FIA Rollbar effectiveness.

[Pete]

This is not terribly PC as it goes against club policy, but I have some doubts over the worth of the so-called FIA roll bar. The configuration of the bar is angled forward and given the fact that the rear braces are fixed to a tube at the back of the boot that is about as thick as my finger, I suspect that there is a good chance that the roll bar will collapse forward in a crash, unless the Petty Strut is fitted.

 

As most of us drive around without the Petty Strut, for obvious reasons, is the FIA roll bar really effective?

 

Incidentally, I understand that the FIA certification was obtained with the Petty Strut fitted..............

 

Pete (donning tin helmet and heading for a deep shelter).

 

 

[Anthony]

Apologies for the dense response, but is it not a requirement to use the petty strut in competition ?

[mav]

Pete,

 

Don't hide. The more the safety stuff gets covered the better for all of us. I have mentioned this to a few people also. If carrying a pax on trackdays, it would become a little difficult, however I think they should always be fitted for cometition such as sprints etc

 

 

[Drumster]

I always thought that if you imagined the car upside down then the FIA bar would be perpendicular to the ground and hence less likely to collapse

 

Chris Alston

 

1800 Supersprint - Loud and Proud 😬 ...well it only sounds fast officer 😳

Brooklands aeroscreens for those........flies in the teeth moments

Drive it like you stole it!

[Alex Birtwisle]

IIRC there are a few people on Blatchat who have rolled their 7's. The stories that I have heard have all been quite favourable with FIA bars staying pretty much in the right place and only getting scuffed where contact with the ground was made. I changed my bar in favour of the FIA bar after an incident last summer.

 

With regard to the Petty Strut:

however I think they should always be fitted for cometition such as sprints

I couldn't agree more.

 

Alex B

 

 

 

 

S713UMY

1.8K Viper Blue and Black

 

[Red SLR]

I think there have been 2 on here who have rolled their 7s with FIA bars - both were 100% ok - the bar did not even bend.

 

Dont forget the car only weighs 500kg so you will have to be giving it some to get that bar to bend.

 

OTOH I have seen a 7 in a ditch with std bar - the driver did not make it.

 

I would only have an FIA bar on my car - esp on track days.

 

See X777CAT here

 

[Swiss_Tony]

The FIA rollbar is only FIA approved when it has the petty strut fitted.

I came across this when I got my RAC logbook.

If you look at a 7 with and without the Petty strut it will be obvious why.

This is why its required for race use etc.

I think the point about track days is that its a huge improvement over a standard bar not only in height terms but in overall strength ie the tube diameter and bracing etc. Also the FIA bar is made from CDS - the standard one is not.

 

 

James

Su77on Se7ens

 

[Peter Carmichael]

The petty strut imporves chassis stiffness and handling to a non-trivial extent. Daft not to fit it for competition regardless of safety requirements.

[Steve-B]

i thought long and hard about the factory bar, or the FIA with petty. it took longer for me to type this than to get the FIA/petty.

 

my head is valuable, which is hy i bought a more expensive helmet than necessary.

 

do the maths, is cheaper really better ? i think not ❗

 

Steve

Metalic Black SV-VHPD click here to see our pictures....

[DaveMorris]

Structurally the FIA Bar is an improvement on std Caterham fitting.

Adding the petty strut increases the rigidity of its construction by formation of additional "triangles of safety".

The roll cage is adjudged to be better still, possibly because it has more of these triangles.

I'd say to go for the safest option that you can afford and which is practical.

 

I have roll cage with drivers side, side impact bar. (Can't open the drivers door with this fitted so have to go in thru the roof - but I prefer safety to keeping a dry head)

 

If anyone here can tell me where I could buy one for the passengers side (which does not foul the exhaust) then I'd fit one of these aswell.

[ If anyone does know then pls post or e-mail me ]

[Pete]

Thanks for the positive responses. Please do not get me wrong.........I am not advocating the use of the standard roll bar for competition use as it seems to me that it is more decorative than useful.

