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Author: Subject: Roll Cages ?
Volvorsport

posted on 27/12/09 at 01:22 PM Reply With Quote
Roll Cages ?

Right , theres no seperate section for roll cages - i think it might be good as a sticky topic since so many questions are asked about MSA specs , road use etc etc .

Anyway , my first question would be .

why not start with the roll cage , then make the chassis to it ?

Does that make it difficult to get certified .

Does the manufacturer of the cage have to install it ?

In a tin top , i can buy a weld incage myself , and it would pass scrutineering - so whats the deal with us locosters ?





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iank

posted on 27/12/09 at 01:43 PM Reply With Quote
The blue book is now, officially, on line here
http://www.msauk.org/site/cms/contentviewarticle.asp?article=646

The regulations regarding roll cage design are in the pdf called "C(c) Competitors - Safety" clicky here

There are lots of diagrams showing cage designs the MSA consider to be appropriate towards the back.

AFAIK so long as the design is certified by the designer (e.g. Procomp) and has it's certificate then it's ok no matter who installs it (providing the scrutineers are happy with the mounting, diagrams also in C(c)).

So I think starting with the cage and designing a chassis around it is perfectly feasible and won't make things harder - but should in theory make it easier as you are starting with a known strong shape.





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JoelP

posted on 27/12/09 at 02:17 PM Reply With Quote
i always thought the chassis and cage should be designed together, madness to do them seperately when you think about it.





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AdrianH

posted on 27/12/09 at 03:01 PM Reply With Quote
Just an update to the links above
http://www.msauk.org/site/cms/contentviewarticle.asp?article=876

Is a link to the 2010 blue book section. Pity it is not one download but lots of smaller ones.
Adrian





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minitici

posted on 27/12/09 at 03:58 PM Reply With Quote
So long as your cage complies with the appropriate drawing in the MSA blue book and the material dimensions and specifications are as per the book, then you do not need 'certification' of the cage.
However if you designed a cage from different spec/size materials or did not follow the drawings then you would need a certificate from the manufacturer to prove that the cage is suitable.
Note also that there are different requirements depending on which category your car comes under. 'Sports Libre' requires larger diameter tubing than 'modified' categories.

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Volvorsport

posted on 27/12/09 at 04:08 PM Reply With Quote
keep the info coming .

so how does a Z cars mini fit in to all this ?





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mark chandler

posted on 27/12/09 at 05:36 PM Reply With Quote
I have made a few cages before which have passed MSA, as above no need to be certified, just make to the rules.

If I made my car again I would build the lower frame, add suitable strengthing plates as defined and build out the roll cage, then hang the upper frame around this.

MSA scrutineers feel for joined metal so design for continous lengths then get someone with a proper mandrel bender to bend the tubes, its very hard to keep everthing in the same plane, so purchase as a preformed to your specification flat pack.

They will also examine the welds and bracing, proper fishmouths required, do not try and fill gaps with weld.

Make sure its high enough for you...

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hicost blade

posted on 27/12/09 at 05:39 PM Reply With Quote
Bolt in cages like the caged type need to be fitted properly on proper welded in mounts to keep the scrutineers happy. The fitting kit supplied with my Westfield Caged cage would have been laughed out of scrutineering. Its best to get someone with experience/manufacturer to fit the cage.
Pro Comp fitted mine, in hindsight I would have got them to make a cage on the car (good old hindsight!!!)

Quite a lot of 'proper' racing space frame chassis are designed/built around roll over/intrusion protection.

Like this DSR chassis, most of these types of car are made completely from CDS or t45 or in the case of this one 4130 aircraft grade seamless tube. This chassis is the protection


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kb58

posted on 27/12/09 at 06:30 PM Reply With Quote
I build the cage first, then welded the rest of the chassis to it. As said above, it's nuts to build the entire car and then bolt on a cage.





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alistairolsen

posted on 27/12/09 at 09:09 PM Reply With Quote
Ok, Ive built a chassis, and fitted threaded bosses for cage mounting feet in the suspension towers. Can anyone advise what I need to do to build an acceptable cage?





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Ben_Copeland

posted on 27/12/09 at 10:58 PM Reply With Quote
quote:
Originally posted by alistairolsen
Ok, Ive built a chassis, and fitted threaded bosses for cage mounting feet in the suspension towers. Can anyone advise what I need to do to build an acceptable cage?


i dont like the idea of Threaded bosses for a roll cage.

Weld it in and it'll be much better.





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Richard Quinn

posted on 28/12/09 at 08:07 AM Reply With Quote
quote:
Originally posted by Ben_Copeland
quote:
Originally posted by alistairolsen
Ok, Ive built a chassis, and fitted threaded bosses for cage mounting feet in the suspension towers. Can anyone advise what I need to do to build an acceptable cage?


i dont like the idea of Threaded bosses for a roll cage.

Weld it in and it'll be much better.
Why? Bolt-in cages can be fine and I've seen some weld-in cages held in with pigeon-shit welding. There is a lot more to it that just the mechanics of the attachment.

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kennyrayandersen

posted on 28/12/09 at 10:38 AM Reply With Quote
Also, keep in mind that when you use a structural fastener that load carrying capability as well as fasteners quality is also is well known (lots of test data and the [high-strength]. So, if you know the load, you can calculate the fastener required (and actually give it whatever margin of safety floats your boat).
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alistairolsen

posted on 28/12/09 at 12:20 PM Reply With Quote
4 off M12x1.5 sockethead cap screws (12.9) on each side of the main hoop so far.

