Changes in the Door Bar Rules??

Originally posted by charrbq@Oct 6 2005, 03:43 PM
Two cents.  I'm not a welder, nor do I play one on TV, but I've seen the need to use one in the past.

My guy tells me that it's much harder to make an "X" and gusset it properly than to weld two bars parallel to the front and main hoops.  Plus, the bars are continuous, not cut and rewelded.  As an aside, he offered to modify my cage in such a manor and add small bars between the main door bars to add support.  His and my theory is that in a side impact event, with the "X" bar configuration, it would be a lot easier for the intrusion of cars and car parts into the cockpit than with the parallel bars.

I guess you could look at shark cages as an example.  They put parallel bars in those to keep the bad things out.
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They use parallel bars because the spacing between the bars must be small.

A properly designed and executed cage with an X will tie to the dash crossbar and main hoop horizontal crossbar. This will be significantly stronger than two parallel bars welded to verticle tubes without other support.
 
FWIW, the first conversation about the X-only rear main hoop brace design - where the rules also call for "two bars" - was with an SCCA tech inspector, who I actually don't think of as outside of the mainstream.

I didn't say that it necessarily made simple sense, I just call 'em as a I see 'em. Sometimes I'm way off base but regardless of what we think common sense might prevail, we're playing it safe.

It took a week or so for the 1.5x.065" DOM tube for our secondary cage elements to come in but Competition Cages will get to bendin' this weekend.

K
 
Originally posted by Geo@Oct 6 2005, 09:15 PM
God, this sort of stupid stuff is the resaon I've not been around for a while.  While I am not a tech inspector, I'm confident they won't be so goofy about this.  An X is two tubes.

There are many times I think this site does more harm than good.
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You can say it is all you want George, but that doesn't make it the case. And you know what happens when someone writes a protest? They go by what it says in the book, not what somebody feels (at least, that's the way it's supposed to work).
 
The big question (for those of us that have door bars in an "X") is the X design legal (although one bar is cut and re-welded). Is my design going to be ok or am I going to have to put door bars into my budget for next year........
 
***God, this sort of stupid stuff is the resaon I've not been around for a while. While I am not a tech inspector, I'm confident they won't be so goofy about this. An X is two tubes.***

As you said George, you are not a tech inspector. The rules don't say anything about the reader confidence factor & some tech inspectors will read the rule the same as some of us read the rule. Many of us who are being GOOFY understand the meaning of the words one, two & three.
 
geo
I feel your pain. many of my IT friends get frustrated reading threads like this. I am a tech inspector and as I said ealier i would accept the x as two bars so anyone who want to tow up here I will issue a log book, but I can see some inspectors questioning this. Those type of decisions are what made me become a tech inspector. I find value in this type of thread as it helps me refine my argument and makes me more effective in defending truth justice and the american way. :D

besides we are still a lot less silly the the production board.
 
Originally posted by dickita15@Oct 7 2005, 07:44 AM
Those type of decisions are what made me become a tech inspector.
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Ditto. I'll sign off a logbook that has this arrangement, and if you get protested/bumped by Tech for it, I'll help you write the appeal. - GA
 
WOW! How cool is that! Open, forthright, and loaded with moxie! Two tech inspectors with integrity.

The one or two question is interesting. If you were a tiny being that could pass through the molecules of steel, and you were in the main bar of the X, traveling from one end to the other, you would have an uninterupted trip, right? Nothing but steel molecules.
Now if you were in the interupted bar, along the outside edge, traveling along it's length, you would enjoy the same uninterupted trip, right?

but if you were traveling along the top or the bottom, again, in the metal, you would be greeted with an air space at the junction, correct?

So, my answer is that they are actually 1.5 (or so bars), as the second bar isn't truly continuous.

But does it really matter?
 
Originally posted by lateapex911@Oct 7 2005, 05:05 PM
So, my answer is that they are actually 1.5 (or so bars), as the second bar isn't truly continuous.
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i may be mistaken jake but i do not remember anything in the new rules about the two tubes being continuous

see geo what we have to put up with :lol:
 
"Item 5. Effective 1/1/07 and permissible 10/1/06: Allow NASCAR-Style side bars on the passenger side of Showroom Stock, Spec Miata, and Improved Touring competition cars. Change section 18.2.7 to read as follows:

7. Side Protection
Effective 1/1/07 and permissible 10/1/05 >>>>TWO (2) side tubes<<< connecting the front and rear hoops across both door openings are mandatory. Door side tubes may extend into the door... etc. etc..."

TWO side tubes:

One (1) side tube = l

TWO (2) side tubes = l l

Three (3) side tubes = l l l

In common sense understanding of a non strained & or non tortured interperation (rule 1.2.4.) of the rule TWO (2 = l l) is very straight forward & simple to understand.

Will anyone who defines TWO (2 = l l) as being THREE (3 = l l l ) please provide their definition.

Maybe the fact that Production rules have been so far out of control for many years is because some tech inspectors have also been out of control. Did any of you tech inspectors from the North East (or any other Division) inspect Harold's F Production side hoops that DO NOT follow the front pillars, that travel through slots in the hood & terminate at the front spring towers ? That friends is how the Production rules have been CREEPED for many years & now we have some on this site within this thread that are IMHJ willing to creep the Improved Touring RULES. Another Production car from the North East has the main hoop traveling over the drivers head with no main hoop diagonal & the head restraint is 6 inches behind the trailing edge of the main hoop. Yup, it ain't hard to figure out how rules CREEP occures. But then with the new math & all three equals TWO. ;)

Golly, because the rule don't say continious lets make our side hoops, halos & main hoop diagonal out several pieces of tube. :bash_1_:
 
Originally posted by ddewhurst@Oct 8 2005, 11:01 AM
TWO (2) side tubes connecting the front and rear hoops
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I don't know but it is pretty clear to me. Each of the two tubes need to connect one end to the front hoop and the other to the rear hoop. No where in there does it say connect one tube to the front and rear hoop and another tube from the rear hoop to the first door tube and another tube from the front hoop to the first tube.

