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Old 05-19-2008, 01:17 PM
V8 Super Beetle's Avatar
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Roll Bar Question!

Hey guys, I'm new to fabricating a roll bar and have some questions. I understand the basic NHRA standards but when does NHRA standards actually apply (I'm located in Housto, Texas) to the roll cage you have in your vehicle? The intention of my cage will be to help strengthen the chassis up and for protection. The roll bar will be 8 points. My vehicle will be mainly street and will see the track on nights called "Safe Street Night". So I don't actually intend on competing, just having fun with it.

Also, I found some donor 1.75" x .125 steel tubing that has one 180 bend (think of a u bolt) and I was thinking of possibly using it by cutting it in the middle of the bend and welding the needed length to make it my main hoop. Is this a good / practical idea if I don't intend on using my vehicle for competition?

Thanks!

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Old 05-19-2008, 01:33 PM
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You can't (rules) and shouldn't (safety) use spliced tubing.
Continuous runs only.
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Old 05-19-2008, 01:49 PM
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Quote:
Originally Posted by 428ho
You can't (rules) and shouldn't (safety) use spliced tubing.
Continuous runs only.
Makes sense to me! Thanks! I'll just get some 1.75" .125 tubing bent at a muffler shop or a machine shop.
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Old 05-19-2008, 01:51 PM
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V8 Super Beetle, first we need to clarify the meaning of "competition." If you are making a pass on an NHRA member track, you need to follow all NHRA rules- even if you're just making a time trial or a solo run.

As for the actual rules, I copied the following from http://www.nhra.com/contacts/tech_faq.html

When do I need a roll bar or roll cage, and what should it look like?
A roll bar is required in any convertible running 13.49 seconds or quicker in the quarter mile, and in other cars beginning at 11.49. The roll bar is accepted in vehicles running as quick as 10.00 second e.t., provided the stock firewall and floorboard is intact, other than for installation of wheel tubs. The rollbar must be constructed of minimum 1 inch o.d. x .118 inch wall mild steel tubing, or 1 x .083 chrome moly tubing, and must conform to the following diagram:


As for the second part of your question, YOU SHOULD NOT WELD TWO SHORTER BARS to make up your main hoop.

It sounds like in your description you are talking about butt-welding two tubes together to get the required length. This should NEVER be done anyplace on a chassis. The correct way to do something like this (on a non- roll bar part of a tube chassis) is by sleeving the tubes. Both tubes are welded to a tight fitting sleeve at the butt joint as well as plug welded to the sleeve with 3 or 4 rosette welds. But to reiterate NEVER do this on roll bar tubing.

If your car won't go faster than 11.5000000, don't bother with the roll bar.
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Old 05-19-2008, 02:38 PM
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What NovaJohn says is true..Any safety equipment in any car must meet the specs of the current rule period..If it does not then you get sent home to fix it before you come back..Applies to any form of racing..Might as well just bite the bullet and get a rulebook and follow that..

Now how do we project a cars potential performance..?? Lets just say Ole Fred down the way has a car that we know runs high 9's or low 10's on a consistent basis..then some fellow shows up with a car that is similar to the one Fred has..We would suspect that the new car would time in at about the same speed and time so we tech the new car accordingly..

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Old 05-19-2008, 03:00 PM
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Quote:
Originally Posted by OneMoreTime
What NovaJohn says is true..Any safety equipment in any car must meet the specs of the current rule period..If it does not then you get sent home to fix it before you come back..Applies to any form of racing..Might as well just bite the bullet and get a rulebook and follow that..

Now how do we project a cars potential performance..?? Lets just say Ole Fred down the way has a car that we know runs high 9's or low 10's on a consistent basis..then some fellow shows up with a car that is similar to the one Fred has..We would suspect that the new car would time in at about the same speed and time so we tech the new car accordingly..

Sam
So in the case of a 1973 VW Beetle showing up, they wouldn't tech it at all!.......?

All great advice guys! I'm not sure what it'll be running when finished. It's basically a 73 bug body on a shortened S10 frame and the motor that'll go into it will be a mild 283. I'm at the best stage to consider a roll cage and needed advice. I doubt it'll be running 11's but I'm not too sure how the body would hold up if it rolled, or if it was t-boned.
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Old 05-19-2008, 04:05 PM
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I wrote this a while back and then updated it for 2008. Enjoy.
http://www.crankshaftcoalition.com/w...legal_Roll_Bar

Posted by Sam:
"Now how do we project a cars potential performance..?? Lets just say Ole Fred down the way has a car that we know runs high 9's or low 10's on a consistent basis..then some fellow shows up with a car that is similar to the one Fred has..We would suspect that the new car would time in at about the same speed and time so we tech the new car accordingly.."

