Six-Point Rollcage in an SPF?

How do you best configure a six-point rollcage in a Superformance model GT40?

It seems best to place the rear most roll bar in the engine compartment, away from the driver's head, in order to increase head room in what is already a cramped cockpit. (Two vertical bars would then punch through the engine bulkhead along the centerline of the car and then bend alongside the outer windshield frame to the floor.) But having done that, there doesn't appear to be a lot of room in the engine compartment, in the SPF anyway, to fit non-curved 5th and 6th brace points onto that roll bar.

I'd be very interested in seeing how others have done it!

Kim

Kim:

Here are some pictures during installation and after of the approach that I took.

1. The main hoop actually penetrates the cross bar where the shoulder harnesses attach. It does not intrude into the engine compartment at all. It is welded to the cross bar as well as just below the roof structure where it penetates the fire wall and ties it all together. I did have to notch the coolant tank for the rear brace.
2. The portion of the cage inside the car is dismountable to allow removal. The tube interface is a ball and socket arrangement that is approved by all sactioning bodies.
3. The main hoop is permanent.
4. You are right there is no way to provide the rear braces without curving them. Only a small portion of the rear braces are visable through the rear window and are below the baffle panel.
5. I made short links that triangulate the rear bars and tie to the base of the main hoop.
6. All material is chromemoly.
7. I electroless nickle plated the small pieces and will powder coat the rest except the main hoop that had to be painted in place.

These cars are so close to the originals that this is the best that I could come up with without changing too much. It's not ideal but I think it will provide some protection. If I want it to look as original as possible I can remove the rear braces and the interior cage and you would likely not even see the main hoop.

I was wondering, if you turned the car over , god forbid, what about the possibility of the front legs punching through the sill and into the fuel tanks?
Any thoughts ?

Intrusion into the fuel tank area is always a possibility but it would be an impact of such intensity that I don't think that I would need to worry about the fire.

The mono structure in that area is where several sub structures come together and form a very strong area. The base of the front hoop is a large plate, just like done in the originals, that is welded to the sponsons and conformal to the rolled ribs. Plus there are two former/longerons below the plate that will effectively move most of the force into the structure. No structural analysis here just a little speculation.

The cage that I did is basisally idental to the ones used in some of the orginal MarkII cars except removable. Although providing much more protection, I elected to not use removable side bars.

Hi Kim,

I don't know if you're interested in making your car legal for SCCA or NASA events, but if you are you might want to check out the 2009 SCCA GCR (General Competition Rules). Therein you'll find cage structures defined for various classes. Probably what you'd wish to do if you wanted to make a SCCA legal cage is check out a GT or Production roll cage. These would also be good for all NASA events and should be overkill for HSR and the like. With my Lola build thread (nope I haven't worked on it since the last post) found here you can have a look at such a cage:

http://www.gt40s.com/forum/gt40-build-logs/18681-build-diary-rcr-lola-t70-spider.html

All the bars in that cage are necessary per the rules. The trouble with GT40s is the down tubes, or the tubes that connect the main hoop with the front hoop. The tubes need to be outboard of your head, else they do you no good. If they are outboard of your head it makes it damn hard to get into the car. Even if the tubes follow the roofline on the GT40 then coupled with the anti intrusion structure you end up with a fairly small shape to get through. The open Lola was far easier since the bars could angle downwards and the car has no roof.

I think it could be done with careful planning and paying attention to the attachment points and cage pad attachments. Also, some of the pieces are required to be one piece with bends only. This requirement made the Lola front hoop a bear to get in place.

Kim-
Do you know if a Superformance owner has converted their GT40 into a SCCA sanctioned and approved track car? What class? If so, that might help anticipate requirements and techniques for getting the roll bar in and compliant. I'm sure there are many other compliance factors as well. This thread may help all SPF owners know which steps to take next.

Mike- nice work on the roll bar and that color on the car is sharp!

Thanks,
Steve