A rollbar or rollcage serves two purposes: One is to accommodate the safety rules of a sanctioning body, and the second is to increase the car's rigidity. Both of these are important reasons to add the tubing, but because our '66 Mustang's primary function is a street car, improving the car is a higher priority than satisfying the tech inspection for a race. This '66 will see the track, but in an open-track non-competitive situation where a 'cage isn't required, let alone measured or inspected.
Step one is to fit the plates...
Step one is to fit the plates that the tubing will connect to the floor with. The front plates are a simple fit that sits flat on the floor up to the edge where the firewall connects.
All Mustangs are of a unibody construction, meaning there isn't a separate frame assembly, but rather it's formed into the sheetmetal structure of the body. This makes it cheaper to produce and lighter overall. This also makes it susceptible to body twist, which is inherently bad for performance and for the car.
To make this project an easier pill to swallow, we wanted something that was pre-bent, so that we'd be responsible for just cutting, fitting, and welding. We found our kit in Chris Alston's Chassisworks' catalog: It's pre-bent to fit '64-68 Mustangs and '67-68 Cougars. It's made from 1 5/8-inch HREW (hot rolled, electric welded) steel, but it is also available in DOM (drawn over mandrel) for a higher price. For our purposes, it made more sense to go with the first option. The main hoop, windshield bar, and front bars were pre-bent. The rest of the tubes needed to complete the 'cage are straight, and were provided in extra-long length with the kit. This way we've got a little freedom on how we would like it to fit. When you don't need to follow a rule book, you can tailor the fitment to your own needs. In our case, we wanted to retain the back seat unmodified, and have the front driver and passenger seats easily accessible, since above all it's a street car. To do this we would use Chassisworks' swing-out kit that allows the door bars between the main hoop and front bars to swing out.
When cleaning the metal to...
When cleaning the metal to prepare a fit for the main hoop's plates, we discovered some rust damage. Before going any further, we repaired the floor by MIG welding in a patch panel.
As far as the installation goes, this is not your mom's arts and crafts project. This was an intense project that required a lot of work and patience. Since the Mustang's move to Northern California, it resides at Dominator Street Rods in Tracy. Here, the youngest of Dominator's staff, Tyler Jones, helped us out a lot. Much of this project is a two-person job; you'll need to have one person hold a couple of bars in place while the other tacks it in with a welder. The end result was much nicer than we had braced ourselves for. One thing we were concerned about was discovering how well a "pre-bent" kit would fit, and it fit pretty darn well; the problems we had were self-produced. You can expect to spend about three eight-hour days on this to get it from the shop floor, to painted and in the car, with a difficulty level of seven out of 10.