2014 roll cages

[zefarelly]

Apologies if this has been done before, but I'm not too hot at scouring old stuff

I've been contemplating a new better cage for the Cortina . . . . and opened a can of worms, does anyone have an authoritive or informed opinion on what's correct or reality?

with previous design and drawing experience I couldn't help looking at the details and no two websites or documents say the same . . . and App K is contradictory IMO as well

My (perfectly good) ROll centre bolted cage weighs 50kg . . . . .

there is 13m of tubing in there . . .

Good old CDS tubing weighs on average 7.85kg/m2 at 1mm thick (7850/m3)

you use, acceptable FiA sized tubing could vary by over 20% ( using cross sectional areas.

13m of tubing could be 12kg or just under 15kg . . . . 20% difference

I'm not looking for ultralight and potential danger, but 15kg of tubing to a 50kg cage is a considerable difference, and a welded cage would be stiffer, lighter and look better if bespoke. . . hence the investigation.

[Teddington Ted]

Originally Posted by zefarelly

Apologies if this has been done before, but I'm not too hot at scouring old stuff

I've been contemplating a new better cage for the Cortina . . . . and opened a can of worms, does anyone have an authoritive or informed opinion on what's correct or reality?

with previous design and drawing experience I couldn't help looking at the details and no two websites or documents say the same . . . and App K is contradictory IMO as well

My (perfectly good) ROll centre bolted cage weighs 50kg . . . . .

there is 13m of tubing in there . . .

Good old CDS tubing weighs on average 7.85kg/m2 at 1mm thick (7850/m3)

you use, acceptable FiA sized tubing could vary by over 20% ( using cross sectional areas.

13m of tubing could be 12kg or just under 15kg . . . . 20% difference

I'm not looking for ultralight and potential danger, but 15kg of tubing to a 50kg cage is a considerable difference, and a welded cage would be stiffer, lighter and look better if bespoke. . . hence the investigation.

Joe

I've just used Andy Robinson for the cage in my Standard 10. He is excellent and can answer your questions.

Mark

[terence]

Roll Centre stuff was always a bit on the heavy side Zef.You could always give Sonny Howard a call,he works very closely with the powers that be,he is possibly the best choice, SHP at Littleport Cambridgeshire should bring up his sight. Sounds to me that you might start looking at 3mm T45? Main hoop should be about a third of the one you have!

[Clive Brown]

I think this is a Very Bad Idea indeed. T45 derives its strength from being more springy, which makes it useless for a structure (your rollcage), the primary purpose of which for competition purposes is to make the shell more rigid, so that suspension settings, rather than body flex, determine the handling characteristics.

I have first-hand experience of a spaceframe Special Saloon built with T45 in the interests of weight saving which flexed like buggery, and was dysfunctional as a consequence. Its replacement was built with T25, which was some 40lbs heavier at about 8cwt. 45lbs, but handled properly.

Use CDS T25 tube, to the minimum thickness that your series regulations allow, but fix it as near to the suspension mounting points as your series regulations permit.

Can you run extra tube between the various mounting points of the cage?

Just as an afterthought, it is also generally consider a Good Idea if the rollcage offers some degree of protection to your bonce should you be so unfortunate as to invert the car in the course of competition....

[morninggents]

I think the MSA has had a bit to say about roll cages for 2014 and most of our HSCC race series have had to alter their technical regulations for this year. Should all be in the latest 'Blue Book'. App K doesn't allow as many fixing points as latest MSA specs, I understand.

[Clive Brown]

So how does this square with App. K cars running at an MSA-sanctioned event?

[terence]

Originally Posted by Clive Brown

I think this is a Very Bad Idea indeed. T45 derives its strength from being more springy, which makes it useless for a structure (your rollcage), the primary purpose of which for competition purposes is to make the shell more rigid, so that suspension settings, rather than body flex, determine the handling characteristics.

I have first-hand experience of a spaceframe Special Saloon built with T45 in the interests of weight saving which flexed like buggery, and was dysfunctional as a consequence. Its replacement was built with T25, which was some 40lbs heavier at about 8cwt. 45lbs, but handled properly.

Use CDS T25 tube, to the minimum thickness that your series regulations allow, but fix it as near to the suspension mounting points as your series regulations permit.

Can you run extra tube between the various mounting points of the cage?

Just as an afterthought, it is also generally consider a Good Idea if the rollcage offers some degree of protection to your bonce should you be so unfortunate as to invert the car in the course of competition....

Been good enough since we used it for Clelands winning car in 95.

[Clive Brown]

Originally Posted by terence bower

Been good enough since we used it for Clelands winning car in 95.

Maybe, but weren't those cars allowed a rather more complex structure than the sort of thing Zef is talking about?

[zefarelly]

I want something legal and safe . . . the weight saving should be a bonus

The Roll centre cage fits and works, theres no need to change it, but, whilst I know 15kg of tubing will get heavier with fitting, 50kg is a lot, also bolted cages flex

I'm looking to:

decrease visual impact of the cage, for historical aesthetics.
maintain safety: I have no death wish

weight saving and structural rigidity should be happy accidents/by products of the process.

6 point and door bars . . . If I wanted a WRC car I wouldn't have a MK1 Cortina

[terence]

In that case speak to Sonny, he doesn't bite.Very pleased with the six point bolt in he did for me, tell him what you would like, if it complies, he'll do it.

