Thread: Pro Street Nova help

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Originally Posted by techinspector1

My best advice is to read and study the drawings in the current NHRA Rulebook (available from Summitracing), then buy the legal-sized tubing and measure every stick of it, O.D. and wall thickness. Rent a bender and bend up your own cage. Tack it together, then call a certified aircraft welder to come out with his mobile rig and weld it up for you. It'll be the cheapest money you ever spend on the car. If you plan to be able to seat passengers in the rear, you will need some sort of removeable cross bar (the bar that runs laterally across the car at your shoulders).

The rules don't make provision for a removeable bar, but if you do it nicely with spring-loaded cup-slider ends on it, I don't think any technical inspector worth his salt will fail the car in tech. I look for purpose and intent as well as adherance to the rules.

If you do have someone else bend it up and install it, make sure they have done NHRA bars and cages before and understand how the whole mess should go together. It has been my experience that shops that do roundy-round cars or cars from venues other than NHRA drag racing just do not understand the differences in bars and cages for drag racing.

You'll also want to get the "C" bars out of the way of rear seat passengers. The rules allow one (read 1) bend in the C bars, so I would run them off the "B" bar (main hoop) and straight back along the underside of the roof, then make one bend in them at the shelf panel, to go into the trunk area. I have attached a pic of straight C bars with rear upholstery, so it can be done.

Here's an article that I wrote for the Crankshaft Coalition wiki a couple of years ago. Use it as a guideline, along with the current NHRA Rulebook and you'll be fine.
http://www.crankshaftcoalition.com/w...legal_Roll_Bar

I have a keen interest in seeing fellows put the bar or cage in a car properly, to the point that I will give you my cell phone number so you can call me and get your questions answered as you're building it.

Let's get the lingo started properly. As the car is viewed from the side, the front post that goes from the body to the roof at the windshield is the "A" pillar. On a sedan, the post that goes from the body to the roof at the middle of the car is called the "B" pillar. The post that goes from the body to the roof at the rear glass is called the "C" pillar. Therefore, with a rollBAR, you would be using a B bar and two C bars. With a rollCAGE, you would be using an A bar, a B bar and two C bars, along with halo bars running up against the roof at the top of the side windows to connect the A and B bars. The Bar or Cage is the most frequently mis-engineered component in any car. When I used to find a properly built bar or cage, I would call all the other tech inspectors over to look at the car. All of us would congratulate the builder and make a good friend at the same time. This is how you get through tech easily every time. Build the car according to the Rulebook.

Richard,

Please let me get on my soap box for a minute.How well a roll bar/cage is built is totally dependent on how well is it fish mouthed and the seams not being too wide to weld.Many shops around here won't accept work that has been tacked together because of the pcs not being correctly cut to length and poor fish mount fits.A weld is to fuse the metal together and not glue the pcs.The tighter the seam,the better and stronger the roll bar/cage is.Yeah I know when your order the parts,you get a main hoop and a box of tubes basically.

A story from my childhood is I went over to a friend's shop when I was a kid.He was welding a roll bar in his circle car race car that he was building.We worked all day in his father's shop and truly never got the pcs to fit properly.He just filled in the gaps.You know how multi angles do come into play.Well his father came home from working as a welder.He looked at what we have done which I got to say looked pretty good.He said to his son that he WAS NOT GOING TO RACE THAT CAR LIKE THAT!!.My friend started to argue with his father and his father when over to the tool box and got a hammer.Not that big of a hammer or not that big of a swing and hit what we had welded.The tubes fell apart.

On the other hand I later built a 1975 Monza town coupe.It was a Don Hardy back haft kit with a 8 point roll bar.While the back haft square tubes where just welded into the car,you could hit them with a hammer and they would ring like a bell.As we added more and more pcs of the roll bar in with good tight seams the back haft tubes got stronger until the last bar tube was finished and then when you hit it with a hammer,all you heard was a thud.That car yrs later has gone threw god knows how many wheelstand cycles without a single issue.I think the safety issues of a roll bar aside,that roll bar/cage adds to the suspension/frame strength tie'ing the front to to the back of the car.

So what am I trying to say??.Well if a guy doesn't have the equipment or basic metal working skills,it is far better for him to farm out the part of a project.Jegs has long ago closed it's frame install shop,but maybe if this O/P contacted Jegs,they could tell him who to contact in Ohio.