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<  Newcomers  ~  Question about Twingo roll cage

PostPosted: Sat Jun 21, 2014 1:10 pm
Posts: 5Joined: Thu Jun 19, 2014 8:52 pm
Hi Everyone.

I have a Renault RS133 which I fancy sprinting/hill climbing. Being as I have adjustable strut tops and no rear seats, I would be in a modified class, 1600cc somewhere just under 1000Kg and 160hp which i think is B2 catagory, so needing some roll protection.

Image

Not wanting a full weld in cage, but meeting the regs for mounting points has ruled out the ones that are available at present. So, it would mean getting a hoop bent and tubes cut etc as a DIY job. That's not a problem as there's an engineering company next door that does fabrication work.

Foot plate reinforcement plates for the main hoop will be welded in and then, main hoop bolted down, as per the book also thinking of bolting to the b-pillar upper seat belt mount

Rear arches will get reinforcing plates welded in, then rear stays with cross and harness bar bolted as per the book.
Question is, is it acceptable to use the OMP gudgeon pin connectors to attach rear stays x harness bar to the top of the main hoop?

Thanks
Neil


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PostPosted: Sat Jun 21, 2014 8:57 pm
Posts: 270Joined: Wed Apr 23, 2008 1:10 pm
The MSA Regs are here http://msauk.org/uploadedfiles/msa_form ... rs_(Safety)_(K).pdf

Quote:
1.3.7. Removable Members. Should removable
members be used in the construction of a ROPS, the
demountable joints used must comply with an
approved type (see drawings K21 to K30). The screws
and bolts must be of adequate diameter and of ISO
Standard 8.8 or better. FIA homologated demountable
joints are also permitted.

Demountable joints must not be used as part of a main,
front or lateral rollbar because they act as hinges in the
principal structure and allow deformation. Their use is
solely for attaching members to the rollbars and
for attaching a lateral rollbar to a main rollbar (see drawing
K2). In this last case, hinged joints in drawings K21 to
K30 must not be used.


Hinged jonts would not be acceptable, but there are others that would. See the drawings listed to compare with what you intend to use.



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Renny Thomson

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PostPosted: Sat Jun 21, 2014 9:19 pm
Posts: 5Joined: Thu Jun 19, 2014 8:52 pm
Yeah, ive been wading through the safety section and wondered about the interpretation of the bit you highlited about hinged joints and the main roll bar.
Thing is, I know the Megane R26r factory fit half cage has these, where the rear stays bolt onto the main hoop and I was thinking of doing a simillar layout but incorporating a harness bar.
Image
Hence being slightly confused


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PostPosted: Mon Jun 23, 2014 7:36 pm
Posts: 270Joined: Wed Apr 23, 2008 1:10 pm
Is the Megane cage homologated, or certified? Possibly not.


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Renny Thomson

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PostPosted: Mon Jun 23, 2014 9:13 pm
Posts: 5Joined: Thu Jun 19, 2014 8:52 pm
Scottish Scrutineer wrote:
Is the Megane cage homologated, or certified? Possibly not.


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Im not sure what standards (if any) the Meg cage is built to.

No problems, it looks like its going to be saddle clamps instead as they are definitely in the book. Unless you would recommend a better alternative which can be seperated when/if needed.

I will try to get across to Boyndie on 5th or 6th to have a good look about and chat :)


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PostPosted: Tue Jun 24, 2014 7:16 am
Posts: 270Joined: Wed Apr 23, 2008 1:10 pm
singlespeed wrote:
Scottish Scrutineer wrote:
Is the Megane cage homologated, or certified? Possibly not.


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Im not sure what standards (if any) the Meg cage is built to.

No problems, it looks like its going to be saddle clamps instead as they are definitely in the book. Unless you would recommend a better alternative which can be seperated when/if needed.

I will try to get across to Boyndie on 5th or 6th to have a good look about and chat :)

It is difficult to find an acceptable compromise to have de mountable members that are of adequate strength and stability. Why do you need to remove the members?


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Renny



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PostPosted: Tue Jun 24, 2014 7:41 pm
Posts: 5Joined: Thu Jun 19, 2014 8:52 pm
Its still my road car, so having the option to have a usable rear boot space may be handy. 8-10 bolts for the stays, Vs a full strip to remove the rear cage


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PostPosted: Fri Jun 27, 2014 8:09 pm
Posts: 5Joined: Thu Jun 19, 2014 8:52 pm
Thinking about it, I could have the rear stays welded to the top of the main hoop. Then have a demountable X complete with harness bar fixed onto the rear stays. Depending on the position of the harness bar within the X, that could be four or six attachment points.


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PostPosted: Thu Jul 10, 2014 7:55 am
Posts: 270Joined: Wed Apr 23, 2008 1:10 pm
Removable diagonals were quite common in dual use cars as they allow use of the rear seats.


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Renny



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