Rule clarification about Miatas

Discussion related to classification of cars in the NEHA series.

Rule clarification about Miatas

Postby Chief Geek » Sun Oct 07, 2012 1:45 pm

I have a question.

Technical and Safety Requirement 4.E.1 says "Roll bar required in all cars without a full steel roof. Roll bar should be
equivalent in construction to cage specs"

and

Technical and Safety Requirement 4.E.4 says "All Roll cages must have horizontal and vertical bars above, ahead,
behind, and to the sides of the plane of the drivers’ helmet..."

So my question is: Is a Miata with a behind the seat roll bar that runs behind both seats and is braced to the rear package shelf only compliant?

The root of the question is that in my reading of the rules above says that it is not (no bars ahead or to the sides of the drivers head), however, I've seen Miatas compete in this configuration, with and without a hard-top at several events. Can someone clear this up for me?

Paul
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Re: Rule clarification about Miatas

Postby Challenger392 » Sun Oct 07, 2012 6:40 pm

I'm no tech inspection expert, but in reading the rules I would say that a miata with a roll bar would be in compliance of the rules stated. largly due to the fact that rule 4.E.1 requires a car without a steel roof to have a roll BAR not a roll CAGE, it only requires the bar to be equivalent in construction (tubing size, thickness, weld quality, etc) not cage design (bar placement). Although obviously nothing should be run that's unsafe and I encourage a full cage for any car.
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Re: Rule clarification about Miatas

Postby walterclark » Sun Oct 07, 2012 10:14 pm

A suitable rollbar can be used instead of having a secured hardtop. You will have to use arm restraints in lieu of a top and side windows and the rollbar does not exempt the car from the breakout rule.
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Re: Rule clarification about Miatas

Postby PRODOG » Mon Oct 08, 2012 2:10 pm

If I recall the conversation when the rule was written we were trying to eliminate open wheel cars and/or cars without windscreens with just a rear hoop and encourage some kind of front down tubes do tree limbs, etc would have a ramp or other material to deflect before hitting the drivers head/face. That is why the wording is the way it is. I agree it is a little confusing and given the huge interest in Miatas as race cars I think a clearer description is in order for this years rules meeting.

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Re: Rule clarification about Miatas

Postby Chief Geek » Tue Oct 09, 2012 5:47 pm

Ah. The part I wasn't understanding was that reference to cages in the roll bar spec, wasn't about geometry (above, behind, either side), just materials, construction, mounting, etc.

Applying the break-out rule to roll hoop only cars is logical.

I realize the root of the rule about non-metal roofs was written with formula cars in mind and the risk separating the CPU from the rest of the drivers hardware. The windshield frame and the raked, safety glass windshield of a modern-ish convertible should provide basic protection below break-out speeds. I've seen Miata's upside down, happily resting on their windshield frames and trunk lids so I have to believe the designers have thought of this risk.

<begin sarcastic tone>

What about those old British things that claim that the Miata copied them? (Copy??? I don't think so because "fun to fix" is somewhat different than "fun to drive" and doing both at the same time is quite difficult.)

From what I can tell, those old machines that are made of iron-oxide tend to have windshields that are quite vertical and windshield frames incapable of resisting the impact of a big moth much less a tree branch.

<end sarcasm> ;)

Is this a hole or inconsistency in the rules that's worth fixing? Just a thought. I'll leave it to the wise among us to decide. After we give up looking for any of those, we're left with the rules committee.

Paul
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Re: Rule clarification about Miatas

Postby sachilles » Wed Oct 10, 2012 10:31 am

To clarify.
If the miata has an adequate rollbar, and only the factory soft top and normal door windows, are arm restraints required?
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Re: Rule clarification about Miatas

Postby walterclark » Thu Oct 11, 2012 4:27 pm

sachilles wrote:To clarify.
If the miata has an adequate rollbar, and only the factory soft top and normal door windows, are arm restraints required?


I might be wrong on this one but I would say no. That is because in a rollover at one of our hills I cant imagine the odds favor a rag top staying intact and that would be necessary to keep your arms in the vehicle without the restraints.
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Re: Rule clarification about Miatas

Postby KevinGale » Thu Oct 11, 2012 5:20 pm

walterclark wrote:
sachilles wrote:To clarify.
If the miata has an adequate rollbar, and only the factory soft top and normal door windows, are arm restraints required?


I might be wrong on this one but I would say no. That is because in a rollover at one of our hills I cant imagine the odds favor a rag top staying intact and that would be necessary to keep your arms in the vehicle without the restraints.


I can see that but with any other car we are relying on the windows staying intact to keep arms in. The odds of the side window breaking in a rollover is pretty high. One hit against anything and those things shatter into a million pieces. In either case we are basically saying it will probably keep your arms in once. If you roll multiple times I wouldn't count on either of them. So I guess my vote would be the soft top is OK by our rules with a roll bar and subject to the breakout rule.
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Re: Rule clarification about Miatas

Postby honda#72 » Wed Oct 24, 2012 3:34 pm

I ran the S2k for a season with no cage. Factory rollbars, and arm restraits, with the soft top. Walter makes a good point about the fabric coming apart and not keeping your arms in. Kevin also has a good point about any cars' window breaking and not keeping arms in. Maybe with the exception of lexan windowed cars, all cars should have them, wouldn't hurt my feelings. I will likely keep wearing them once I have a hardtop. Jimi wears his all the time, think he told me he started doing so after rolling at Philo.
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Re: Rule clarification about Miatas

Postby walterclark » Thu Oct 25, 2012 6:48 am

walterclark wrote:
sachilles wrote:To clarify.
If the miata has an adequate rollbar, and only the factory soft top and normal door windows, are arm restraints required?


I might be wrong on this one but I would say no. That is because in a rollover at one of our hills I cant imagine the odds favor a rag top staying intact and that would be necessary to keep your arms in the vehicle without the restraints.


I reread this just now and somehow my reply is backwards from what I meant. I think arm restraints are required, for the reason I stated.

And I do agree that tempered glass side windows are only a temporary restraint in the event of a rollover. Odds are good at least one will be shattered. This is why, when I ran glass in the GTI I laminated a clear safety film on the insides of the side and rear windows - well that and to keep small shards of glass from getting in our eyes and all over the place. The stuff I used was intended for commercial building glass application and not only did it prevent the glass from disintegrating all over the place it also made penetration quite difficult - similar to a laminated windshield.
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