Rules change concerning roll cages.

[bmw22]

Just in the past week or so, this appeared.

 

"15.6.7 Diagonal Brace

One (1) diagonal brace shall be used in the same plane as the main hoop. The diagonal

must be one piece.* One end of the diagonal brace shall attach to the corner, or

horizontal part, of the main hoop above the driver’s head, within twelve (12) inches of the

driver’s-side corner. The other end of the diagonal brace shall attach to the mounting

plate (or to the main hoop as close to the mounting plate as practically possible)

diagonally opposed to the driver’s head (passenger floor).

*This is not intended to disallow bolt-in diagonals.

Note- there have been cases where a horizontal bar is installed in the plane of the main

hoop, then the diagonal. This results in the diagonal bar terminating on the horizontal

bar instead of the required termination point. The diagonal should be installed first."

 

This makes no sense. If the intersection is welded correctly, the horizontal and diagonal become one piece and it makes no difference which bar started out as two pieces. There is no structural/load bearing reason for this rule. All this rule does is require some folks to hack up there roll cage. I would argue that cutting out and replacing would result in a weaker cage overall.

 

Why add this rule now, after all the winter car builds are completed? To add a rule like this without an exception for cars already built is bad policy. This rule is just plain bad. If it was truely safety based, then the bolt in diagonal should be banned, because the bolt in could never be a strong as a welded in two piece diagonal.

 

This rule does not make a car safer.

This rule does make it more difficult for cars to come in from other series.

This rule needs to be looked at to see if it makes sense and if it is the best thing for NASA and driver safety. If not, it needs changed.

[King Matt]

This has come up many times in the past. The way the rule was previously written caused some confusion, but the fact is that read properly, it was ALWAYS required for the diagonal to be one piece, because it said one end shall start in the upper corner and the other end shall terminate at the plate in the other corner. There was no correct interpretation of the old language that justified terminating one end of the diagonal on a horizontal bar, but some people who did that argued that it was unclear. I see this merely as a clarification, not a change.

[JimG005]

This reply clearly is not responsive to the points raised by Mark. If criteria for enforcement of a rule change, then that is little different from changing the rule itself. Further, it seems really hard to justify such a change at this point in the season. Just creates a hardship for racers that is entirely avoidable, even IF the enforcement chage were to be implemented. Why not provide some grandfather provisions, especially for cars that were inspected and approved previously?

 

The issue of the need for the change (clarification?) is a different one. Is there some reasonable answer to the questions raised by Mark? For one, I hate to see NASA get on the slippery slope of arbitrary (i.e. not supported by evidence) rules and rule enforcement changes. I believe that is one reason why this series is so popular and also why some of the other organizations are having a hard time understanding their losses in numbers.

[King Matt]

It's not a change, it's a clarification. This was the criteria all cars should have been held to all along. The fact that someone may have slipped through tech does not mean NASA should sanction that. I'll give you another example. For years NASA has had a rule requiring 360-degree welded tubes on rollcages. I had a car that got a logbook in another region without having the front downtubes welded 360. When I showed up in my new region for an annual a few years ago, I had to fix it. Having a logbook and prior annuals did not make it OK to not be in compliance with the written rule. This is no different.

[bmw22]

Edited March 26, 2008 by Guest

[bmw22]

Edited March 26, 2008 by Guest

[Keith]

Before I comment on this, I'd be interested in hearing the technical benefits of the stated method of design versus other designs that are likely out there.

[FBody383]

I would argue that cutting out and replacing would result in a weaker cage overall.

 

Using this definition, a properly welded cage is "one piece".

 

Which is it?

 

When I started bulilding my CMC car this year I had questions about this. I agree with Matt that the change is only a clarification. Had wording similar to that of the main hoop been used originally, "One continuous length of roll bar tubing shall be used as the main hoop (diagonal)," there would not be any need for the clarification. Also, I'm not familiar with NASA's standardization of training for tech inspectors.

 

Before I comment on this, I'd be interested in hearing the technical benefits of the stated method of design versus other designs that are likely out there.

 

My BMW mechanic worked with an engineering firm on a cage design for World Challege car that had greater "technical benefits," as demonstrated by FEA analysis, than the standard cage. The sanctioning body would not certify it; even though it "should" have perfomed better.

 

Before you ask, yes I'm a rookie and this is my first racecar. If you want to talk about my experience in interpreting rules and regulations, drop me a PM.

 

David

[bmw22]

Edited March 26, 2008 by Guest

[King Matt]

Mark, a diagonal bar that was split at the horizontal WAS NEVER LEGAL even the way the old rule was written. You can argue that the rule should have been different, but this is not a change. Whether it was detectable, or even enforced, or which method is better, are different matters, but the fact is that if the old rule was read properly, the only legal way to build the cage was with a single, uninterupted diagonal brace. There are numerous examples of differences in NASA's regulations compared to other sanctioning bodies, and there are instances where professionally built cars may not be in compliance. This is nothing new in racing. The 360-degree rule is comparable, because there are other sanctioning bodies that accept 270 degrees as sufficient, but that does not make it NASA-legal.

