Rollcage advice

[jamie_1992 66 1 Cars]

I’m looking for some advice on rollcages for my 205, I currently have a bolt in safety devices c44 cage in the car but wanting to upgrade.

My options are:

a) modify my current cage to include braces to the front struts and extra bracing

b) remove current cage and fit a full blown weld in cage from custom cages 

 

I believe the custom cages weights around 33kg and not sure what the c44 weights but I’d imagine the weld in weights more as there is more to it, what I’m wondering is will the added weight of a weld in cage be worth it for the added strength it would give to the shell 

 

Edit: just found that the c43 the full bolt in cage weights 60kg according to the safety devices website so I’m not sure how the custom cages can be nearly half the weight, think il have to research this a little more 

 

Current cage http://www.safetydevices.com/motorsport/products/roll-cage/Peugeot+205+-1983-1998-3-door-without-sunroof/82/925/

 

Custom cages https://www.customcages.co.uk/roll-cages/peugeot-205

Edited November 18, 2018 by jamie_1992

[Biggles 65]

2 hours ago, jamie_1992 said:

Edit: just found that the c43 the full bolt in cage weights 60kg according to the safety devices website so I’m not sure how the custom cages can be nearly half the weight, think il have to research this a little more

 

Custom cages https://www.customcages.co.uk/roll-cages/peugeot-205

 

 

If you read the link you posted you'll find out - the CC cage is certificated rather than to Blue Book dimensions.

 

 

[jamie_1992 66 1 Cars]

Is a weld in cage not certified then? 

[Batfink 201]

I guess the first question is what are you wanting the car to be able to do. This will determine what cage will be able to be used. A lot of the Peugeot 205 cages are effectively 'old hat' - using smaller tubing and not necessarily meeting current regulations for racing (though they can get historic exemptions.

Whatever the case a descent weld in cage is never cheap so adding to what you have may be the most cost effective if you can get away with it.

 

[jamie_1992 66 1 Cars]

2 hours ago, Batfink said:

I guess the first question is what are you wanting the car to be able to do. This will determine what cage will be able to be used. A lot of the Peugeot 205 cages are effectively 'old hat' - using smaller tubing and not necessarily meeting current regulations for racing (though they can get historic exemptions.

Whatever the case a descent weld in cage is never cheap so adding to what you have may be the most cost effective if you can get away with it.

 

Although I am not competing in the car yet it’s something I would like to do in the future so would be better to get it done right the first time and as the car is virtually striped at the moment it seems a good time to get it sorted. 

 

[mmt 15]

I Would get a new cage with a certificate. On a bad Day Scrutinering might want to discuss weld quality/non-compliance due to additional tubing. 

 

In My book you should forget about weight when it comes to cages. 

 

Definately Go for a cage to the front turrets. 

Edited November 19, 2018 by mmt

[SweetBadger 94]

A homologated cage should be fine for competing (inc your c44  cage) provided it is installed to a good standard. You'll need the homologation sticker on the cage, and certificate in case a scrutineer takes a disliking to you (I have never been asked to provide this).

 

The problem is, the only permitted modification that I'm aware of to a homologated cage is the addition of a harness bar. Any other mods (like braces to the front struts) will invalidate the homologation, so if you want to do that, rip it out and start again with a custom cage built to current MSA regs.

[welshpug 1,657]

if weight is a concern then get a higher quality tubeset, custom cages usually offer two types.

[Biggles 65]

SweetBadger is correct - you can use a C44 as is but adding braces to the front towers is a no-no. 

 

For the number of tubes in it, I suspect the quoted weight of the CC cage is for the T45 version.  Were you planning on doing the installation yourself ?  I ask as welding T45 isn't the same as welding CDS and to get CC to give you the certificate I believe you have to do a weld sample.   As mmt says, forget the weight (unless your are genuinely aiming to be at the sharp end in which case maybe a 205 is not the best starting point...) and go CDS.  If you were going to get CC to do the installation, I'd suggest looking around as when I had a cage made 5-ish years ago, CC were by far the most expensive quote I got (50% more than I ended up paying in fact).  (Dave at Tornado Motorsport near Derby does a cracking job btw.)

