After my slight hijack (sorry boggle) of this thread yesterday, I need to find out if i need to add supports to my roll bar and how i might make them. I assume i can fit them to the top chassis rail that goes round the top at the rear?

Here is a pic of my roll bar as is:



It is bolted on with 6 bolt (3 either side) is that makes any difference.

The rear hoop on the chassis is not structural, merely a support for the ally rear panel. You really need to go to the bottom rear corners of the chassis to get any benefit.

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Originally posted by Marcus
The rear hoop on the chassis is not structural, merely a support for the ally rear panel. You really need to go to the bottom rear corners of the chassis to get any benefit.

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caterham dont, goes to the top
as ive got one now

drill four holes in your fuel tank - one top and bottom each side. Problem sorted, the braces can now brace the hoop

I think the main issue as far as IV Ais concerned is if you intend to mount your harnesses to it? That's the only thing I can find reference to anyway unless someone would care to correct me?

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Originally posted by eznfrank
I think the main issue as far as IV Ais concerned is if you intend to mount your harnesses to it? That's the only thing I can find reference to anyway unless someone would care to correct me?

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roll bar isn't needed for IVA - seat belt mounts that are high enough and can take the force in the examiners view are needed.

as far as i can tell, the roll hoop isn't a requirement, but makes good sense to have.

going by that, i don't think supports are essential, but without them, the roll hoop is pretty much useless.

have you got a photo of the back of your chassis with no body on it?

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Originally posted by blakep82
have you got a photo of the back of your chassis with no body on it?

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Contact rgrs he was the one that failed sva for not having supports on his rollbar. Why go to the bother of fitting a rollbar and not bracing it.

Hi,Ive looked through the iva manual and cant find anything about needing a roll bar
the thing is your using it for seat belt mountings so then it has to be considered strong enough so rear bracing may be necesary
just another point do look at the iva manual to ensure the correct placing of the seat belt mounts as i put mine where i thought and then read the manual and find i have to move mine 10mm
as for a roll bar without supports i guess it depends on how tall it is and how its mounted and what its made of that counts
im sure ive seen cobras with hoops and no braces are these just for looks?
Ray

[Edited on 8/2/10 by RAYLEE29]

hmm, can't seem to upload photos to the archive... i've draw on your picture what i think you should do. hang on...

here we go


silver grey is the support, it might get in the way of the fuel tank bar (green), but if you were to cut it, and weld it back onto the hoop support (may not be accepted by IVA though as if you do roll, the tank will be affected) so the other option is, to re-do the fuel tank bars.

i think your fuel tank bars might be a bit more complicated then they need to be. you could probably get away with just a triangluar bar up as they already are, and back down again

[Edited on 8/2/10 by blakep82]

Dax dont fit roll bar supports.

I believe the quantum extreme doesnt have them either
Ray

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Originally posted by cd.thomson
Dax dont fit roll bar supports.

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is the roll bars on dax and westfields etc welded in as part of the chassis, rather than bolted on though? i'm 'guessing' ( ) the roll hoop on these goes all the way from the floor up aqnd over with all other chassis tubes welded to it? i can see how that would work ok.

The westfield I helped build had that simple hoop rollbar. Too low for occupants and no supports. Oh and it was just bolted on.

I am in the same boat as the OP with the same style rollbar (MK). So am also interested if I leave as is for the IVA how hard is it to add a full cage afterwards?

Rich

Here is a picture of my roll bar supports; you can just see that they drop down either side of the fuel tank. I personally wouldn't drive a car with a roll hoop that has no supports, as in the event of an accident they are likely to just fold back on themselves (just my opinion)