[bmw22]

Edited March 26, 2008 by Guest

[King Matt]

Here's a quiz: how many ends does one piece of tubing have?

 

If one end shall attach at the top corner of the main hoop, and the other end shall attach at or near the plate at the other end, how do you interprete it as being legal to terminate two additional ends of that same tube on a horizontal bar, regardless of how seamlessly they are welded?

[Keith]

My BMW mechanic worked with an engineering firm on a cage design for World Challege car that had greater "technical benefits," as demonstrated by FEA analysis, than the standard cage. The sanctioning body would not certify it; even though it "should" have perfomed better.

 

Before you ask, yes I'm a rookie and this is my first racecar. If you want to talk about my experience in interpreting rules and regulations, drop me a PM.

 

David

 

Been there, done that. My CMC cage was originally designed and installed by a Grand Am shop. They added some pieces (and weight, mind you) to protect the fuel tank. I was forced to change this design at no small cost to follow the rules. Needless to say I was not amused and now my gas tank is much more exposed to rear and side impact. But it's legal now...

 

I guess I post this as a cautionary tale.

[bmw22]

Edited March 26, 2008 by Guest

[bmw22]

Edited March 26, 2008 by Guest

[Driver]

As a former professional welder, I would like to reitterate this:

If the diagonal goes from upper left of the main hoop to the lower right of the hoop it makes no difference if it starts out as one piece or two pieces. If welded correctly, it is one piece! And it is certainly stronger than any bolt in diagonal.

 

I would also add that cutting and rewelding DOES weakend the cage while also making it technically one peice.

An old and very common saying about welds is; "The weld is stronger than the steel around it!" This is true, due in no small part to the effect of welding on the steel. The steel around the weld is made slightly more brittle by the heat. This isn't a big deal at all if you weld it right the first time, but each subsequent re-welding of the seam exaserbates this condition, and will lead to a weaker overall structure.

 

In summation:

In the intrests of safety, a 2-peice diagonal should be allowed, provided the welds are 360deg.

Hell, require TIG on 2-peice bars if you have to, just don't make everyone go hacking up more than they have to.

 

People come to NASA because it's more "By racers, for racers". Laying out rules like this (at a time like this) is not in keeping with the ideals that brought 80% of us here. Granted, when dealing with insurance companies, it can't always be a democracy. If that's the case, just tell us that Daddy Insurance is making you do it.

[bmw22]

Edited March 26, 2008 by Guest

[LMan]

Leaving the metallurgical aspects aside, Matt is right in that this closes a loophole that has been used for a long time...not a brand-new rule. You can argue that its not a good rule (and are), but its been the rule for a while...just not written clearly enough in the past to prevent folks from making 2-piece diagonals and getting through tech.

 

I wish you luck in your attempts to have it changed.

[FBody383]

The first statement you took out of context. i was referring to the additional heat cycles required to remove and re-weld. At no point do my statements contradict themselves.

Fair enough; I stand corrected, please accept my apology.

 

Taken in its entirety, my reading of section 15.6 indicates a single diagonal brace in the main hoop. At this time, I believe the harness bar isn't considered in the cage until 15.6.17 and then as an allowance for safety, both in terms of belt mounting and lateral impact. I also scanned those other guys' rules and read it as a continuous, 1 piece diagonal.

 

I had opportunity to speak to a class director today and asked about this rule. I asked him to clarify to his folks how this would be handled for cars with current logbooks versus new cars whether orginally a NASA car or not.

 

I wish you luck in your attempts to have it changed.

Or at least the implications to existing cars clarified. I am coming to the opinion that existing cars should be grandfathered unless and until ANY changes are made to the cage.

 

I decided to come race with NASA, in part, because this kind of idea exchange happens and appreciate that you are questioning this for your group.

[bmw22]

Edited March 26, 2008 by Guest

[Keith]

I would support a grandfather clause for cars with current logbooks.

[bmw22]

Edited March 26, 2008 by Guest

[Keith]

Fair point. I guess my view (and not necessarily the correct one, I know) is that if a tech official actually looked at the car in the past and said it was "OK to Race" then I think it is sensible to grandfather the car in. A static piece of paper is one thing and a look-see by an official is another.

 

As far as a car that was built in the offseason and has never been teched ever? That's a tough one but, boy, this clarification sure came late in the game for that guy...

[King Matt]

I wouldn't be surprised to see a clarification of this that grandfathers existing cars with current logbooks, because in previous discussions on this topic, that came up as the direction that would be taken. But I wouldn't hold your breath hoping that new cars will be accepted with this type of bar. Whether a regional tech director said it was OK is irrelevant. There are numerous things that have passed in one regional and failed in another. No regional tech director has veto power over the CCRs.

 

Mark, you keep using the door bar rule as justification for your interpretation of one or two pieces. The door bar rule requires "at least two door bars" on each side, but it has no language whatsoever directing the placement or location of the ends of those bars. So if you want to argue that an intersected X should be construed as 3 bars, that is perfectly legal since the rule requires "at least two."

[bmw22]

Edited March 26, 2008 by Guest