Bolt in cage?

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I want to know why NHRA wont allow oval tubing ? Chrome moly should be plenty strong enough . That would give more head clearance and keep it hidden .
 
motorpirate said:
NHRA 4:10 says cars without a frame must have roll bar secured by 1/8 inch thick 6"X 6" plates on both sides of the floor secured with at least 4 3/8 bolts.
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There is some incorrect information in this thread. If installing a cage per nhra( not a roll bar) those plates have to be fully welded to the floor. Bolted plates only allowed for a bar.
Also there is no height requirement for the hoop. The NHRA rule book states that the drivers head must be 3 inches below the height of the hoop when sitting in the seat. The height of the seat and driver are variables for compliance with the rule.
 
When I put my 6 point in, I drilled holes in the floor to drop the main hoop down to weld the struts coming off of it , taking care to have them tacked in the right position to start with.
Then raised it up and onto the 6'' welded plates.
No big deal to reweld the holes up .
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Pretty trick I say!!

Standard procedure for a chassis/race fab shop.
 
Marcohotrod said:
sounds like the rulebook is saying a unibody car is not safe with a roll bar welded to sheetmetal. my insurance company for the street said no rollbar - I said jeeps have rollbars! and mine is well padded. Is there any data that on the street with a padded bar and a 5 point harness and no helmet no rollbar is safer. I have seen some bad street car crashes and said looks like they may have lived with a rollbar and seatbelts
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The NHRA rule book says welded to the plates that are bolted to the floor. The plates spread the load around the sheet metal.
A harness on the street can cause a neck injury. It was recently brought to my attention that the purpose of airbags is to prevent neck injury. The reason that racers are using the HANS device is that the drawback to a harness in a frontal collision in a car without airbags is neck injury. Helmets, rollbars,and harnesses have no place in a street car. IMHO.
 
a 5 point harness is a seat belt-a law to use in my state. I do not wear a helmet and do not have an airbag in my 1970. In a frontal collision with high back buckets I do not think my head will hit the rollbar
 
Marcohotrod said:
a 5 point harness is a seat belt-a law to use in my state. I do not wear a helmet and do not have an airbag in my 1970. In a frontal collision with high back buckets I do not think my head will hit the rollbar
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I was referring to a head on collision where a 5 way harness restrains your body, but allows your head to whip forward.
The HANS device restrains the head from whipping forward.
Air bags do the same thing. As a Canadian who frequents Florida, I am aware that the laws differ from state to state. I routinely see people riding motorcycles with no helmet and a pair of sandals on.
Legal ? Yes. Is it wise? IMHO no. To each there own.
In a rollover accident your head could still hit the side bars.
Harnesses stretch significantly in an accident.
 
Famous Bob has the correct answer... we did it like that on our dirt cars 40 years ago.

And, back then, a unibody car required a bolt in four point cage. There were no mig welders back then and finding a good welder to do your cage was tough... mostly had to pay up the wazoo.


Our tracks closely inspected every cage going as far as drilling an inspection hole to measure wall thickness (.125 was the spec). Some guys gas welded them and that was good. We had a army surplus WWII Lincoln gas powered rig. Hard to plug in an arc welder when your house has 40 amp service.
 
Back in the late 1970's we needed a five point bar to run 12.50's at my local track. My street car Duster had gone 11.80's so I put in a plated bolt in four point cage from Summit and a buddy of mine welded a pinned driverside bar to ease getting in and out. I remember this like it was yesterday the issues I had drilling holes for the plates. My Dad was an Electrician so he had a VERY powerful Milwaukee 1/2 inch drill. Well being young and dumb I plugged drill into the trouble light. Drilling at an angle because of the rollbar the bit grabbed when the bit entered the plate under the car. As the drill grabbed it spun and I hit the button to hold the trigger in. Before I knew it I had a badly sprained wrist and shattered light bulb all through my Duster form the cord wrapping around the drill. Lesson learned, THE HARD WAY.
 
pittsburghracer said:
Back in the late 1970's we needed a five point bar to run 12.50's at my local track. My street car Duster had gone 11.80's so I put in a plated bolt in four point cage from Summit and a buddy of mine welded a pinned driverside bar to ease getting in and out. I remember this like it was yesterday the issues I had drilling holes for the plates. My Dad was an Electrician so he had a VERY powerful Milwaukee 1/2 inch drill. Well being young and dumb I plugged drill into the trouble light. Drilling at an angle because of the rollbar the bit grabbed when the bit entered the plate under the car. As the drill grabbed it spun and I hit the button to hold the trigger in. Before I knew it I had a badly sprained wrist and shattered light bulb all through my Duster form the cord wrapping around the drill. Lesson learned, THE HARD WAY.
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LOL , reminds me of one time I was mounting and bedding 10 ft lathe , drilling the mounting holes in concrete floor w/ a 3ft air drill , changing the bit , told helper "dont hit the trigger" guess what , he did , broke the knuckle on first finger on right hand. My fault for not unplugging the air line ., didnt make me feel any better .
He was about a dumbass anyway , quit a few weeks later to go to college .
 
famous bob said:
LOL , reminds me of one time I was mounting and bedding 10 ft lathe , drilling the mounting holes in concrete floor w/ a 3ft air drill , changing the bit , told helper "dont hit the trigger" guess what , he did , broke the knuckle on first finger on right hand. My fault for not unplugging the air line ., didnt make me feel any better .
He was about a dumbass anyway , quit a few weeks later to go to college .
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Dog gone machinery can bite you in a split second. My most dreaded job being a Millwright in the steel mill was having to go on “glove searches” to find someone’s finger that’s been pinched off.
 
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