NASA specific roll cage question in Honda Challenge

[71dsp]

I am in the middle of having a cage installed in an H2 Honda Prelude. I saw this cage design (I hope the page owner does not mind me hotlinking):

 

 

I'd like to run the additional tubes from the rear mounting points to the lower mounting points of the main hoop. My question is, does this tubing have to meet the minimum required wall thickness for the cage?

 

In the NASA CCR, regarding additional roll cage tubing, the CCR says:

 

Section 15.6.17 Additional Reinforcement

Any number of additional reinforcing bars are permitted within the structure of the cage provided that they are installed strictly for safety and do not violate CCR Section #15.6.2 Intent. This rule does not permit reinforcements in classes with spec cages. All required bars must be made of the same material and meet with at least the minimum specifications for size and thickness.

 

For my application, I must use 1.5x0.120 mild steel tubing. My question is, for the additional bars, can I use 1.5x0.095? It's not a lot of weight savings, but everything helps. The CCR says "All required bars must be made of the same material and meet with at least the minimum specifications for size and thickness." My interpretation is the rule is saying that "required tubing" means the tubing that is required by the CCR in the cage design, and thus the additional tubing can be of a different spec. Maybe my interpretation is incorrect?

 

I asked over at Honda-Tech, and I received some mixed answers, so I thought I'd ask the source for clarification.

 

I know that for SCCA all of the bars in the cage must meet the minimum required tubing specifications, but I'm wondering about the interpretation of the NASA rule in the CCR.

 

Thanks for your help!

[BrianZ]

Section 15.6.17 Additional Reinforcement

Any number of additional reinforcing bars are permitted within the structure of the cage provided that they are installed strictly for safety and do not violate CCR Section #15.6.2 Intent. This rule does not permit reinforcements in classes with spec cages. All required bars must be made of the same material and meet with at least the minimum specifications for size and thickness.

 

All Bars must be of minimum thinkness! so if you are required to put 1.5 x .120 that is what you have to use for all the bars.. Safty is on place you dont want to skimp. Trust me on that one..

[71dsp]

All Bars must be of minimum thinkness! so if you are required to put 1.5 x .120 that is what you have to use for all the bars.. Safty is on place you dont want to skimp. Trust me on that one..

 

All required bars must be made of the same material and meet with at least the minimum specifications for size and thickness.

 

Notice that it says required bars. I'm not talking about using thinner walled tubing on the required bars, just a couple of optional bars.

 

As for safety, I'm hardly skimping. The cage will be built to much more than the minimum required by NASA.

 

I'm just curious because the bars are optional, so either they're there, or they're not. The reg mentions that all required bars must be of minimum thickness and diameter, which appears to imply that optional bars can be of a different specification.

 

Don't get me wrong, I'm not trying to install 0.5x0.010" tubing that will fold like a wet noodle. I just want something for some chassis reinforcement that won't be as heavy as 1.5x1.20"

[vapor]

you're not saving a significant amount of weight by using .095 wall tubing when compared to .120 wall. Unless you have a bunch of .095 laying around and want to use, there is no point to run that tubing if your weight requires .120

[Ryan F.]

Non "required" bars may be different size.

[turboice]

Just playing devil's advocate for you to consider potential risks of your decision.

I just want something for some chassis reinforcement that won't be as heavy as 1.5x1.20"

That is a really dangerous thing to put up in writing.

 

I agree as written the rules would not explicitly require optional tubing to be of the minimum specs for your car's weight.

 

However:

15.5.2. Chassis stiffening is a side benefit of a good roll cage system, but it is not the intent of these rules. Parts of the cage deemed by the Chief Scrutineer, to serve no practical purpose other than chassis stiffening may be considered in violation of the intent of these rules (Note: Some class rules allow for chassis stiffening.). The Chief Scrutineer may order the removal of said parts, or require that the vehicle owner redesign, reconstruct, and re-certify the roll cage if warranted. The removal or redesign of the cage, whole or in part, to comply with these rules, does not imply that penalties will not be issued for violating the intent of these rules.

 

There are several positions that could be taken by a competitor in protest:

 

1. You have publically stated that the additional bars are for chasis reinforcement. (I don't know if HC permits stiffening or not.) So I assume by chasis reinforcement you meant to reinforce the ability of the chasis to protect the driver in an incident.

2. Why would any one want an optional tube that is for the purpose of improved safety and not want that tube to be of the same minimum specs? By utilizing a lower spec - an agressive interpretation could be that the tube was added for stiffening and not safety.

