Caging T-70 Coupe?

Kent · 23rd April 2012, 10:36 PM

In working on my (tube chassis) mk3, I'm playing with ideas on how best to run the cage. I've been searching for photos of mk3s with a cage, and am not really finding much detail on how this is best done. The bodywork is limiting. It's easy to see how to run a front and rear hoop, but it's messy connecting the two hoops, since there's limited headroom already, plus the thinness of the roof between the doors.

Also wondering about favorite ways to connect the diagonals (thru the body) to the rear hoop. Just do a double shear rod end/ clevis? I found this: Lola Heritage News ...but can't really tell what they've done there?

Also, as for building the cage to be compliant for one sanctioning body or another, I'm not that well versed in these regulations. I was just going to use DOM, not Chromoly- I'm only going to do some track days with it, so it won't matter to me, though if I sold it along in 10 years, the new owner may want to go racing, so I'm at least thinking about this.. Any input here is welcome. But my main reason for the cage (Which would just be integrated into the chassis) is for rigidity, not for a certain sanctioning body.

Thanks in advance for any help!

Mark Maybury · 24th April 2012, 12:17 AM

Kent,
On my RCR70 they ran 2 tubes close together in the center at the roof.
And at the back it is the same as the GT40.
I am sure Johan has some good pictures and will chime in.
On another note be sure to use tubing of a large enough Dia and wall thickness to meet any requirement.
In my case I need to pull out the factory cage and remake it in 1-5/8" or greater tubing as the ECTA requires that Dia or greater.
Regards,
Mark

Jeff Young · 24th April 2012, 01:41 PM

If you want it to meet NASA or SCCA specs, get a rule book now! Seriously, you can screw this up too easily because the rules can be difficult to understand in some places.

From what little I've seen of the coupes, I think a "modern" SCCA/FIA/NASA cage is going to be tough to pull off.

Kent · 26th April 2012, 11:19 PM

Thanks Mark! Gotcha on the two tubes. That's the route I'll go, I just wanted to make sure that with a helmet on, they don't end up in the way. I'll do some test fitting, it's easy enough to slouch more/ change the seating angle if clearance is an issue. Your factory cage is 1 1/2" I'm guessing? Again, great info, as I was on the fence between 1 1/2" and 1 3/4", guess that sells me on the latter.

And good info Jeff, I've picked up the scca rule book. Definitely, after taking a look, a modern cage seems really tough to pull off, especially if you want to keep the car a 2-seater.

Johan · 26th May 2012, 09:24 AM

A series of non padded bars close to your head (within a foot or two) is not a great idea
In a car where the occupant does not wear a helmet. That said, the way a Porsche 962 does it is to mold the hoops into the cab, or mold the cab around the hoops. Door bars are low and really only serve to protect the side pod fuel cells, more so than the driver as they are at about elbow level.
The diagonal from the rear hoop to the front footwell pretty much takes up the passenger area.
This can be made to be removable but care must be taken not to have a bunch of hard sharp protrusions in the cockpit. It sort of ends up being a car you do not wish to crash. More of a structure can be fit to a spyder than a coupe. I have pictures but they are too large to post from my phone as I have no way to resize them. The bottom line is that you could build something that would be better than nothing, but building a cage that would be the equivalent of a modern safety system would be about impossible keeping the outward dimensions of the car intact. Just look at the dimensions on the cockpit of a Daytona Prototype.

Darren · 26th May 2012, 02:46 PM

Just for starters, here is a continuation car roll cage "naked" so to speak. I'll have to trawl through my folders to see if I have any close-ups of the various points. The main hoop locates into cups on the radius rod towers and is clamped in by the seat belt bar and radius rod through bolt.The forward part of the cage is just to give stability to the centre section molding and for the door hinges to pick up on.The main cage is bonded into the centre section, then the 2 rear drag links fitted after final assembly. Hope these help.

Darren

Darren · 26th May 2012, 03:03 PM

Just found this one too. Shows the mounting cup on the radius rod tower and fastening with seat belt bar. Also the plate half way along the diag that gives support to the door latch. On the front bar you can see fitting for door hinge.

Darren

Kent · 7th September 2012, 02:19 AM

Johan & Darren,

Thanks so much again for helping me out. Those pix are a huge help Darren, I couldn't have visualized that quite that way.

... fyi, haven't been on the forum, haven't touched my lola at all. I'll be back to working on it in October when I'm done with other life/work/travel distractions.