Roll Hoop Question

[anthony1k]

The GCR states that there should be a diagonal bar inside the rear roll hoop

“Main roll hoop (behind the driver) shall extend the full width
of the driver/passenger compartment and shall be as near the
roof as possible. It shall incorporate a diagonal lateral brace
to prevent lateral distortion of the hoop (See Figure 8). Any
number of additional reinforcing bars are permitted within the
structure of the cage.”

My question is, does the diagonal bar have to span the entire width of the roll hoop?
Looking at it from the front, is what shown below legal?

[attachmentid=1042]

Thanks

[JoshS]

There is new wording for '08 in the July Fastrack. It's not yet ratified but it probably will be.

"Main hoops must incorporate either a single-diagonal brace, or a double-diagonal “X” brace in the plane
of the main hoop. The brace must be attached at both ends to the main hoop, span at least 50 percent of the
width of the main hoop, and at least 75 percent of the height of the main hoop as shown in figure TBD."

[anthony1k]

There is new wording for '08 in the July Fastrack. It's not yet ratified but it probably will be.

"Main hoops must incorporate either a single-diagonal brace, or a double-diagonal “X” brace in the plane
of the main hoop. The brace must be attached at both ends to the main hoop, span at least 50 percent of the
width of the main hoop, and at least 75 percent of the height of the main hoop as shown in figure TBD."[/b]
So based on the "new wording" my diagonal brace is legal. Correct?

[JoshS]

So based on the "new wording" my diagonal brace is legal. Correct?
[/b]
Yes.

And just FYI, the August Fastrack is out now, and it modifies the wording I quoted above. The new, new wording says: "Main hoops shall incorporate a diagonal brace. The brace shall either be in the plane of the main hoop, or extend from the top of one rear brace (described in 9.4.B.2.c) to the bottom of the opposite rear brace. Automobiles with mid mounted engines can have the lower mounting point attach to the frame of the automobile within six inches of the main hoop. In the case of braces in the plane of the main hoop, the brace must span at least 50% of the width of the main hoop, and at least 75% of the height of the main hoop."

But I think your proposal would still be okay.

[anthony1k]

Thanks Josh!

[dickita15]

as a tech inspector I was told the diagnal must cover at least 50% of the width and 75% of the height.

[ddewhurst]

***The brace shall either be in the plane of the main hoop, or extend from the top of one rear brace (described in 9.4.B.2.c) to the bottom of the opposite rear brace.***

The sole purpose of what was in the past a diagonal connected at BOTH ends to the main hoop has now been degraded to something LESS than it's original purpose. The original purpose of the main hoop diagonal was to add maximum strength to the main hoop for driver protection. The diagonal was to be attached to the main hoop upper corner drivers side with the other end attached to the main hoop lower corner/floor plate passenger side. Will someone please tell/show me how a diagonal attached one end to the top of one rear brace to the bottom of the opposite rear brace provides equal strength as will the diagonal with both ends intergrated within the main hoop per my example above. To take this rule to the worst implementation a person could attach the diagonal to the passengers upper rear brace & to the drivers lower rear brace. That last example my friends shows just how much the rules writters don't have a clue. With the last example the diagonal HAS NOT ADDED ANY STRENGTH to the drivers upper corner of the main hoop.

DUMB, DA DUMB DUMB..............

[Speed Raycer]

WTF???? Jebus H Cryst

They need to mandate a friggin dash bar... not be talking away the manditory hoop diagonal. Guess I'll be writing a letter.

[dickita15]

David and Scott, you guys are absolutely right, this IMHO is not an increase in safety. In trying to figure out why I am guessing that it is because of prod. A lot of classic prod cars are so small that the seat is way back under the main hoop making it hard to do a diagonal like we are used to. This rule rewrite attempts to make the cage rules more the same in the different categories.
At least that is my guess.

[ddewhurst]

Dick, I hear what your saying except that that's pure BS, production guys do that to get their weight rearward. You folks have a British car out there where the driver is approx 6'-3" tall & he sits UNDER the main hoop. We have a driver of same height with same car in the CenDiv that has the legal diagonal tube with BOTH tube ends attached to the main hoop. This CRAP that you state is 100% illegal having the seat/driver under the main hoop. Please read rule GCR-88, 9.4.1.B. & then tell me the seat/driver under the main hoop is legal. This WHOLE main hoop diagonal is CREEP made legal because those doing safety checks each year either dont know the rules or they don't have the sack to do a correct safety check to the WRITTEN rules. All said with a :D because I really don't give a crap what the clueless do or don't do with the rules. I have written roll cage letters over my 10 year involvement with the SCCA including having phone conversations with the past Comp Board Chair from your division. It is quite amazing how people who have a station within the SCCA come of that others who have no station within the SCCA don't know $hit.

I have had conversations with a couple from out your way about ILLEGAL roll cages in ITA/Spec Miatas to which they just want to kind of stuff their toe in the sand & not continue the conversation. :o It's no big deal to ride the middle of the wire & that's why the rules continue to CREEP.

WE see it all the time on this site. When they get backed to the wall on this site they turn on their selective response mode. ;)

[dickita15]

David, I agree with much of what you say. My view of the Prod rules in general and their cage rules specificly is they make little sense and that has, more than anything, caused me not to aspire to race prod. My view has always been I do not care that the prod rules are bad as long as that does not spill over to the classes I care about. I suppose with this change that is what is happening. I now have to decide how much I care that this will allow a less effective diagonal in IT.

And I do not believe I have ever done an annual on HF’s car. He starts his season in Florida

I assume you Miata reference is to the “optional anti intrusion bars” and where they attach. If so there was a lot of action last year. The DD cages had to cut the bar or not race and there were a couple of protests that prevailed against another builder’s cages for where they were attached. I think that is cleaned up now.