Post by Vindi (Russell) on Mar 11, 2016 22:43:17 GMT
Bit of background first, I bought an aluminium offset style bar a long time ago ... loved the style, but didn't like the idea of something looking like a Roll Bar but being effectively made of cheese. Roll on several years and in a bored moment, I got a proper one made. My idea was to tie it in to the chassis, make it from decent tubing and make sure it was as high up and as far away from my head as possible.
As with anything, it's a compromise. It's as high as it can be, but because I wanted it back behind my head so I couldn't hit it, I was instantly limiting where it could be attached, and how high it could go under the slope of the hood.
I ended up attaching the main hoop to the seat belt tower, for several reasons. Firstly, it's designed to have the seat belts attached to it so is immensely strong and stiff. It allows the main hoop legs to go slightly further apart, and it also makes the legs shorter (and therefore lighter) because of starting higher up. I put a plate in behind the mount so the force is spread, and the mount is L shaped with three bolts per side, one on top (the seat belt bolt) and two on the side.
The main hoop is placed far enough across to allow the seatbelt to work properly. Seems basic, but quite a few bars I'd used forced the seat belt across to the side, preventing it from moving and retracting properly. I also added a bar across the bottom, partly to act as a stiffener, and partly to enable harnesses to be used
As I wanted it to do something more than just look pretty, I added a rear leg. It goes through the parcel shelf and mounts to the chassis next to the rear suspension mount, as far back and as far out to the side as I could get it. This has a reinforcing plate behind it as well, and there are bolts round the outside of the tube that sandwich the chassis floor. There is also a huge bolt that goes up from underneath and attaches into a captive nut welded into the centre of the tube, it goes through a hole that's already present in the car making it easy to locate.
The bars are made by a fabricator who earns his living making chassis and roll bars for a kit car manufacturer ... so this sort of stuff is easy for him! The bars are made from CDS tube, 42mm with a 3mm wall so plenty strong enough. All the mounting and backing plates are CNC cut and so on ... no corners have been cut!!
So this is the first one I made