With the NHRA's new rules about T-top cars being lumped in with convertibles, I was wondering what is the defining difference between a "ROLLBAR" and a "ROLLCAGE"?

Jeff

 

Maybe someone can chime in who knows a little more, but...I think the rollbar is 6 point, whereas the cage is 8 or 10 point and includes a bar at the top to reinforce the roof and protect the drivers head.

 

I have an 8 point chromoly, but none of it goes to the roof except the main hoop. That rule is ridiculous because if you have ever taken the roof off of a 4th gen. the structual metal is the same roof a t-top car has. The only difference is the composite roof instead of two glass pieces.

 

First, has anyone actually seen an NHRA publication or press release regarding t-tops being treated as "open roof"?

Second, the coupe has side rails on the roof, where the outer edges of the T-tops would be. These need to be cut out to install t-tops. The metal structure of a t-top roof is not the same as a coupe roof.

Coupe, with top composite skin removed

An NHRA "roll cage" is a 5-point structure. Main hoop, behind the driver, and within 6" of the helmet (2 points), a brace on each side from within 6" of the top of the hoop to the rear body structure (2 more points), and a single front brace on the driver's side, passing between the drivers shoulder and elbow (the 5th point). The hoop behind the driver also requires a cross-brace for mounting the harness. As currently published, this applies to converts running faster than 14.0, and coupes running faster than 12.0

An NHRA "roll cage" adds a number of elements. Diagonal braces at the bottom of the hoop behind the driver. A second front brace, on the passenger side. A "halo" between the top of the hoop and the windshield header. Braces from the windshield header portion of the halo to the floor, joining the "front" braces from the hoop. Braces on the floor connecting the bottom of the hoop to the front intersection of the front braces and halo braces. This is a requirement for all stock firewall cars running quicker than 10.00, and the structure must be certified by an NHRA inspector and have an inspection sticker attached to it.

 

Basically, a cage give 360 degree protection.


It's like what Injuneer described. Full roof as well as front and more side protection( down bars) that surrounds you ,and not "just" a roll bar over your head.


Of course more bars can be added two this, but I'm talking about a basic cage . Some have bars between those bars at the top . And also some have lower bars running right across the front middle of the car, across where the stereo in an fbody would be, and or behind the dash. It depends on whats, needed , how fast, and who builds it.

But a cage is just that a cage that surrounds you.... while the roll bar is that rear main bar that runs over and behind your head and protects you when the car rolls , plus a few other bars like either 1 side bar on a (5 pt) or 2 side bars on a(6pt) along with the bars that go to the rear of the car.