I am looking for some pictures of some of the roll cages that are NHRA certified. I am mainly wanting to see what you guys are doing with the rocker bar and "D" bars area. I have a copy of the rulebook, I just want to get an idea of how it is being done.


Thanks.

 

here is what i was told was the correct way to do it. this is jeff evans car. but i was also told they want to start having it go rocker to rocker, instead of hoop to hoop.

 

Mine is just like above and it's fine.

 

I'm glad someone posted this. I know there have been a few threads like this in the past, but I was under the impression that nhra changed what they were looking for regarding the Dbars.

I have seen people say having it like the picture above is fine and others saying it needs to go rocker to rocker. I'm not sure what is the correct way.

I never really looked into it until now, as I begin my transformation to a 10 pt.

 

Yeah I was also trying to figure it all out. I wouldn't think jeff would be wrong.

 

check with whoever is going to inspect it. i know some guys around here have let existing d bars like that go and have advised the owner to change before their next inspection. most chassis shops are aware of what needs to be done and are doing the bars rocker to rocker.
-Roger

 

^^ thats my understanding also. that it needs to go rocker to rocker now.

 

Read the rulebook. It needs to go rocker to rocker. And S&W instructs that the bar must go rocker to rocker, and cant touch or be attached to the main hoop. With the lateral bars tying into it.

The lateral (D) bars are just there for extra support or enforcement to keep the main hoop from going through the floor. Since we dont have a frame, or a tunnel built strong enough to keep a driveshaft from coming through, the rockers are the next strongest attaching place. If you tie the rocker bar into the hoop like above, youre just triangulating the main hoop. Not actually attaching it to the chassis at more points. So you really dont have lateral support bars now. The D bars just triangulate. Or at least thats what my logic tells me.

I havent had mine cert'd yet (didnt think I would need to, and my local track didnt call me out for going >135), but this is how I did mine...



And this was probably easier to fab, than the above. Didnt have to notch the pipe. Just cut it, grind it to the right angle so it sat seamlessly on the plate, and done.





As far as tech/cert'ing it, it wouldnt matter. We still have guys running the D-bars to the tunnel, with no rocker bar, and passing. So I wouldnt be surprised if the above cage got cert'd as well.

 

that's how the one in my shop is and nhra division 6 tech said it's OK

 

Plus, figure its a 10 POINT cage. ASFAIK, thats 10 points that tie into the frame/chassis.

2-Main Hoop
2-Rear Bars
2-Door Bars
2-A-Pillar Bars

and 2- Lateral/Rocker Bars.

If you tie the rocker bar into the main hoop, and the lateral bars into the rocker bar, you no longer have those 2 points on contact.

Heres a link to S&W instructions for installing their roll bars/cages. At the VERY BOTTOM, there is a diagram, showing and instructing you how to do the rocker bar for FWD unibody cars.

http://swracecars.com/Files/RBRCinstructions2011.pdf

And this is out of the 2011 NHRA Rulebook.

"Section 20, page 27 General Regulations
“D” bar installation for full-bodied cars: For front-wheel-drive cars,
with complete OEM floor (from the firewall to the rear of the trunk)
and rocker/sill boxes, the 1 1/4-inch x .058-inch CM (.118-inch MS)
“D” bars (when required; i.e., when the main hoop is not welded to
the frame) may be welded to a 1 5/8-inch x .083-inch CM (.118-inch
MS) crossmember welded to the rocker/sill box via conventional 6-
inch x 6-inch x 1/8-inch-thick plates."

Link to 2011 Rulebook
http://www.bremertonraceway.com/2011...20Rulebook.pdf

 

Thanks a lot guys for all the responses.

I was told that the bar must go rocker to rocker and not connect to the main hoop, which is also the way it seemed to me from the rulebook.

I was just wanted some confirmation.