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It may not be recommended, but theres no reason you cannot drive with a front cage in and no helmet
Respectfully, I completely disagree Freedman. In case of an accident, I'd think the risks presented by a solid metal bar (foamed or not) to be extreme.
Judging Ahab's experience by some of his 'day job' stuff I'm sure he'll make an informed decision that works for him.
Respectfully, I completely disagree Freedman. In case of an accident, I'd think the risks presented by a solid metal bar (foamed or not) to be extreme.
Judging Ahab's experience by some of his 'day job' stuff I'm sure he'll make an informed decision that works for him.
You can of course disagree, but my point was that there is no reason at all you cannot drive a car with a cage without a helmet in the UK
I was hoping my roll cage options spark a discussion as I've rolled many ideas around in my head a lot of times and keep coming up with no one perfect solution.
Originally Posted by HiWind
if you use lw/cf doors, you have to have a front roll cage as the doors are no longer reinforced
but if you have a front roll cage, you cant drive w/o a helmet
and you cant drive on the road with a helmet
so ... if you have lw doors you likely cant drive on the road
I plan to fit lightweight doors which is why in my option 3 to work with a welded rear cage and still undecided front cage/framework I'm thinking of beefing up the sills by bonding in deep sill reinforcing sections made from carbon to help with a side impact. I may even add low height welded in steel cross braced door bars before fitting the carbon structure. Conventional FIA cross braced steel door bars would be easiest but a pain for getting in and out of the car. The Porsche 993 GT1 has door bars but they are compromised to make access easier
Originally Posted by freedman
It may not be recommended, but theres no reason you cannot drive with a front cage in and no helmet
RUF with their integrated roll cage really hug the roof and a-pillar contours very tightly. Porsche with the 993 GT1 road car have a front cage similar to an FIA spec. cage so it doesn't fit as tightly. Both have minimum padding and nothing as extensive as the FIA padding solution Thomas mentioned below.
Originally Posted by ThomasC2
use real FIA-padding on the cage though and not just foam for pipes i.e. It's not enough if your hit a bar with your head, not even with a helmet.
When driving without a helmet the padding thickness brings problems of its own with reduced head clearance. Its designed for hitting with a helmet not a bare head so could do more harm than good. Saying that I think I'd prefer to hit my head on dense foam than a steel tube even with 1" of extra clearance to the steel tube
Originally Posted by HiWind
Respectfully, I completely disagree Freedman. In case of an accident, I'd think the risks presented by a solid metal bar (foamed or not) to be extreme.
Judging Ahab's experience by some of his 'day job' stuff I'm sure he'll make an informed decision that works for him.
The inner roof steel structure is more or less a solid metal bar so for me the same risk as having a cage but only if the distance from the drivers head is the same. Perforated head lining and vinyl don't absorb much energy. If there is less head clearance due to the cage then I'd agree it is a big risk as seat belts stretch a long way during an impact. Which ever way I go I will position my seat to give me as much head clearance as practically possible.
To be honest I'm less worried about track safety than I am road safety as the main reason for building my car is to drive up and over twisty mountain roads mostly in the day but also sometimes on my own at night. The roll cage is just one of many safety mods. I intend to make.
To be continued as I'm far from knowing what the right solution for me is, so please keep the suggestions, observations and ideas coming
you make good points re clearance but the essence is the roll cage is designed for use with helmet.
The FIA foam as in my 996cup is very unpleasant to knock my head into as you say.
I have seen some stiffening in M3's inside the frame ... which is cool ... but not really 964able
I note that Monkey Harris (hi Chris you lurker) did include internal roll cage in his street rod
(among a massive amount of other bracing and seam welding)
Mark34bn's channel has the first vid too which shows this a little too
Bought these a while ago, won't be going on the car just yet but thought I'd post them up anyway
Everything is Alcon, I gave them the full car spec, and they were extremely helpful in guiding me through the various combinations of calipers and discs. I've gone small on everything to reduce unsprung weight, Plan B if I've cut it too fine is to add some caliper mounting spacers and go up on the brake disc diameter.
Front
Rear
Instead of adding extra weight by increasing the thermal mass by going the well worn and successful route of bolting on 993TT calipers and bigger discs etc my approach is a bit more racy.
4 pot calipers front and rear, front discs are 305mm dia. x 28mm thick and rears are 295mm dia. x 25mm thick. They should fit inside a 15" wheel which give me lots of clearance room for cool air ducting.
As I want my car on the light side of lightweight my plan is to manage the brake temps using plenty of ducted cool air. On the front I'll use a combination of the RS ducts and the outer edges of the upper and lower front grill openings. On the rear duct air using a NACA duct in the lower face of the cill cover panel. All air from these openings will be blown through moulded ducting which will be sealed against the caliper and disc to minimise leakage and pressure drop.
This airflow will be ducted to most efficient areas to cool on brakes which are to blow air into the centre of the disc and either side of the caliper body where the brake fluid is around the pistons.
My Dad was selling active cooling fans to race teams and still has some stock. The fans are 8oz and can be set up with all kinds of sensors to run them. They were seeing Brembo rotors go from 1400 degrees down to 760.
11-26-2014, 06:48 AM
