Newbie- HPDE1- Miata roll cage question...

[crxjuice]

Hello all! I am obviously a newbie to this.. I will be attending the HPDE1 on April 9th. My question is for a miata do you need a weld in roll cage or can you use the basic roll bars like the ones on the pic... I know that the mulitpoint cages are much better but for the sake of using the car for HPDE1 next weekeed will it fullfil the requirement?

 

 

[whoahstu]

That's known as a "style bar" as it offers no protection in a rollover and is thus, not allowed. Some even refer to it as a "mousetrap" as the bar can easily fold forward and flat, further injuring the driver. You will not pass a NASA HPDE tech inspection with that bar. The car will not be allowed on the track.

[kbrew8991]

You'll need a beefier option than that unfortunately - something that goes all the way across horizontally above driver's head level, at least 1 diagonal brace, and at least two rearward braces. Not a full cage, but definitely more protection than the basic style type bars offer.

[crxjuice]

thanks! I appreciate your advice.. I think Ill leave the Miata at home this weekend.

[TurboShortBus]

11.4.7 Roll Bars

All open cars should have a roll bar installed to help protect the occupant(s) from injury

during a roll-over. The roll bar should be able to withstand the compressional forces

involved in supporting the full weight of the car. The roll bar’s main hoop should extend

the full width of the car (except certain cars that have been approved by NASA). The

main hoop shall be one continuous piece with smooth bends and no evidence of

crimping or wall failure shall be present (i.e. should be Mandrel bends). All welds should

be of the highest possible quality, with full penetration [Ref:(15.6.15)]. All cars with roll

bars are required to have adequate roll bar padding per CCR section #15.6.4. In cases

where the driver’s head may come in contact with the roll bar should the seatback fail, a

seatback brace is required in conformance with section #15.6.22. The material and

minimums are as follows: (All cars with full roll cages should conform to the applicable

sections found in section #15.0.)

 

Vehicle weight DOM or ERW

Under 2000 lbs. 1.50" x .120”

2001 - 3500 lbs. 1.75" x .120"

Over 3500 lbs. 2.00" x .120"

 

Vehicle weight Alloy (CM)

Under 1500 lbs. 1.375" x .095”

1501 - 2500 lbs. 1.625" x .095"

Over 2500 lbs. 2.000" x .095"

 

This portion of the HPDE section of the CCR only mentions a roll bar having a main hoop; the use of a diagonal bar and rear braces, along with chassis mounting plates, is not mentioned. Don't get me wrong; I'm not saying that more bars would not be a better idea, as you cannot have "too much" safety. I'm just saying that, per the letter of the law, the other items are not mentioned, and the "style bar" could be permitted in HPDE.

 

This may vary on a regional basis, so it might be best to check with the head of your region. Some regions allow convertibles with "factory rollover protection" to participate in HPDE, and in my opinion, some forms of FRP are not very good. For example, Honda S2000s have small roll hoops behind the seats that are typically below the level of the driver's head, even before a helmet is worn (unless the driver is only about 5 feet tall), but they are considered to be acceptable in some regions. There are also some Mercedes convertibles that have a retracted roll bar that pops up in certain situations (if the car is starting to roll over, etc.), and I really hope that system works when the time comes, and there's only one way to find out. Neither of these forms of FRP have diagonal bars, rear braces, etc.

 

Now, if you're going to go through the time, effort, and cost of installing rollover protection in a vehicle that does not have any (Miata, Mustang, etc.), then you shouldn't waste any time on a "style bar," as there are many companies that make a more proper 4-point roll bar that will serve the purpose much better (although no safety gear is foolproof) and probably cost the same or even less.

 

Mark

[dpspeed]

Crxjuice,

 

Congats on bujying a Miata - it is a great track car that will teach you a LOT. I've had two of them.

 

Is the car daily driven or will it be driven on the street?

 

If the answer to this question is yes, then buy a 4 point roll bar. If the answer is no, then I would seriously consider a 6 point cage.

 

I've had both and I can tell you that the 6 point cage isn't for the street. It is a pain to get in and out of, the bar in the footwell is annoying on trips over 30 minutes and there is a lot more steel near your head.

 

If you are new to the Miata community, you'll find this company sooner or later . They've been building Miata roll bars for like 15 years...

 

www.bethania-garage.com

 

For the track, you will probably want the Hard Core. If you have a glass rear window or aftermarket top, just call Tom @ Bethania-Garage to make sure everything will fit.

 

My 90 Miata had upgraded brake pads, Falken Azenis tires, a cage and race seats - it is the most fun track car I've had (not the fastest though...).

[whoahstu]

I'm just saying that, per the letter of the law, the other items are not mentioned, and the "style bar" could be permitted in HPDE.

 

I understand the argument, but in this instance the bar would fail per the second line of the rollbar section of the CCR.

 

11.4.7 Roll Bars

The roll bar should be able to withstand the compressional forces

involved in supporting the full weight of the car.

 

We seem to be confusing factory roll hoops, designed to provide protection in the event of a rollover, with the Miata "style bar" that is intended to be flashy and chrome. The units I've seen installed can be bent fore and aft by standing in the cockpit while pushing and pulling on the two hoops.

 

 

[TurboShortBus]

We seem to be confusing factory roll hoops, designed to provide protection in the event of a rollover, with the Miata "style bar" that is intended to be flashy and chrome. The units I've seen installed can be bent fore and aft by standing in the cockpit while pushing and pulling on the two hoops.

 

 

The first photo at the top of this thread does not show how the bar is mounted, while this second photo shows that the mounting is inadequate (it is more helpful than the first photo). So yes, based on the second photo, the chrome "style bar" would fail HPDE tech inspection.

 

FWIW, I was driving next to an S2000 over the weekend, and the average-looking driver was sitting with his head several inches above the stock rollover protection. IMO, this is borderline worthless, as the head is still free to contact the ground in a rollover before the structure does.

 

Mark