Per Schroeder
Per Schroeder SuperDork
6/11/12 9:32 a.m.

A roll cage is one of the defining characteristics of a race car. This collection of tubes and gussets is not just distinctive; it provides the measure of safety that drivers need to do their job. A cage also keeps the car stiff and strong during a season of racing.
There are three ways to get a competition-legal cage into a race car: bolt in a prefabricated kit, weld together a pre-bent kit, or have a custom-built cage tailored to a specific car. There are also a couple of choices regarding how everything is assembled, as both MIG and TIG welding are prevalent among cage builders.
Generally speaking, TIG welding looks better and offers more consistent and cleaner welds. TIG welding also produces fewer sparks, which can be a plus when working around soft interior components. (Although in a perfect world the car’s seats, carpet and interior panels have already been removed before the roll cage installation begins.)
Bolt-in kits used to be the most common cages found on the amateur level. These cages are inexpensive, easy to find and can be installed in one weekend with only a 3/8-inch drill and a ratchet set. Since most come already painted and ready to go, they offer a quick and easy way to make your car safer.
One downside is that the bolt-in kits are usually built with big tolerances, and as a result the gaps between the roof and the cage are generally larger than necessary. This can lead to less room inside the cage and less crush space in the event of a crash.
Bolt-in cages usually also bolt to the horizontal surfaces of the car’s floor pan, as they’re not welded into the sills. As a result, a bolt-in cage can tear through the floor’s thin sheet metal during a hard impact. Bolt-in cage kits start at about $700 and are legal for most forms of club-level, production-based road racing and some rally events.
Weld-in kits cost about as much as the bolt-in setups and come with all of the required tubing. All of the bends will have already been performed. The tubing is generally left a little long on some portions, while other sections are already fish-mouthed so they can be welded up quickly and cleanly. You can figure on spending at least another $500 to have this kind of cage welded into your car, but bear in mind that any changes or additions can quickly add to that.
A custom-fit cage can cost quite a bit more than the other types, with prices typically starting in the $1500 range. While that price may seem like a disadvantage, it’s probably the only compromise you’ll make if you go this route.
A good custom-fit cage can maximize both the safety and rigidity of the car because it’s bent and cut as large as possible to fit within the confines of the passenger compartment. The farther the cage is from the occupants, the less likely it is that someone will come in contact with it during a collision. A larger cage will also be able to deform more before encroaching on the passengers.
On the performance side of things, a properly built cage can dramatically improve a car’s performance. If allowed by the rules, the cage can be welded to the car’s body, which greatly stiffens the structure; if the rules prohibit tying the cage’s bars to the car’s body, it’s still possible for a custom cage to press against the roof, door sills and A-pillars, providing similar benefits. (We’ve even heard some cars squeak during cornering as the chassis flexes around the cage in key locations. That’s a tight fit.)
Bolt-in and weld-in kits are available from companies like Autopower, Safe Drives, and Kirk Racing Products and can be truck-freighted to your door. Custom cages are more of a regional proposition, unless you’re willing to have your car trucked to the builder.
When discussing a cage with that builder, it’s also best to hand them a copy of your sanctioning body’s rulebook. This should ensure that the final product is both safe and legal.

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