[jamie_1992 66 1 Cars]

Thanks for the replies, yes I will be doing the install myself and think I’m going to get a new weld in but might see what other are available first 

weight is not a massive concern if it results in a stiffer shell but I’m wondering how one can be nearly double for a similar cage 

 

[Biggles 65]

Because the T45 cage will be about half the wall thickness of the CDS.

 

As an example - MSA minimum requirements are 45x2.5mm CDS - a friend's T45 cage is 38x1.5mm ...

[welshpug 1,657]

yep, the material is stronger so the minimum tube od and thickness is smaller.

[Kane 34]

Yep, yield strength of T45 is almost double that on CDS tube (~680 MPa vs ~380MPa) so you can get away with a significantly smaller/thinner cage while maintaining an equivalent strength. 

 

I wouldn’t bother with T45 if competing is something you may or may not end up doing further down the line. The reason being is that if you build a cage using T45 of a lesser diameter/wall thickness than listed in the blue book you require a test certificate from an approved body (Mira is the only company in the UK that can provide). This will not only cost you more than the cage itself but you have to provide the 3D model for them to analyse which unless you can do yourself is more expense. 

 

Stick with the cheaper material using the minimum dimensions noted in the blue book to simplify things. 

 

Edit: beat me to it WP

Edited November 19, 2018 by Kane

[welshpug 1,657]

blue book does specify tube sizes for t45 also.

[Kane 34]

Not that I’m aware of. Section K only specifies a minimum material composition, strength and associated dimensions (CDS, 350MPa and dims depending on tube type - mandatory/optional and year of approval). 

Edited November 20, 2018 by Kane

[Biggles 65]

19 hours ago, Kane said:

I wouldn’t bother with T45 if competing is something you may or may not end up doing further down the line. The reason being is that if you build a cage using T45 of a lesser diameter/wall thickness than listed in the blue book you require a test certificate from an approved body (Mira is the only company in the UK that can provide). This will not only cost you more than the cage itself but you have to provide the 3D model for them to analyse which unless you can do yourself is more expense.

Except Custom Cages are advertising the cage as certificated so they have already had the analysis done.  All you would have to do is satisfy CC you've fitted it correctly in order to get the certificate.

Mira do indeed know how to charge - IIRC the analysis for the cage in my friend's car cost a 4 figure sum ... 

Edited November 20, 2018 by Biggles

[Kane 34]

Sorry I hadn’t realised he was looking at a certified cage as he said he was intending on making it up himself. 

 

You’re not wrong! Plenty Hillclimb/sprint cars been done over in recent seasons due to lack of rule enforcement/blue book ambiguities, a lot of which have run into the thousands to rectify. 

[Batfink 201]

On 11/19/2018 at 10:12 AM, mmt said:

 

 

In My book you should forget about weight when it comes to cages. 

 

Have to say I disagree! I got a custom made cage and we developed it to be light and strong. It could be stronger but theres a point where the gains of adding more triangulation meet diminishing returns and if you dont need it, dont have it...


As for T45. Im sure I checked out the Custom Cages version for the 205. Its not a homologated cage so its a thicker wall thickness than the super lightweight ones. I'd check before buying!
In the end I went CDS as the minor weight improvement vs cost was not worth it.

The modern tube sizing looks so much better in the car than the old thin diameter cages

[Biggles 65]

1 hour ago, Batfink said:

Have to say I disagree! I got a custom made cage and we developed it to be light and strong. It could be stronger but theres a point where the gains of adding more triangulation meet diminishing returns and if you dont need it, dont have it...