I didnt want to weld it on as id like to be able to remove it in the future if necessary!





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procomp

posted on 29/12/09 at 09:56 AM Reply With Quote
Hi

A few thins to clear up regarding MSA FIA.

If a cage is constructed from 45mm dia tubing that complies with the blue book then anyone can manufacture /fit it. As long as it complies with the MSA/FIA blue book criteria.

However if below the 45mm DIA then for use under MSA /FIA it has to be certificated. which will now cost 2k plus as full crash testing has to take place on the cage and chassis as a combined construction. And then it can only be fitted installed by the manufacturer or the agents who are licenced and registered on the MSA/FIA paper work that goes with that design.

And yes that dose mean that the majority of rollcages being sold in magazines DT Etc Etc are being sold illegally for MSA/FIA use. and the majority of cages sold for kitcars and Westfields in particular are also being sold illegally and the so called certificate and labels are meaningless.

And yes the scrutineers are cracking down on it as has been seen with the majority of MK rollcages being refused at race meetings.

Cheers Matt






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Volvorsport

posted on 29/12/09 at 11:02 AM Reply With Quote
thanks matt ,

given this scenario , of making a roll cage before the chassis is made , as long as its to the blue book specifications , it would appear to be ok .

in the case of it being part of the chassis , ie the uprights where the dash mounts to , and it didnt have any mounting plates at the bottom of the tube , is that part of the chassis or the roll cage ?

i dont want to spend 700 on a cage that doesnt pass scrutineering , so im thinking that i should make a new chassis with the cage incorporated into the design , ie built first .





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hissingsid

posted on 3/1/10 at 08:27 PM Reply With Quote
When making the cage to the blue book, do you need to follow the guidelines and drawings exactly?
I'm thinking of making my own but wish to copy the curved roof bars in the Caterham cages. I know the book says you can have a X brace roff bars, but would curved roof bars be included in that?
Is it a case of read between the lines abit?
If anyone can shed some light on this for me that'll be great!

Graham

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procomp

posted on 4/1/10 at 09:21 AM Reply With Quote
Hi

You need to follow the drawing and text very closely. Roof bars that are not straight ( only certificated cages are allowed to deviate from the drawing in the book ) are part of the reason why so many non certificated cages even in 45mm are being thrown out of MSA events. And the fact that the front legs have two or double bends when the very first section of the text clearly states that this is not allowable. And feet / mountings not being attached as per the MSA FIA criteria. Tubes mounted to chassis rails that are in fresh air with no support.

Cheers Matt






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alistairolsen

posted on 4/1/10 at 10:04 AM Reply With Quote
So this design for instance:




If constructed at home from the required tubing would be unsuitable due to the bends at the base of the A pillars, double bends in the rear loop and curved roof bars to clear helmet tops?

on this one:




the two loops are ok, but again the roof bars present a problem?

But then looking at yours:




The roof rals are curved again?

Id imagine with straight roof rails and the full tubing thickness above your helmet the cage would get very high, the front loop and the rear would need to be close on the same height and to avoid the issues with bends in the cage feet one would have to bring the front legs down inside the cockpit which utterly destroys the legroom?





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iank

posted on 4/1/10 at 10:10 AM Reply With Quote
The last one has a certificate
quote:
http://www.procomp.co.uk/rollcage.html
MIRA have tested and passed the cage, chassis and mountings to FIA requirements.
[and]
The MSA have issued a roll over protection certificate.


You can build what shape you like if you are prepared to pay and have it tested and a certificate issued. If you want to do it without paying you have to follow the rules to the letter.

(just like the rules for SVA/IVA vs what Ford et.al. do).





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procomp

posted on 4/1/10 at 12:21 PM Reply With Quote
Hi

The mountings on the first pic do not comply with MSA.
The other cage with the roof bars clearly do not comply.

The cage shown on our car is fully certificated to the very latest standards which include the mountings and the chassis as a whole structure. It is the only Seven type in the UK to have been through the latest tests.

Cheers Matt






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hissingsid

posted on 4/1/10 at 09:50 PM Reply With Quote
Ok, so I CAN do the curved bars as the Caterham design BUT ONLY if i want to pay for certification. Otherwise I have got to follow the rules to the letter and do a completely straight barred cage.
I wasn't going to have any bends in the front legs as I knew that would be a problem.
Is it ok to add a horizontal bar in the rear hoop at shoulder height for harness bosses?
Too many questions not enough time! It's best to ask these to people that know tho!

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alistairolsen

posted on 4/1/10 at 10:37 PM Reply With Quote
Would the external style of mounting on the blue westfield A pillars be acceptable?





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procomp

posted on 5/1/10 at 07:32 AM Reply With Quote
Hi

Without seeing exactly what chassis structure has been or not added inside can't really say. But if the mounting is as per the caged ones where it is mounted to an unsupported area of chassis with no vertical support and is hanging extensions that have been bolted through the chassis then it dose not comply and will have weakened the chassis to such an extent that the car can not be corner weighted as every time you drive it and place it back on the scales it will read different due to chassis flex.

Cheers Matt






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jeffw

posted on 5/1/10 at 08:55 AM Reply With Quote
OK....so is it possible to retro-fit a cage to something like a Phoenix (which I have) or a Fury and what would the ball park cost be ???






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