speedyxjs
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 posted on 1/5/09 at 07:52 PM |
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Strength of rollbar
No, not a crash vid.
Reading the draft IVA manual (and assume it was the same in SVA), the seatbelt mounts need to be able to withstand a force of 20x your body weight.
I am planning to make my top anchor points on my rollbar tomorrow but am a bit concerned about the fact that there is 8 bolts holding my rollbar to
the chassis (4 each side).
Is this likely to be a fail point due to not being strong enough?
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speedyxjs
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| posted on 1/5/09 at 08:00 PM |
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Cool, cheers 
How long can i resist the temptation to drop a V8 in?
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iank
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| posted on 1/5/09 at 08:55 PM |
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Go up a bolt size if there's enough meat in the plates and you're worried.
I'd agree you should use 8.8 absolute minimum anyway for a roll bar.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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craig1410
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| posted on 1/5/09 at 10:02 PM |
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Go for cap head bolts, they are usually 12.9 grade and not expensive. They also look nicer in my opinion.
Cheers,
Craig.
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HOL
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| posted on 2/5/09 at 07:31 AM |
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My original Tiger one is only two 8mm bolts each side.
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rgrs
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| posted on 2/5/09 at 07:35 AM |
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Does your roll bar have back stays ? If not some testers argue that it's not strong enough to be used for the seat belt mountings.
Roger
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iank
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| posted on 2/5/09 at 09:16 AM |
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quote:
Originally posted by HOL
My original Tiger one is only two 8mm bolts each side.
Sounds a bit of a decorative item.
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Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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brianthemagical
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| posted on 2/5/09 at 09:24 AM |
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Yesterday i was fitting the roll hoop to Surtees TA14, and that was a simple two legged hoop afair, with one 7/16 bolt through each leg and through a
chassis tube inside the leg. Not sure if that makes sence, and they are in double shear, not tension, but it might give an idea.
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Richard Quinn
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| posted on 2/5/09 at 09:38 AM |
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quote:
Originally posted by speedyxjs
No, not a crash vid.
Reading the draft IVA manual (and assume it was the same in SVA), the seatbelt mounts need to be able to withstand a force of 20x your body weight.
I am planning to make my top anchor points on my rollbar tomorrow but am a bit concerned about the fact that there is 8 bolts holding my rollbar to
the chassis (4 each side).
Is this likely to be a fail point due to not being strong enough?
20x what weight? I was always told that some of the strange but definitive
measurements in the SVA were down to the fact that it wasn't only "you" that might drive the car. Get a jockey to present your car
for the IVA?
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craig1410
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| posted on 2/5/09 at 11:00 AM |
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quote:
Originally posted by Richard Quinn
quote:
Originally posted by speedyxjs
No, not a crash vid.
Reading the draft IVA manual (and assume it was the same in SVA), the seatbelt mounts need to be able to withstand a force of 20x your body weight.
I am planning to make my top anchor points on my rollbar tomorrow but am a bit concerned about the fact that there is 8 bolts holding my rollbar to
the chassis (4 each side).
Is this likely to be a fail point due to not being strong enough?
20x what weight? I was always told that some of the strange but definitive
measurements in the SVA were down to the fact that it wasn't only "you" that might drive the car. Get a jockey to present your car
for the IVA?
Don't know about IVA but for SVA they considered a "body weight" to be 68KG's for the purposes of calculating gross design
weight. Personally I think that's a bit light to represent Mr/Mrs average so I'd go with something like 75Kg or maybe even 80Kg.
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Theshed
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| posted on 2/5/09 at 11:38 AM |
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Its quite interesting that most other body protection is designed to give progressively i.e. crash boxes and side impact protection but seat belts
seem to have very little give in then. I thought about this when struggling to decide how to mount my crotch straps. I took the view that I would
rather have the crotch straps pull through about 4 mm of alley than pull through my goolies! javascript:icon(' '
I would worry less about bolts snapping and more about what they are attached to. A big bolt through a small sheet is a waste of space. Many small
bolts may spread the load better than 1 big bolt.
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mark chandler
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| posted on 2/5/09 at 12:19 PM |
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I think it was Colin Chapman that used to quote, you can hang a double decker bus on a 1/4" bolt when people queried his fragile looking F1
cars.
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