But isn't that more a 'don't add unnecessary tubes' rather than a specific weight issue ?  Do you need two diagonals between the backstays as well as two in the main hoop ?  Do you need an X in the roof ?  Do you need twin door bars ?  Pit props - if you don't need them because your door aperture is narrow enough then don't put them in - they are a complete PITA - if anything they impede your ability to get out in a hurry - been there, tried that.  Etc.

Edited November 20, 2018 by Biggles

[jamie_1992 66 1 Cars]

It’s not the weight I was too worried about, what I wanted to know was would the benefits of having a stiffer cage with better bracing out weight the disadvantages of the extra weight? 

But as others have pointed out using a lager diameter but thinner wall tube is lighter than what I have now, so a new cc  cds cage (32kg)  may actually come in lighter 

[Kane 34]

Increasing the torsional stiffness of the chassis is going to dramatically reduce any unwanted changes in steering geometry which I would say is the desired goal over a small increase in weight. There is however more steps to take to try and reduce the front end swinging about when loaded up.

 

Tying the strut tops back into the cage and then triangulating back to the bulkhead somehow, reinforcing the subframe/pick up points etc. All help with keeping things in the correct position. I’m pretty certain that for competition use you’re not allowed to pass the additional bracing through the bulkhead though so this needs to be isolated (Bolted/welded end plate onto bulkhead with the same on the other face). 

 

@Batfink did you have your cage assessed by Mira or other? I’m sure I’d be able to model up and analyse a cage myself if I could get a copy of solid works/Catia etc. but I don’t know what the input parameters need to be I.e. load values and points of application, design factors of safety for the loads, deflection limits etc. There doesn’t seem to be a design guide that I can find with all the parameters that are checked. 

[Batfink 201]

On 11/21/2018 at 8:46 AM, Kane said:

Increasing the torsional stiffness of the chassis is going to dramatically reduce any unwanted changes in steering geometry which I would say is the desired goal over a small increase in weight. There is however more steps to take to try and reduce the front end swinging about when loaded up.

 

Tying the strut tops back into the cage and then triangulating back to the bulkhead somehow, reinforcing the subframe/pick up points etc. All help with keeping things in the correct position. I’m pretty certain that for competition use you’re not allowed to pass the additional bracing through the bulkhead though so this needs to be isolated (Bolted/welded end plate onto bulkhead with the same on the other face). 

 

@Batfink did you have your cage assessed by Mira or other? I’m sure I’d be able to model up and analyse a cage myself if I could get a copy of solid works/Catia etc. but I don’t know what the input parameters need to be I.e. load values and points of application, design factors of safety for the loads, deflection limits etc. There doesn’t seem to be a design guide that I can find with all the parameters that are checked. 

No way could I afford Mira lol 
I was all set for having T45. Then I got the explanation of the differences between a T45 cage and a Homologated T45 is. We had a discussion about whether the cost of using thin T45 to get a true noticable difference in weight vs CDS and getting it tested was financially worth it. For what I'm doing sticking with CDS and complying to current MSA rules suited my wallet better. We got to a point where it was stiff enough and light enough for what we are trying to achieve with the car.

But regarding the OP's car Even welding in a similar design to whats fitted now should make a difference on chassis stiffness vs bolt in.

 

[camgti 56]

Just to throw in my 2 cents here.

 

I have recently completed a a full blown race build. If something is worth doing, do it once. Go and take the car to someone who can give you advice if they are doing the work. Have a look at the requirements for ANY future events you may like to do. Build the cage around that. 

We wanted safety to be first and stiffness second so have a heavier cage. Car is also seam welded.  It has cross sections ontop and on the back stays and doors. It has 2 A pillar bars and triangulates to the front turrets. 

 

Have it made for quality and safety and you cant really go wrong. A few more bars could save your life. Lets face it, we are not racing for sheep stations at the end of the day so a little extra weight will soon be forgotton. 

Edited February 12, 2019 by camgti