[Peter Mallett]

Originally Posted by zefarelly

I want something legal and safe . . . the weight saving should be a bonus

The Roll centre cage fits and works, theres no need to change it, but, whilst I know 15kg of tubing will get heavier with fitting, 50kg is a lot, also bolted cages flex

I'm looking to:

decrease visual impact of the cage, for historical aesthetics.
maintain safety: I have no death wish

weight saving and structural rigidity should be happy accidents/by products of the process.

6 point and door bars . . . If I wanted a WRC car I wouldn't have a MK1 Cortina

A company called Caged built my last one in the Capri (changed due to MSA requirements) and has installed a bespoke cage in the Rover which replicates the original cage that we had to remove. It does have a couple of additional bars but otherwise looks the same.

[zefarelly]

The original Cortina cage from 64 wouldn't pass anything. I have an original Aley bars cage in a lock up too, with Aluminium clamps!

Kim at HRP has done cages in the past for me and I'll almost definitely go back there, I was more wondering about tube sizing and methodology . . . .T45/Tig seems to be out of the picture now.

haven't got this years blue book yet as haven't bothered renewing my license!

[Peter Mallett]

Well, if you have a preferred supplier I struggle to understand why you'd ask the question? Most of us work on the basis of trust, so if your supplier has helped before, I'd go back again.

I stress this is not my professional opinion, which tends towards the contract rules, but when it comes to my racing, I work on the basis of trust.

[terence]

Originally Posted by zefarelly

The original Cortina cage from 64 wouldn't pass anything. I have an original Aley bars cage in a lock up too, with Aluminium clamps!

Kim at HRP has done cages in the past for me and I'll almost definitely go back there, I was more wondering about tube sizing and methodology . . . .T45/Tig seems to be out of the picture now.

haven't got this years blue book yet as haven't bothered renewing my license!

Tube size for main hoop is as it has been for quite some time- 50mm and nothing less than 43mmfor everthing else.Pretty sure the wall thickness is 4mm. T45 you are allowed to go down to 2mm for the main hoop-your able to trim the ends with tin snips.Dont see how your going to lose weight by using original thickness though.

[morninggents]

Originally Posted by zefarelly

haven't got this years blue book yet as haven't bothered renewing my license!

I have a spare. Let me know and I will post it tomorrow.

[Serge]

Originally Posted by terence bower

Tube size for main hoop is as it has been for quite some time- 50mm and nothing less than 43mmfor everthing else.Pretty sure the wall thickness is 4mm. T45 you are allowed to go down to 2mm for the main hoop-your able to trim the ends with tin snips.Dont see how your going to lose weight by using original thickness though.

Sorry if this is a silly question, but I would like to some clarification because I'm doing some research myself for my rollcage.

Are these tube sizes that you mention (50mm - 43mm) for MSA rules? Because when you read the ROPS section of the 2014 AppK regulations it seems that from periods F up to G2 you are allowed to use a minimum of 38 x 2.5 or 40 x 2.0 for everything (main hoops, laterial bars). (FWI, 40x2.0 is quite a bit lighter than 38x2.5, about 0.4kg per meter.)

Am I missing something in the regulations? Or do you need to build a cage that complies with both MSA and FIA regulations if you are homologating your car in the UK?


Kind regards,

Serge

[terence]

Hi Serge, as far as I know, the size quoted was from FIA so the MSA would have addopted those sizes as a matter of course.The size spec was altered some time ago now. Hope that helps.

[Tel 911S]

http://www.safetydevices.com/motorsp...m+tubing+rule/

Link to guide of new cage specs . You can use an old [ 38 mm ] main hoop size if the whole cage has a certificate . If it is a new build cage it has to be to the new dimensions in the Blue book

[zefarelly]

Serge, Thankyou, the foorst person to understand my question!

my old cage has a 2" main hoop and 1.625" everything else, its heavy! and I doubt its any stronger due to its construction, as a concequence

I did discuss with HRP, but they're fabricators not metallurgists. as a design engineer by (previous) trade I can't help but look into the options.

as far as I read APp K allows period F to have on of 4 tube sizes all over, no requirement for a 2" main hoop.

The grey area appears to be T45 and TiG welding so I'm not going there, CDS is reliable and safe and light enough if you get the detail right.

I'm thinking 40mm x 2mm throughout.

Peter . . .If you could copy and paste the cage section and email it from the blue book CD I'd be appreciative, I will renew my license in due course but currently have nothing to drive! I'm assuming its a copy of App K.

[midgetman]

Zef, the BB is online these days at the MSA web site.

HTH

M

[Serge]

That's what I meant, Joe! I don't know the regulations regarding T45 but as far as welding is concerned: (App K)

1.2.3.3.5 Welding instructions

This must be carried out along the whole perimeter of the tube. All welding must be of the highest quality possible with full penetration (preferably arc welding and in particular heliarc).

....


So they don't specify a particular welding process, but prefer TIG (heliarc).

[zefarelly]

In my old drawing office days I used to come across drawings from the 50's and 60's with 'WELD STRONGLY ALONG RED LINE'

It was around the time I could pretty much recite all 3 parts of BS308 and BS499 for welding procedure and symbols . . . proper drawing, on film with pens and pencils!

[SAMD]

Apparently Adrain Newey (Spelling!) still uses a drawing board. One of the only designers to do so

[zefarelly]

I've been looking for one for my workshop, just for getting ideas down, sketching and visualising, computers are crap for that.