macbrew
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 posted on 8/5/03 at 08:11 PM |
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Roll bar spec & bracing
Thinking ahead (months) is there a minimum dia. and wall thickness for the roll bar? thought of using 34mm mild steel gas pipe (easy to bend) or has
it got to be seamless?
I've seen lots of pictures with no bracing and the ones that go rearwards to the top of the flimsy boot look useless if you actually rolled.
Also I've seen pics of an SVA forced bracing that goes forward to the tunnel splitting driver and passenger.
Looked a bit of a tw&t to be honest but the poor guy had to do it.
I'm thinking of plating the bottom rear corners with 3mm and going to about half way up each side on the roll bar, is this OK?
Hope you understand, hard to explain without pics. Any comments welcome.
Tack welding the chassis and floor with no mask just eyes closed gave me sun stroke .... don't be afraid .... be very afraid !!!!!
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Liam
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| posted on 8/5/03 at 08:57 PM |
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Hello. Well done - I only got sunburn and peeling on my face after I spent no more than 10 minutes tacking the bottom of my chassis with no mask
=).
If you ask me, anything 'easy to bend' sounds a bit flimsy for a roll bar! 34mm gas pipe that you could probably bend over your knee
doesn't sound nearly up to the task. I think most people use something in the region of 2" tube with 2 or 3mm wall thinkness, and
definately seamless.
You're right - bracing to the boot frame like cat***ams do does seem a bit pointless - perhaps it's just a cosmetic thing. Where did you
see this 'sva forced bracing'? Sounds a bit harsh - I didn't think you even need a roll bar at all in the SVA. That brace between
the passenger and driver seats is compulsory for the race series but I've never seen it on a road going Locost (except the Hicost actually).
My roll bar's gonna tilt forwards like a cat***ham cos I think it looks much better, and I'll probably add the superficial braces to the
rear for the same reason. I'm sure it'll be strong enough using tube to the aforementioned spec for the main hoop.
Liam
[Edited on 8/5/03 by Liam]
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Liam
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| posted on 8/5/03 at 09:00 PM |
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Oh yeah - your idea of bracing to reinforced rear corners sounds fine to me (for what that's worth) - but why not to the corners of the roll bar
instead of half way up - that would be even better. Matter of cosmetics again I suppose.
Liam
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stephen_gusterson
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| posted on 8/5/03 at 09:15 PM |
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im pretty sure SVA gives min details for a rool bar and bend radius.
get a copy of sva
http://groups.yahoo.com/group/svaonline
its sent to you when you join up
atb
steve
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scutter
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| posted on 9/5/03 at 09:23 AM |
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To quote from the SVA manual
"Roll cages should ideally be manufactured os CDS steel tube dia45mm*2.5mm wall thickness OR 50mm*2.0mm wall thickness. bend radii should exceed
3 times tube diameter"
I made mine from 48mm*4.5mm seamed tubing (using thickness instead of CDS), only cost £18 for 6m. I've braced it to the rear corners of the
chassis, as the sva man said that if the harnesses are mounted to it it needs bracing.
Hopefully heres an attached pic.
All the best Dan.
 
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Marcus
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| posted on 9/5/03 at 08:50 PM |
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macbrew, Roll bar anything like mine?
 
Rescued attachment BACKCHASS1.JPG
Marcus
Because kits are for girls!!
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Neil
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| posted on 10/5/03 at 05:49 PM |
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Roll Bar
Hope this works OK, my first post.
The FIA site at
http://www.fia.com/homepage/selection-a.html
provides links to technical regulations. I think a Locost would be covered by Article 259 - Production Sports Cars (Group CN).
Scroll down to Article 15 "Safety Structures" in Article 259 for rollbar regs.
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Neil
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| posted on 10/5/03 at 06:00 PM |
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Roll bar
Sorry, link should be
http://www.fia.com/regle/appjsomm.htm
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macbrew
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 posted on 10/5/03 at 06:32 PM |
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Thanks.
Scutter and Marcus thanks for the pics, and everybody else for the info.
yeah thats the kind of thing I'm looking at.
I assume there is a limit to the angle forwards / rearwards ... I'll do some research.
I suppose I should get me coat now !
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macbrew
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| posted on 10/5/03 at 06:39 PM |
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Neil, just tried to read the FIA regs. Will comment later when I've been back to college. Why can't they say "IT'S GOTTA BE
BIG AND STRONG"
Cheers anyway.
Forgot me coat.
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