Cage material

I will be adding a cage to my XR soon and want to know the common diameter material used and legal for events. I have searched around some rule books and it looks like I'm supposed to use some gigantic 1 3/4 Dia..095 wall tubing. I would prefer to use 1 1/2 Dia. if possible. I know there can be huge differences between the rule book and what is allowed by tech officials. Oh yeah, I'll be using 4130, or 1020dom. Thanks.

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Boost early and Boost often

Ratfink Wrote:
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> I will be adding a cage to my XR soon and want to
> know the common diameter material used and legal
> for events. I have searched around some rule books
> and it looks like I'm supposed to use some
> gigantic 1 3/4 Dia..095 wall tubing. I would
> prefer to use 1 1/2 Dia. if possible. I know there
> can be huge differences between the rule book and
> what is allowed by tech officials. Oh yeah, I'll
> be using 4130, or 1020dom. Thanks.

Be VERY careful.
Printout the cage specs and compare.
Min main hoop diameter should be 1.75"

It appears that Rally America is reading the wording to mean all the FORWARD of the main hoop bars be 1.75" as well.

Paul Westwick sent a note to FIA in his capacity as CARS Head Tech guy and got a clarification that they meant 1.75 for the tubes over the doors and down the A pillars when using the design of two "Main hoops" starting at the floor, going up the B pillar, over the door then down the A pillar and these two North South hoops connected by East /west tubes at the top of the windsceen and accross the car at the B pillar.

Rally America reads things "uniquely" in several other areas too.

You're in SoCal, who knows what events will be sanctioned by what Company, but you better check carefully with local scrutineers.
4130 being chrome moly is prohibited because of "fears" that MiG welding it could lead to localised embrittlement.
Hundreds of thousands of MiG welded motorcycle frames made of CrMo steel without failures means nothing to Rally America.

Again, check carefully with the rules.

Seen all the photos at www.jvab.f4.ca of Works Ford cages?

a smart person would use those as guides.

Need links?

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

John, I think that with the CrMo being fear its because if you weld it wrong, it gets brittle. Or, at least thats what I've gathered about it. But hell, I have no idea. Normal mild steel DOM is good enough for me.

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Welcome to the cult of JVL drink the koolaid or be banned.

Thanks John, That is exactly the kind of info I was looking for. As far as the design, I have seen those picks and intend on copying them quite closely.

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Boost early and Boost often

Hey Daniel,

Here is the scoop:

FIA rules specify 1.75" in the main hoop and 1.5" elsewhere. This is CDS tubing, which is a certain manufacturing process.

NASA RallySport allows you to use the FIA tube sizes manufactured by either the CDS or DOM process.

R-A allows you to use CDS in the FIA sizes. If you get DOM, then R-A requires you to use the larger 1.75' OD tubing for the main hoop, half-lateral bars and the piece over the windshield opening.

DOM is typicaly easier to get in the US, so you should focus your desing aroudn that. CDS can be obtained but it's harder in some parts of the country than in others.

If you are in the SW and are going to be running events mainly there, then you can get a NRS logbook issued and use the FIA sizes with DOM throughout, most event in the SW are NRS sanctioned. R-A has been accepting NRS logbooks at their events and vice versa.

Look for 1020 or 1026 steel in your tubing. Chrome-moly is not allowed by anyone at this time; the joints have to be heat normalized after welding. Proving that the joints have been normalized is problematic in the field.

If you have seen the pix on this forum of the recent cage built by Dave Clark, then you need to go with NRS for the V-bar in the main hoop. R-A only allows the X-brace in the main hoop, as does FIA.

Decide which sanctioning body to get your car logbooked, and get a hold of a regional scrutineer and work with them closely. You do not need to misinterpret things and have to rebuild some significant part of the cage. Adivce hre is mostly good, but you won't be getting approval from this group! Contacts:

http://www.nasarallysport.com/staff.php

and

www.rally-america.com ; the contact there is Mike Hurst.

