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Discussion Starter · #1 ·
I made the mistake of reading the new voted and approved rules in the online Fastrack over Labor Day weekend. Oooh boy.

Specifically the cage rules. There are substantial changes (in at least one case diametrically opposed to the current standards) in the requirements for cage construction.

Am I the only one who understood the proposal for member comment to include a statement that cars with current logbooks would be exempt from these changes? I have searched in the new rules for this statement, and do not find it.

Certainly I am not the only one faced with the prospect of tearing out the current cage and replacing it....at what expense to the bodyshell integrity (especially as our cage is welded in literally dozens of locations to the shell)??? Additionally, no evidence has been presented that requiring this trouble and expense is going to meaningfully improve competitor safety.

Well???
 

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The rule changes regarding the roll cages seem to open up a huge can of worms.

It was mentioned before (on SS or Rally-L, can't remember which) that if existing cars with logbooks were to be "grandfathered" then what is the point of making the rule change. You would have a whole slew of cars that are technically illegal and deemed "unsafe" by the rule book rallying right alongside the newer "safer" cars. What happens if someone gets hurt in an old car, and it is determined that the new cage standards would have protected the occupants? Why were they allowed to run in an "unsafe" car?

I have mixed feelings on this one. As a car owner, I don't want to have to change my cage, it costs money that I could use to buy baby food. But, as I built the cage in the first place, it won't cost me much to change it. Also, everyone should have to follow the current rule book, whether it be class legality issues, or safety issues, no one should get a "leg up". Though, most will argue that following the rule book is a mystic art, best left to those with extra senses and the like. I would hope that there was plenty of thought put into these changes and that they are for the better. If that is the case, then I think the changes should apply to all equally.

And lastly, as I've been told by many a people, I have no idea what I'm talking about. You see, I have only been around these parts for a year, and I'm being learnt by many that "if it ain't the way it we used to do it, then it ain't the way we gonna do it".

just my 2 1/2 cents...
 

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Discussion Starter · #3 ·
For what it's worth, I spoke with my (professional) cage builder this morning....my 1.375/0.95" CrMo alloy tubing is stronger and makes a stronger cage than the 1.500/0.90" tubing that would be allowed under the new rules....so it's not just about safety IMHO.
 

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>http://scca.org/news/fastrack/02-10.pdf
>
>It's October Fastrack. Check pages 7,8.
Honest this question is not an angry complaint, it is in the voice of complete bewilderment and it's dead serious:
Why don't people cut and paste things right to these pages so we can see here and refer to the document HERE?

What is the point about the linkie-thangs which one has to go back and forth to see?

Come on guys put things here.


John Vanlandingam
Seattle, WA. 98168
 

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True, but CrMo tubing is not as resistant to fracture as mild steel tubing.

Also, when alloy tubing is welded it needs to be 'normalized' which involved heating up to (relatively) high temps and cooling slowly to stress relieve the welds.

I doubt if this happens on a regular basis with the existing alloy cages because you would need a pretty large oven and just a bare shell with tubing OR do each individual weld one at a time. Seems pretty unlikely.

Not taking sides, just giving some details from an engineering perspective. Stronger generally means more brittle.

Matt Manspeaker
Seattle, WA USA
89 323GTX - Open
 

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Here you go, John...

