Moorron
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| posted on 8/2/07 at 09:59 PM |
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Roll over hoop question
Been looking about at work and with the kitcar on my mind im looking at making a spare rollover hoop as we have some custom extrusion and a cnc
bending machine for it. its a section 115mm x 25mm and has nice full radius on the ends so looks 'aero dynamic and sleek. It has the added
advantake of a slot on the inner edge so u can bolt a camera, high level break light or to bolt on support for the rear tub, My question is....
Would it be a 'safety' issue if u knew it wasnt strong anuff incase of a roll over?
might go off and model it up in solidworks to see what it would look like.
Sorry about my spelling, im an engineer and only work in numbers.
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Hellfire
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| posted on 8/2/07 at 10:45 PM |
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You don't actually need a roll over hoop at all,  so it would only be a 'safety' issue for you. It basically comes down to
whether you are prepared to take the risk.
Personally, if it looked really good, I would take the risk but thats just me. No doubt others will think that's foolish 
Phil
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iank
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| posted on 8/2/07 at 11:04 PM |
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What material is it? If it's aluminium it will just be decorative. If steel then you will need an engineer to tell you if it's actually
up to being rolled on.
As Hellfire suggests it's your head if you flip the car. It certainly won't be suitable for any motorsports whatever you do.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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macnab
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| posted on 9/2/07 at 05:26 AM |
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Fit a proper bar. This is one thing missing from the SVA as it's just as important as the seatbelts. Remember it's not just for you but
your passengers as well, how would their family feel if their loved ones died because someone couldn't be bothered fitting a critical safety
device?
[Edited on 9/2/07 by macnab]
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bartonp
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| posted on 9/2/07 at 09:35 AM |
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I wonder how many road cars end up on their roof? Can't really quantify the risk without knowing this. Gut feel says that it's far more
likely in motorsport.
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iank
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| posted on 9/2/07 at 09:50 AM |
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Seen 3 cars on their roofs over the last 2 years.
Metro with a silvertop still strapped in (was on the bus so couldn't help, but there was already a crowd) it couldn't have been doing more
than 40mph on a stretch through a village (Waterbeach off the A10 ourside the post office for those that know the area) so I have no idea how
she'd done it.
Saxo (with 4 dazed but unhurt teenagers) probably caused by too much speed into a greasy corner by the distance it had gone on its roof, stopped and
ambulance/plod already arrived while I was asking if there was anyone trapped.
3rd was on the motorway, couldn't recognise the car and firemen were busy cutting the driver out. 
It's actually fairly easy to flip a car, just need to hit a curb fast at the right (wrong) angle. Though you're absolutely right it
happens far more in motorsport.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Hellfire
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| posted on 9/2/07 at 09:55 AM |
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But where do you stop? Only you can decide what a critical safety device is? By law, you have to wear a seatbelt and therefore needs to be an
SVA requirement. There is no law that states you have to fit a rollbar.
Even if you've got one fitted, how do you know the roll bar is going to be sufficient, should you be unfortunate enough to find youself upside
down in an accident? What's to say it won't snap off at the first sign of impact?
If it's safety you're after, then either fit a full cage or don't build a seven at all, cos by design they just aren't safe.
Which manufacturers carry out crash tests on sevens to ensure our safety?
Anyone who builds a seven must have considered the risks involved and felt comfortable taking those risks. If anyone feels comfortable driving around
with an insufficient rollbar or even without a roll bar, then why not? It's a personal choice. Some people even ride
motorcycles.................
Phil
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nick205
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| posted on 9/2/07 at 11:08 AM |
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quote:
Originally posted by Hellfire
Anyone who builds a seven must have considered the risks involved and felt comfortable taking those risks. If anyone feels comfortable driving around
with an insufficient rollbar or even without a roll bar, then why not? It's a personal choice. Some people even ride
motorcycles.................
Phil
I agree that it comes down to personal choice as to whether to fit a roll bar and whether that rollbar is considered sufficient for it's
purpose. I got MK to weld mine on to the chassis as I wasn't comfortable with the idea of bolting it on using rivnuts. I now wish I had got
them to weld in some rear braces between the rollbar and the lower rear section of the chassis, but the car's built and I've made up my
mind to live with it.
IMHO riding a motorbike is different in that you are not strapped to it and therefore will tend to part company with it in the event of a crash. This
means you won't have ~4-600kg of car trying to dismember you as it drags along the ground.
Personally I consider riding a bike on the road too greater risk to my well being
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jimgiblett
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| posted on 9/2/07 at 12:21 PM |
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quote:
Originally posted by Hellfire
Which manufacturers carry out crash tests on sevens to ensure our safety?
Phil
Not quite a seven but Fisher Sportscars have TUV approval on the Fury.
I know how much you invest in safety is a personal thing (Nanny State and all) but do we want to leave everything to Darwin selection? .... thinking
about it ......maybe we do
[Edited on 9/2/07 by jimgiblett]
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David Jenkins
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| posted on 9/2/07 at 12:46 PM |
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I know someone who's flipped a Caterham 7 - and walked away thanks to his competition cage.
I'd vote for a minimum of a basic hoop, properly braced. Apart from anything else, it gives you somewhere to mount the top fixings of your
harness.
David
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iank
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| posted on 9/2/07 at 12:49 PM |
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re: crash test. Caterham
To talk about safety you really need to think of both active and passive safety.
A 7 can out brake, out accelerate and out maneouver just about anything on the road, so it's active safety (i.e. ability to avoid an accident)
is very good.
Passive safety (ability to survive once an accident has happened) is good if you just have an off as the chassis is strong and the bonnet long.
However if you hit/are hit by a 2 tonne 4x4 things aren't as good in a 500kg car of any kind.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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macnab
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| posted on 9/2/07 at 02:14 PM |
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I have seen 2 cars on their roof in the last 6 months just at the top of my drive. It doesn’t take much to flip a 500kg car and most who drive these
things drive quite enthusiastically. I’m not saying you need a full cage just a simple robust bar that will not spoils the looks of this type of car,
it’s a race car design anyway. If may be light but for the brief second your still alive with the whole thing sitting on your bonce while getting
sanded by the road, I’m sure you’ll think ‘Bugger I wish I’d fitted that bar…’
[Edited on 9/2/07 by macnab]
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