 

I know a Prelude is one of those that it is hard to get down in weight - but for the 4 lbs saved on those two optional bars is it really worth the risk of protest or a future change in the rules?

 

BTW SCCA GCR language is similar regarding all required pieces - the IT rules for some reason expands the requirement to all tubing including optional to meet the min specs for weight.

[Crashdevil13]

The cage in the photo would not pass tech as it sits. There is no harness bar in the main hoop. As for the wall thickness of the braces, just use the .120, total weight is not much different (less than 3 lbs per 30 feet!)but BE SURE TO USE DOM TUBING!!!! DOM (Drawn Over Mandrel) tubing is much more consistent in wall thickness than ERW. It does not matter what you ask for when you buy your tubing, it's wall thickness must be MEASURED at .120, not .116. Good Luck, if you have and specific questions please feel free to contact me directly.

[slammed_93_hatch]

The cage in the photo would not pass tech as it sits. There is no harness bar in the main hoop. .

 

thats wrong and its right.

 

that cage is a FIA aproved cage, and that design has been used in FIA competition.

 

the nasa CCR says that if your car is log booked and legal for another sactioning body then it is legal for NASA.

 

there have been 4 cars that run similiar cages in NASA, all of them were raced in FIA goup N, IIRC.

 

Spoon accord, spoon fit, and spoon integra, and i think the DC5 (rsx) spoon integra also runs a simialar cage

[Crashdevil13]

Jimmy,

 

You are indeed correct. As a tech inspector for the local NASA region, I would not let it pass without that current FIA logbook.

 

The time/$/difficulty involved in welding 1 bar into a cage is minimal. I suggest this route as it provides a better mounting point (I have seen the crash test data) and is not illegal for FIA. It would also guarantee a logbook for the SCCA should the owner ever want to go to the dark side.

[civicrr]

The CCR allows for minor variations in tubing thickness.

 

15.6.18 Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver. Note: There is an allowance of minus 0.010 inches on all tubing thicknesses.

 

As far as chassis stiffening goes, the cage construction rules for Honda Challenge are more liberal than the CCR.

 

4.9 Roll Cage

All cars shall have a NASA CCR-compliant roll cage. Additionally,

1) Any number of additional mounting points may be used.

2) Any number of additional tubes may be used, even for chassis stiffening.

3) Any size mounting plate may be used, subject to material and minimum specifications in the NASA

CCR.

 

 

Having posted that info, I would discourage the use of ultra thin tubing for reinforcement.. On my new race car, the main elements of the cage are .120 & I used .095 for the additional tubing, when they could all be .095. The reason for this is twofold. I have seen cars roll & hit the wall. The thicker tubing will afford me better protection. The second reason is that my car's min. weight requires the addition of ballast to make min. weight....even with the thicker tubing. I knew this when I build it.

 

Never skimp on safety equipment. If you lose because your car is 10lbs heavier, you still would have lost anyway. If you lose because you skimped on safety equipment, you probably won't be racing anymore.

[mikeski38]

Never skimp on safety equipment. If you lose because your car is 10lbs heavier, you still would have lost anyway. If you lose because you skimped on safety equipment, you probably won't be racing anymore.

 

Well put...

[civicrr]

Never skimp on safety equipment. If you lose because your car is 10lbs heavier, you still would have lost anyway. If you lose because you skimped on safety equipment, you probably won't be racing anymore.

 

Well put...

 

Oh yeah! I should mention that I didn't build my cage alone. Mike Lock is a good friend of mine. We did the cage together & it came out great.

 

Admitedly, there are some less than stellar welds but I did the welding, not Mr. Lock His work looks really good with great tube fitment & very nice welds.

[turboice]

As far as chassis stiffening goes, the cage construction rules for Honda Challenge are more liberal than the CCR.

 

4.9 Roll Cage

All cars shall have a NASA CCR-compliant roll cage. Additionally,

1) Any number of additional mounting points may be used.

2) Any number of additional tubes may be used, even for chassis stiffening.

3) Any size mounting plate may be used, subject to material and minimum specifications in the NASA CCR.

 

Important points to consider when discussing permissability - thanks for clarifying. Also the points further expanded on regarding safety are of course well raised.

 

I don't know for certain but I would expect that the Prelude is one of those that is hard to actually get down to weight - though under HC rules it is likely easier than PS/IT for instance. That said, other than the sunroofs the prelude is starting out with a pretty beefy chasis - if the original poster were to want to use one wall thickness lighter on the optional tubes I think the rules permit it and don't think that safety has been sacrificed. At least not relative to only having the required elements with none of the optional tubing. But definitely be in discussions with your region's tech director.