5.6 ROLLOVER PROTECTION
A. A roll cage is required for all vehicles entered in SCCA ProRally and SCCA ClubRally competition, and are recommended for SCCA RallyCross competition.
B. No change
C. Roll cages not constructed to FIA specifications must adhere to the following minimum specifications. Specific installations are subject to approval by the Chief Scrutineer.
1. The primary purpose of the roll cage is to protect the occupants of the vehicle during a rollover or serious accident. This purpose should always be considered during the design and fabrication of the roll cage.
2. Material: All required primary roll cage elements (including diagonals and side bars) must be constructed from seamless, DOM,CRW,WHR,or WCR mild carbon steel. Equivalent materials may be accepted upon the approval of the Chief Scrutineer. All required primary roll cage elements must adhere to Table 1 for diameter and wall thickness (for the purpose of determining tubing sizes, the vehicle weight is determined full of fuel and spares and race ready but without occupants).
3. Mounting: Roll cage terminal ends must be attached to the frame or body structure in locations that will support maximum impact loads and will not shear either in compression or tension (push through or pull from the structure). Mounting plates shall be welded to the frame or body structure, and must have a minimal area of 10 times the diameter of the tubing being attached (i.e. a 1.5" diameter tube would require a minimal mounting plate area of 15 square inches). The mounting plate must also be at least 2 times the diameter of the tubing being attached in any dimension. (i.e. a 1.5 diameter tube would require a plate at least 3.0" wide in any direction. a. Welded plates: Mounting plates must be at least 1/8" thick and must be attached such that the welding does not weaken that area of the vehicle structure. Roll cage mounting plates shall extend onto vertical structures of the vehicle (such as door sills or tall frame sections) wherever possible.
4. Welds: All roll cage joining must be performed by GTAW (TIG), GMAW (MIG), FCAW (flux cored arc), or SMAW (stick arc) welding. Oxy-acetylene welding and brazing are not acceptable. All welds must be of high quality with good penetration and exhibit no significant undercutting of the parent metal. All welds must also be 100% complete (i.e. must wrap completely around the perimeter of all tubes). Acceptance of any questionable welds is at the discretion of the Chief Scrutineer.
5. Bends: All bends in the roll cage tubing must be smooth and present a minimal amount of tubing distortion. Crushed tubing, such as that which occurs when using pipe benders, is not acceptable.
6. Required roll cage primary elements: All non-homologated roll cages must contain the following components at a minimum.
a. Main Hoop: Must be made from a single bent piece of tubing and be located no more than 10 inches behind the driver or codriver, or more than 5 inches in front of the back surface of the most rear-mounted seat. The Main Hoop must extend the full width of the driver/co-driver compartment, and must lie in a plane less than 20 degree from vertical. The top surface must also be at least 2 inches above the helmet of the driver when in normal seated position. The Main Hoop is required in all roll age configurations.
b. Front Hoop: Similar to the Main Hoop, but located around the front windshield. This Hoop must fit reasonably tight to the body structure in order to minimize obstruction of the view through the windshield.
c. Roof Bars: Two Bars must join the Main and Front Hoops. These Bars must be located as close to the sides of the roof structure as possible, and must be at least 2 inches from the driver and co-driver's helmets when in normal seated position.
d. Rear Bars: Two Bars must join the Main Hoop to the rear of the vehicle. These Bars must attach to the Main Hoop as close to the upper bends as possible, but no more than 6 inches below the top surface of the Main Hoop and not closer to each other than where the Roof Bars attach to the Main Hoop. These Bars must be kicked rearward at the bottom at an angle of at least 30 degrees from vertical. These bars must be straight and not contain any bends.
e. Diagonal Lateral Bar: Must run from one upper bend of the Main Hoop to the lower end of the Main Hoop opposite leg (either side upper bend is permissible). Must be attached as close as possible to the upper bend and the lower attachment point as possible. An additional bar shall run from one upper bend of the Main Hoop to the lower end of the opposite Rear Bar.
f. Side Sill Bars: Two Bars must join the Main and Front Hoops. These bars must be located as close to the horizontal as possible, and must be no more that 6 inches above and 4 inches inward from the lower door sills. Additional door bars may be added, but these Side Sill Bars are still required on each side of car.
g. Alternate design - Side Hoops: Instead of using a Front Hoop and Side Bars, these components may be substituted with Side Hoops and a Windshield bar. These Side Hoops must extend from the Main Hoop, one on each side, forward and along the Apillars to the floor. A Windshield Bar then joins these two just above the windshield. All clearance rules still apply.
h. Alternate design - Halo Hoop: Instead of using a Front Hoop and Side Bars, these components may be substituted with a Halo Hoop and Windshield Legs. The Halo Hoop is a single piece of tubing bent to run from the windshield, then back to the Main Hoop on the opposite side. Windshield Legs then connect the Halo Hoop, along the A-pillars, to the floor. All clearance rules still apply.
i. Front Gussets: Must join the Front Hoop and Roof Bars (or Side Hoops and Windshield Bar, or Halo Hoop and Windshield Legs) on both sides of all junctions. These Gussets may be made from tubing at least ¾ inches in diameter and .060 inches thick, and must extend onto each joined tube at least 2 inches but not more than 3 inches. As another option, tubing of the same thickness and diameter as the roll cage tubing may be split and formed into Gussets and must extend onto each joined tube at least 2 inches but not more than 3 inches. Regardless of which type of gussets are used, they must be fully welded all around.
j. Other Designs: Roll cages of other designs may be accepted by the Chief Scrutineer upon presentation of certified data verifying that this design is able to withstand the simultaneous application of the following three loads onto the roof plane of the structure (as if the vehicle were upsidedown and the loads applied by the ground) * 1.5 G lateral load (either direction) * 5.5 G fore/aft load (both directions) * 7.5 G vertical load (compression) G is calculated with the vehicle fully loaded (including occupants)
7. Padding: Any portion of the roll cage which could come in contact with the driver or co-driver's helmet must be covered with energy absorbing material (high density) of a minimum thickness of ½ inch. 8. Inspection: An inspection hole of at least 3/16 inch diameter and at most ¼ inch diameter must be provided in a non-critical, non-curved area of the Main Hoop to facilitate verification of wall thickness. Weight Tubing Size up to
2499 1.500 x .095
2500 to 3499 1.500 x .120 or 1.750 x .095
3500 to 4499 1.750 x .120
 

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So are bolt in cages out entirely?? I already have one installed. Can I use it still or can I have it welded at all the points and then to the floor of the car?? Please send some advice as I am having the car welded for other issues as we speak. I need to get this to the welder so that I won't have to get it done twice.
 