I am just a bit concerned over the angle of the FIA bar, but I take on board the comment that Chris made, in that the main frame of the roll bar could well be vertical when the car is upside down. As I have no desire to hang upside down in my harness, I am not going to volunteer to test the theory ❗

I agree that it is essential to use the Petty Strut for competition use, as it triangulates the framework and spreads the loads into the chassis. Its just that on the road, most of us do not fit the strut...............

I might see if I can sort out some figures on the forces involved with the car upside down. Those brackets at the boot end of the braces just look too flimsy to me.

 

What is the concensus on the R500 roll bar? It appears to be more sturdy than the standard bar whilst retaining the same lines (and hood). any thoughts/

 

pete

[scooby dooby doo]

Pete - the FIA bar works fine with the std hood. the tall FIA bar doesn't.

 

Another point - the tall FIA bar is higher than the cage. Does this make it better in anyway 🤔 It gives double the clearance from my head to the likely position of the ground...

 

And finally - I bent my std FIA bar when an oncoming car removed the right hand side front wheel and forced the rear one to bend the dedion into the fuel tank. The back stays distorted about 2" to the left looking from the rear of the car.

 

HOOPY 500 kg R706KGU

[Big Brother]

I am currently having a FIA bar made for a short cockpit seven.

This bar, although produced to the required spec for "FIA", is vertical as oppose to the angled forward design of the long cockpit version.

When I discussed this with the supplier, he mentioned that the "angled" (long cockpit) roll bar is only really effective when the petty strut is fitted.

This is because of the triangulation with the chassis as mentioned above.

 

The upside for me is that the short cockpit FIA bar doesn't need (or come with) a petty strut as it is a more efficient design to start with.

Not that I want to ever test this theory out

 

Steve

 

 

Se7en-Up!

Less is more!

 

[S47zzz]

OTOH I have seen a 7 in a ditch with std bar - the driver did not make it.

This may of course have little to do with whether the car had a 'Standard' or 'FIA' bar.

 

If the car rolls over on anything other than flat ground, the likelyhood of raised ground (eg. a ditch bank when one end of the car drops into it) encroaching into the 'protected' zone between the top of the bar and top of the engine, must be far more significant than the type of bar fitted.

 

When rolling on flat ground the FIA bar may offer better strength, but I'm guessing that it is far more likely that other objects enterring the 'protected' area pose a far greater and more likely threat to the driver fo example parts of another vehicle, hedges, banks, armco, roadsigns, street furniture, etc, etc.

 

[PeterS]

I too am concerned about the weakness of the chassis members taking the loading from the rear members of the FIA bar. Assuming that the car has forward momentum, then the load would tending to be pushing the bar backwards. Fitting the Petty strut would make the strut into a tie, which relies on single shear in the bolt sticking sideways out of the chassis member in the footwell. This doesn't look a particularly strong connection. The other contributors are those flimsy struts at the back of the boot, which would be in compression. The forward angle of the FIA bar would presumably help to get some of the fore and aft component into the stronger chassis members at the back of the cockpit.

The trouble is that prangs come in all shapes and sizes, and a competent design for one type of failure may be unimpressive from another direction. The racing fraternity have been crash testing these cars for a long time now, and Caterham are in the best position to see the results of different defences.

[SLR No.77]

I'm surprised there is so much discussion about the reasoning behing the FIA bar leaning forward - it's blatently obvious if you go back to design principles. Draw a side view of the car. Now position a tube to offer suitable head protection. This will likely be where the top tube of the FIA bar is positioned, as opposed to the standard bar that is rather far to the rear of the car. Now add tubes in order to stabilise and reinforce that top bar, creating the desired protection. No choice, unless you modify the rear end of the car, you need the tubes sloping. And yes, the Petty strut does become an integral part of that bracing. The FIA bar is better than the standard bar due to strength, position and height. But only fractionally better when compared to a bar fitted with a Petty strut - it was designed in the first place to have the strut fitted. The bar was intended for motorsport purposes, not cruising around with the strut missing. Doing so compromises safety for convenience etc, but we wouldn't want to be wrapped in cotton-wool either!

 

Stu.