Since this is going to be a fairly important part of the car, it gets a page of it's own. When I first started planning this car, the intent was for an all-in-wonder. Meaning it was going to do street, autocross, and track. A full cage was not very practical for a car of this type, so a 6-point roll bar was originally built for it. As time went on, it was determined that this was going to be mainly a track and occasional autocross car. Forget about making it street legal.
I had the opportunity to ride in a completed version of this very car at Summit Point Motorsports Park. It was fast, fun, and scary at the same time. The car was equipped with a 4-point roll bar only. I couldn't help but feel pretty "naked" while traveling at 125mph next to a 2000-3000lb car at the same time. It was VERY clear that nothing short of a full roll cage would be adequate for a track car.
Here are a few pictures of the original 6-point roll bar that was started for the car. Luckily, everything is just tacked in place for now, so a redesign is not a total loss.
2/22/06 - While waiting for some other parts to come in, I started working on the new roll cage. For now I am just starting the back half. The entire unit will be "bolt-on" for a variety of reasons. 1) It will be easier to finish and panel the car with the roll cage off. 2) There will be times when it will be handy to have it removed for maintenance on the car. 3) If the car ever gets wrecked, and the cage is still good and the frame is tweaked, it could be used on another frame.
Here is what has been done so far. First the upper 3/4" round hoop that defines the upper part of the rear body was removed and remade. The original one was bent in two places from shipping. I also wanted to move the front mounting locations on top of the shock towers. Another piece of 3/4" tube will be bent on the radius that matches up with the curve of the fender and continue across the top of the shock tower down to the frame rail. This is purely aesthetic.
Next some vertical supports were added in the same diameter as the roll bar tubing from the lower part of the frame to the newly made hoop. This is to both add support for the legs of the roll cage in the rear and to provide a structure to help protect the fuel cell in a rear impact.
A strong base was added to the main hoop of the cage. I feel like the original frame design is a little weak in the shock mount area, and do not like the idea of attaching the roll cage directly to the shock towers. The base is made from two pieces of 1"x2"x.083" rectangle tubes. These are welded in the middle, then welded fully to the shock towers along with the frame rail that goes between them. Eight threaded inserts were made and welded into this assembly for the main hoop of the roll cage to be bolted to.
So far, only the main hoop is finished and the rear supports have been added. Additional bracing will be added once I get more tubing and once the fuel cell is fit into place. I will be able to start making the front mounting points in the mean time.
3/24/06 - The roll cage fabrication is finished. I have built a few cages over the past 2-3 years, and I will have to say this was one of the most challenging. It was about the easiest to build due to it being all on the outside of the car, but it was the most challenging to design. Since my car will be a dedicated track car, it was decided that a full cage was going to be needed rather than just a roll bar. I would have liked to have designed a "low front hoop" cage to save a little weight and to keep the weight lower overall. Since I will be sharing the track with plenty of other cars that are taller and much heavier, I decided to go with a traditional type cage. I really don't want another car (or anything else for that matter) to end up in my lap. I wrestled with the design in my head for quite a while and am pretty happy with the outcome. Maybe not perfect, but as close as I can get it.
The front four mounting points are supported by bosses that are bolted to 3/16" plates welded to the frame rails. This allows the removal of the cage and a solid mounting point for each leg.
The "door" bars and "roof" bars are designed to give the occupants as much room from them as possible while not having "large" bends that would compromise the strength. There is only one door bar for now. It is in a position to do the most good. IF the car ever goes wheel to wheel racing, it will need an additional door bar on each side. Placing the additional bar far enough from the existing door bar do do any good will then make entry and exit from the car from the roof opening only.
More Pictures of the finished cage:
2/28/07 - Roll Cage Painted...and a Special Project
The roll cage is now all nice and black and has a finished look now. I can't wait to get it back on the car. A few other odds and ends need to get done first. There is also a shot of the car from the rear without the cage. Sometimes I think it would look way cooler with just a 4-point roll bar. The cage is better for the track though...
A couple weeks ago my good friend Stefan came down and we (in 2 1/2 days) made a nice bolt-in 7-point roll bar for his Vintage Saab Sonnet V4 Spyder (Saab never made a Spyder BTW) It only had a 3-point roll bar before we started that was narrow and went below the driver's head. We were pretty happy with it when it was finished and he plans on having it powdercoated before taking the car out this spring.