What I do at Firebird is to tech the car to the E.T. limit it qualifies for according to the rulebook. As I'm walking around the car, I'm observing for parts and/or conditions that will be the limit when I get through teching it. For instance, if I see that the car has no bar or cage, it's automatically limited to 11.50. If it has a bar, but no aftermarket SFI harmonic damper, then the limit is 11.00, because the damper is a required part at 10.99, along with an automatic trans shield and aftermarket axles. And so on and so forth.

If I tech the car to 11.00 and he goes out and runs 10.99 or quicker, then he is done for the night and can't run the car again until he has corrected the parts or conditions that have limited the car. The next time I see the car, it must qualify for the quickest E.T. he ran last time out. After one or more of these sessions, the car is legal and the owner can come out and enjoy him (her) self.

Now, if I write the racer a laundry list, I'll work with him to make a few changes at a time until the car is legal, starting with fixing the most serious infractions first.

What you have to understand is that there are too many hungry lawyers out there and it is incumbent on me to protect the track from lawsuits resulting from someone getting injured or killed as a result of not meeting the rules.

Last edited by techinspector1; 05-19-2008 at 04:21 PM.
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Old 05-19-2008, 04:29 PM
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Quote:
Originally Posted by V8 Super Beetle
So in the case of a 1973 VW Beetle showing up, they wouldn't tech it at all!.......?

All great advice guys! I'm not sure what it'll be running when finished. It's basically a 73 bug body on a shortened S10 frame and the motor that'll go into it will be a mild 283. I'm at the best stage to consider a roll cage and needed advice. I doubt it'll be running 11's but I'm not too sure how the body would hold up if it rolled, or if it was t-boned.
No we would tech the car and then send you home with a list of stuff to get done before you show up next time..Most tech guys that I know of carry a license or credential issued by the race organization..So go find one of these guys and have him look over what you are doing..Most of them are happy to do this on a car under construction..You may need to get it on a trailer and take it somewhere to have this done as most of them are volunteers..Main thing we want is for the driver/owner to have a good time and go home with all the body parts he came with intact and attached in the proper place..

Now saying all this I am not all that current with NHRA or drags.. i am a bit more tuned into Bonneville or El Mirage and I have done things with the road race scene..At Bonneville the V-8 beetle would most likely be placed in the altered coupe class..Most likely with a 283 this car would be a D-altered class..The current record in this class is 229.935 MPH so tech would go accordingly..

In any case if the intent is to run the car at a sanctioned event the it is a good idea to pay the dues and join that race organization, get the rulebook and meet some of the experienced guys that can help you get thru the tech part so you can run..

Sam
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Last edited by OneMoreTime; 05-19-2008 at 05:05 PM. Reason: More stuff to say
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Old 05-19-2008, 04:36 PM
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Sounds good to me! I'll have it looked over when I get to building the roll bar.
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Old 05-20-2008, 05:19 PM
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Follow the rules that the guys gave you above; but I really think whatever you do rollcage-wise, will be for your own peace of mind and personal safety.

I am surely not trying to belittle you or your car in any way, but I honestly don't believe it would run below 11.5 seconds, as you're building it now.

I'm guessing it's going to weigh somewhere around 2500 pounds, maybe more.
With a really radical 283, maybe. Doubtful.

You can't overkill your safety. The VW bodies are pretty stout, and I've seen them roll over with very little damage. But it's a rod! Build it that way. You may want to put a thumper motor in it someday, and then you'll need the cage.
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Old 05-20-2008, 06:50 PM
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I build alot of roll cages for different vehicles, But for the most part its all SCORE Off Road Rules. I dont know about NHRA rules but you might want to check and see if mild seamed steel is an authorized material? I do everything out of DOM or 4130. Just a thought before you get to far down the road.
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Old 05-21-2008, 09:42 AM
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Quote:
Originally Posted by dalesy
Follow the rules that the guys gave you above; but I really think whatever you do rollcage-wise, will be for your own peace of mind and personal safety.

I am surely not trying to belittle you or your car in any way, but I honestly don't believe it would run below 11.5 seconds, as you're building it now.

I'm guessing it's going to weigh somewhere around 2500 pounds, maybe more.
With a really radical 283, maybe. Doubtful.

You can't overkill your safety. The VW bodies are pretty stout, and I've seen them roll over with very little damage. But it's a rod! Build it that way. You may want to put a thumper motor in it someday, and then you'll need the cage.
Thanks for the advice! I'll do just that cause I agree that you can't over due safety. It'll be interesting to see how much it'll weight at the end and what'll run.
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Old 05-21-2008, 09:49 AM
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Quote:
Originally Posted by Metal Twister
I build alot of roll cages for different vehicles, But for the most part its all SCORE Off Road Rules. I dont know about NHRA rules but you might want to check and see if mild seamed steel is an authorized material? I do everything out of DOM or 4130. Just a thought before you get to far down the road.
Thanks for the heads up!
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