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RE: "can of worms"

Your points make alot of sense. Still, they let us use Snell 95 helmets for some period of time after they are made obsolete by Snell 2000, right? Maybe they could have some sensible overlap allowing grandfathering for some finite period of time, upon which the grandfathering would expire. In a rather unrelated instance, baby seat attachment rules in cars have changed enormously in the past couple of years, yet there is no provision for manditory retrofit of old cars. The safety concern in that instance is just as strong as in our cage instance. I think redesign of all current rally cars is almost as unfeasible as retrofitting all road-going cars for proper baby seat attachments. In many instances (like Phil Smith's) I bet it would be more feasible to find a new shell and move over the transferable race parts than to retrofit the existing car. I wonder how this will shake out...

-Rod Van Koughnet
Tulsa, OK
 

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>>http://scca.org/news/fastrack/02-10.pdf
>>
>>It's October Fastrack. Check pages 7,8.
>Honest this question is not an angry complaint, it is in the
>voice of complete bewilderment and it's dead serious:
>Why don't people cut and paste things right to these pages
>so we can see here and refer to the document HERE?
>
>What is the point about the linkie-thangs which one has to
>go back and forth to see?
>
>Come on guys put things here.
>
>John Vanlandingam
>Seattle, WA. 98168

Dear John,

Many of us prefer the links because (A) it keeps the text volume down here, (B) it allows us to go look it up only when we want to, and (C) that's the way the web has evolved to work. That's why they call it a "web" and not a "big-honkin' central storage depot with everything in it"

Next thing you'll be saying is that you print out all these threads and read the hard copies. :)

As a serious suggestion ... you might consider opening more than one browser window at once. Then you can view Specialstage in one and the SCCA link in another, for example. In a typical session, I might have a dozen different browser windows open. I'll go into the "Read New" screen and open all the items of interest to me. Then I'll go to each window, in turn, and read them. There's no going back and forth. There's only forth.

Ken Hawley
Kalamazoo, MI
Audi 4000Q - #577
 

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You can keep the bolt-in cage. From Doug Robinson the preferred method is to tack weld all the joints, take out the bolts (so they won't be affected by heating), weld all around the joints (not in the bolt holes), and put the bolts back in.
You will have to comply with the appropriate floor mounting - if the pads just bolt to the floor, you'll have to make mounting pads that extend up the rocker boxes. Check the rules posting.

Tom Bier
 

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Discussion Starter · #15 ·
My point is that my current cage is 1.375/0.95" CrMo, built and installed in a bare shell by a knowledgible professional cage builder who is quite familier with working with alloy tubing; for what it cost and the stage at which he had the car, it should be done right.

Cutting this out and installing a 1.5/0.90 tubing cage means either going to mild steel or completely stripping the car and doing it over in 1.5/0.90 CrMo tubing...regardless of what happens in my case in particular, I'd bet beer I know which is more likely to happen in general terms, and I have a hard time believing that the mild steel will be as strong as the original smaller diameter/thicker walled cage. But then, I am not an engineer, so I am willing to be shown that I am wrong. Which is what I want if I am expected to replace the current cage.
 

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It is not just strength. Strength is very important and is easy to calculate, so many people like to talk about it, but you must also consider stiffness. CrMo and mild steel have the same stiffness (for all practical purposes), so you are only looking at a difference in shape. The bending stiffness of a 1.500 x 0.090 tube is 23% higher than the bending stiffness of a 1.375 x 0.095.

Another important consideration is energy absorbtion at ultimate strength, but that usually requires specific testing to show the effects shape of the tube and the weld joints.

Just for comparison purposes, assuming annealed 4340 (just picking a CrMo, there are a lot of them), the 1.375 x 0.95 CrMo is up to three times stronger in tensile strength and is about 2 3/4 times stronger in bending situations, but again, it is only 97% as stiff in tension, and 80% as stiff in bending.

Matthew
 

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As the rules are specifically written it would seem Phil, that you and your builder have the option to submit the engineering proof that your current cage can support:
1.5 G Lateral Load (either direction)
5.5 G Fore/Aft load (both directions)
7.5 G Vertical load (compression)
simultaneously onto the roof plane of the structure (emulating a roll over situation)
the 'G' unit is calculated with the vehicle fully loaded including occupants.

This might be easily done if your cage builder uses a CAD/CAM engineering system. However for me in the Colt which the cage was built by person-X, I haven't the foggiest.

I hope the official SCCA Chief Scrutineer will clarify.

NOTE: old cages were not grandfathered in for needing to add gussets were they?:(

Rob Dupree
 

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RE: "can of worms"

Here is my understanding.

If you have a new Cr-mo cage you need a stamp on it by the
end of the calendar year. This to me implies grandfathering
being allowed. Bolt in cages can be upgraded, and in most
cases can be. I think the total number of cages that will
be made obsolete is rather small. If yours is poorly installed,
the rules may effect you.

paul t-
 
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