Regards and welcome to the craziness!
Mark B.
NASA Rally Sport Scrutineer

Main hoop, front windshield legs, connection between them at the top of the windscreen, and one door bar are required to be in 1.75X.095

All the rest can be 1.5X.095

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Grant Hughes

Not sure where you are getting this one-size-fits-all execpt that is the case for DOM tubing for R-A in the parts of the cage that you list.

Per FIA section 8.3.3 in the Appendix J, article 253 (their specs for non-homologated, shop built rally cages):
- Main roll bar or lateral roll bars according to construction (i.e., the actual deaign configuration of the main cage elements): 1.75x.095 or 2.0x.080
- Lateral half roll bar and other parts of the safety cage: 1.50x.095 or 1.60x.083

NASA is clarifying theie rules wording to these FIA sizes for CDS and DOM; the prior NASA wording in this area is somewhat confusing. R-A allows these FIA sizes for CDS tubing as I understand it. I don't have the CARS specs handy.

Regards,
Mark B.

Why overcomplicate it?

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Grant Hughes

Just my view: Give folks the data, express one's views, and let them decide.

And if we settle on one set of sizes, why not the FIA sizes as the are?

Regards,
Mark B.

NoCoast Wrote:
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> Why overcomplicate it?
>
> Grant Hughes
> www.nocoastmotorsports.net
> Denver, CO

Since it was posed as a question:
When i was trying to find out if this was yet another bizarre Rally America unique twist, ya know like the gary Busey helmet protector protector debacle, I called a well known cage builder in Sweden since they use FIA rules as their template.

More or less quote: "What in hell are they thinking about? How the hell am i supposed to make 1.75 do the radii I need to make the forward parts fit the A pillar SNUG?
What the hell! Sure 1.75 is stronger than the 40mm stuff we have used since 1991, but fat lotta good the extra strength is going to do if we'rte way back from the pillar because the bending problems---typical goddam goddam bureaucratic idiots!!!
" and so on he went.
That's what prompted me top call Paul Westwick and ask him to contact FIA and get a clarification.

So it is it appears, a RA unique reading.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

And to add to the confusion is where CARS requires 1.75"x.12" for all parts of the cage in the paragraph right after listing the varied FIA spec sizes for DOM and CDS for Group N and all FIA events. So, like it has been said, pick your sanctioning body and work to that rules set.

Regards,
Mark B.

Just an update on the CARS cage rules: refer to this just recently published:

http://www.carsrally.ca/CARSRally/Po...E_Nov_2007.doc

CARS appears to be aligning with R-A on the tubing sizes for DOM starting in 2008 (the description referes to consultation between the 2), and moving to allow shop-built cages to be only per FIA 253, App J rules. For DOM, the majority in NA is now aligned along the requirement for 1.75x.095 DOM for the main tubes of the cage. If CDS is used, then the FIA sizes are currently accepted by all sanctioning bodies.

Regards,
Mark B.

Except NASA, which if your under 2650lb (i think thats the number, its up there) you can use 1.5x.120 for the main cage, with 1.5x.095 for the remaining parts. 1.5x.120 is lighter then the 1.75x.095, incase anyone is curious.

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Welcome to the cult of JVL drink the koolaid or be banned.

Dazed_Driver Wrote:
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> Except NASA, which if your under 2650lb (i think
> thats the number, its up there) you can use
> 1.5x.120 for the main cage, with 1.5x.095 for the
> remaining parts. 1.5x.120 is lighter then the
> 1.75x.095, incase anyone is curious.
>
> Feisty Peacock?

Not lighter by enough to make it a prime motivation to change to the smaller bar alone. The smaller tube option was included to allow for better/tighter fitting of tubes in small cockpit cars.

The 1.75x.095 is stronger by about 15-20% than 1.5x.12 for general bending loads; the diffence in strength for point impacts is lot more difficult to calculate. I would recommend the 1.75x.095 option myself, the main hoop is the 'heart' of the cage, and making it strong is important to me.

Regards,
Mark B.

Actually 1.5" x .120" tubing is 1.769 lbs per foot, while 1.75" x .095" tubing is 1.679 lbs per foot. In this case I'd rather use the larger OD tubing which is not only lighter but stiffer too.

Bob

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Opel is a 4-letter word...
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