The Basics

At the surface, a roll bar and a roll cage are designed to accomplish one very critical goal — to keep the driver safe should they be involved in an accident; particularly a crash that involves the shiny side down. But as chassis builders found early on, there’s more function to that puzzle of bars than just safety, which we’ll get into later. As most of our readers know, a roll bar and a roll cage are not the same thing. Same purpose, different execution.

NHRA Regulations You Should Know

So even though the rules say you don’t have to run it, we really suggest you put at least an 8-point in any car that’s going to be raced. – Jim Wright

The National Hot Rod Association, the premier governing body in the sport of drag racing, outlines a number of requirements for roll bars and roll cages for racers competing at sanctioned tracks and events the world over, based on elapsed time and, in some cases, on speed.
Vehicles running 11.00 to 11.49 in the 1/4-mile or 7.00 to 7.35 in the 1/8-mile (including those with T-tops), convertibles running 11.00 to 13.49 (7.00 to 8.25), and dune-buggy-type vehicles running 12.00 and slower are required to have a roll bar installed in the vehicle.

Stepping up the performance ladder, a roll cage is mandatory for any vehicle running 10.99 (6.99) or quicker or exceeding 135 mph. In any full-bodied vehicle however that maintains an unaltered firewall, floor, and body running between 10.00 and 10.99 (6.40 and 6.99) a roll bar is permitted in place of a roll cage.

All roll bars/cages constructed of 4130 chromoly tubing must be welded using an approve TIG heliarc process, while mild steel must be done with an approved MIG wire feed or TIG heliarc process. Grinding and plating of the welds is prohibited, so keep these points in mind if you’re a do-it-yourselfer.

The 2012 NHRA Rulebook has 12 pages in the General Regulations section that pertain to frame requirements, which is far more than we could ever outline here in detail. If you’re considering building a roll bar/cage yourself, we’d suggest if you’re not already an NHRA member, to either get yourself signed up or pick up a copy of the NHRA Rulebook, which is available for $10 from the NHRA Store online.

Something to keep in mind when you’re in the market for a roll cage is the fact that what’s designed to save your life in a dedicated race car isn’t necessarily optimum for a car that spends all or most of its life on the street. Most chassis builder, including those we spoke with in this article, generally build their roll bars/cages to NHRA specifications regardless, but these chassis builder also know there are safety discrepancies between a street and a race car.

Like anything else, you get what you pay for in a roll bar/cage. Go to the track, check out the quality of the work you see, and compare prices amongst those shops. The ones that charge more may not always deliver the better product, and vice versa, the cheap shops aren’t necessarily rolling shoddy jobs out, either.