The second "tube" is no longer one tube, over an inch of it is missing if you were to draw a line from where it meets each hoop. And neither of the two pieces of that tube connect the front hoop to the rear hoop.

I see no reasonable way without an overly burdened interpretation of the rules to conclude a typical X bar alone meets the requirement. IMO to conclude the tubes that intersect the actual complete tube connect the front to the rear is a real stretch and NOT in the spirit of the rule at all.
 
Originally posted by ddewhurst@Oct 8 2005, 11:01 AM
Will anyone who defines TWO (2 = l l) as being THREE (3 = l l l ) please provide their definition.
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Any first-semester welding school student can tell you that any two pieces properly welded together will be considered contiguous and as strong as the original pieces (and, in most cases, stronger). Therefore, any two (or more) tubes welded together can be considered contiguous (unless SCCA has a specific definition otherwise that I'm unaware of. Is there?)

In fact, even though in many cases SCCA *specifically* calls out a continuous tube (such as the main hoop) they tacitly recognize that multiple tubes can be made so by the use of internal tubing and rosette welding.

If you want a definition, dig out the ASTM specs.

The second "tube" is no longer one tube, over an inch of it is missing if you were to draw a line from where it meets each hoop.
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Not true. At worst, taking your logic to the extreme, these tubes will have two small holes in the side. Imagine creating an "X" by bisecting one and welding to a contiguous tube. Then, cut away the originally-contiguous tube. You're left with one tube with two holes. However, you're thinking that the bisected tube is now less strong since it's got "holes". Not true. In a properly-built X bar, all tension and compression forces on the bisected tube are transferred through the "arch" in the the contiguous tube, then back to the other bar, and that arch is supported by the existing tube in the other plane. It's just as strong as a contiguous tube.

Bottom line: "two" tubes welded in an X, with one contiguous and the other bisected and welded to the first, is as strong - I would argue stronger - as two bars welded parallel and/or horizontal between the front and rear. It's certainly better than two bars laid in a different plane and welded in the middle as a psuedo-"X". You may disagree, but I personally have no plans to modify my existing "X" on the passenger and driver's side, except to as an excuse to remove passenger-side glass and mechanisms... - Greg
 
One other thing to consider...straight tubes carry loads, bent tubes are springs: Therefore, the "X" on the passenger side is ultimately stiffer than the NASCAR door bars on the driver's side. The crush space, however is worth it to me. Chuck
 
Therefore, any two (or more) tubes welded together can be considered contiguous (unless SCCA has a specific definition otherwise that I'm unaware of. Is there?)
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[devil's advocate]Well Greg, what you've just argued, is that an X configuration is in fact one tube. B) ;) :023: :happy204: :D [/devil's advocate]
 
(Argh, I'm gonna slap you nex time I see you...) Taking it to the Miller extreme, the entire rollcage is thus one single bar... (your move... :) )
 
Originally posted by GregAmy@Oct 8 2005, 05:31 PM
(Argh, I'm gonna slap you nex time I see you...) Taking it to the Miller extreme, the entire rollcage is thus one single bar... (your move... :) )
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Agreed Greg, that's why I think your original logic is flawed.

Here's another way to look at it. How many tubes are attached to the continuous tube that is between the main hoop and the front hoop/downtube, not including the main hoop and the front hoop/downtube?

As I said, I think it meets the spirit of the rules, but unless a clarification is made to allow it, it's just too easy to argue that there are not two tubes connecting the main hoop to the front hoop/downtube. And the two tubes that make up the non-continuous leg of the X, aren't welded together, they are welded to the continuous tube. So, per Greg's comment, they are not two tubes welded together (and thus not contiguous).
 
Greg, if two pieces welded together is stronger than one piece why SHALL the main hoop be one continious tube ? By your logic we would all have STRONGER/SAFER main hoops if several pieces were welded together to fab our main hoop.

No comment from either of the North East tech inspectors about the two previously mentioned ILLEGAL North East roll cages.

Now for a bit of humor. Greg, how long is a piece of string ?
 
Originally posted by ddewhurst@Oct 9 2005, 07:47 AM
...if two pieces welded together is stronger than one piece...
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I really have no desire to get into a dewhurst BB pissing match, but I do believe I wrote "...as strong as...", not "stronger than". If I wrote otherwise then you can consider this a correction to that effect.

BTW, if you read GCR 18 carefully, there are instances where even the continuous bars need not be so if properly done (support tubing, rossette welds).

Now for a bit of humor. Greg, how long is a piece of string ?
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Depends on how far apart your jackstands are...


To all: As I said, I will sign off a logbook with a properly-done X-bar, but I accept the possibility that SCCA Topeka may disagree. If that happens, a clarification will be issued. However, this is quickly turning into an "angels on the head of a pin" argument, so to completely avoid this argument it's a simple matter of welding a horizontal tube across the bottom of the door to supplement the X. Further, it's going to be very diificult to make effective 'into the door' bars without using multiple tubes (you can see, in fact, that's exactly what we did: http://www.kakashiracing.com/images/rollcage/DCP_4707.JPG). - GA


(On edit: Dewhurst, I see my original reference to "stronger". In context, I mean that, for example, when two plates or tubes are welded together, the actual weld itself is stronger than any particular area of the contiguous plate or tube. I do not mean to imply that the resulting structure is stronger than a contiguous plate because, obviously, it cannot be: any structure is only as strong as its weakest point.)
 
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