needed to attach the tubes together are known as saddle clamps. Here is an example; https://www.tomcatwebshop.co.uk/set-of-six-45mm175-roll-cage-saddle-clamps-3012-6-571-p.asp

This is how they're used;

In this example that are at right angles, but I suspect for my roll bar they will need to be at an angle. It is possible to get a hinged joint but I need to make sure they're strong enough and do the job. 

(Update). Here's a quick scribble based on some pointers from the great people over at LCB;