Project Mini Stock, Part II

Wes Filyaw sizes up another...        read full caption Wes Filyaw sizes up another door bar as he constructs our rollcage. We had our Butler Built seat mocked-up in place because Wes is putting just one bend in the door bar for strength, and we wanted to make sure we had enough elbowroom.

We used 2-inch square tubing...        read full caption We used 2-inch square tubing as frame support rails. They ran the length of the car, which required a bit of cutting. Wes alternated his welds above and below the tubing to keep heat from causing any warpage.

To add rigidity to the back...        read full caption To add rigidity to the back half of the car, Wes snaked our square tubing through the inside of the rear framerails on our Mustang. As you can see, a lot of angle cutting is involved to get everything to fit together snugly but, if you want a good stiff car, this is the way to go. We cut off everything behind the shock mount and stopped with the tubing there, too. A plate is welded onto the end, and we’ll use lighter-weight steel to fabricate the rest.

Instead of stopping at the...        read full caption Instead of stopping at the firewall, we went through it to better lock everything in place. Doing it this way is more time consuming because you want the hole just big enough for your tubing, otherwise the weld won’t be strong. We’ll have to cap off the end later to keep mud and dirt out.

After the frame supports are...        read full caption After the frame supports are in, the next step is locating the main four points for the rollcage. The rest of the supports are built in afterward. Notice the space between the firewall and the downtubes on the front. Because we don’t want to add weight by making the ’cage any bigger than we have to, we’re moving it backward along with the driving position.

A piece of round tubing is...        read full caption A piece of round tubing is added between the stock framerails to add some lateral stiffness. If you look closely, the boxing that extends beyond the framerails is welded to a flat plate just behind the shock mounts. Hopefully we’ll never need it; but the idea is, in the event of a hard hit from the rear, everything is expected to bend up to the plate, while our center section stays intact.

Once the rear wheelwell is...        read full caption Once the rear wheelwell is cut away there isn’t much to support the upper shock mounts. To correct for this, Wes put a curve into two short pieces of tubing and connected them from the shock mounts to a chassis support tube.

Nothing fancy about this tubing...        read full caption Nothing fancy about this tubing bender, but it does the job. Because there is no gauge to help Wes with his angles, he is in the habit of using a coat hanger inside the car to find the curves he needs and then tracing them onto a big piece of cardboard (or sometimes even the shop floor). When the piece of tubing he’s bending matches up with the template, he knows he’s ready to roll.

The ’cage we built to...        read full caption The ’cage we built to support the fuel cell is welded into place inside our frame. The cell will be bolted to the frame, and we’ll add straps across the top later. We’re using an eight-gallon cell from ATL, which should be plenty given our engine size and the short races we’ll be running (20-35 laps).

After we finally got our Project Mini Stock stripped to the core and ready for its rollcage, we had to make another one of those decisions about tempering our enthusiasm with our better sense. We (collectively) were smart enough to realize building a rollcage that we’re willing to stake our lives on wasn’t within our combined mechanical and technical capability, so we loaded up what was left of the car and hauled it off to an expert for this part of our Mini Stock’s construction.

This won’t be the last time we’ll face paying experts to build a portion of this car. But in matters of race car safety, like constructing an effective and safe rollcage, I highly recommend you talk to other racers and find a trusted race car constructor to do these sorts of tasks. Don’t scrimp on racing safety; put ample money in your budget for it. We want readers to be around to follow along on future projects, even as we want to be around to build them.

For expert help on the rollcage, we turned to Wes Filyaw and NASFAB in Concord, North Carolina. Wes has been racing Mini Stocks for years and is one of the people in our area who specializes in building that type of car. Wes was familiar with our racing class’s rules and will build a rollcage that is safe, strong, and conforms to the reg’s.

We are also lucky to have the racing support advantages that come with living in central North Carolina, the hub for stock car racing. While most chassis and ’cage builders will do it for you, we decided to order our raw materials. Stock Car Steel, located in Mooresville, North Carolina, provides raw materials to almost every NASCAR Winston Cup and Busch team in the area, but it also delivers to any race shop within its range—and there are plenty besides the majors. The great aid to the local racer by this company is it doesn’t require large minimum orders like most industrial steel distributors. If you can find an outfit like this close to you that will deliver, it’s definitely one way to go to get the rollcage materials.

We ordered 20 feet of 2-inch square tubing, 40 feet of 1-½-inch 0.095 DOM tubing (Drawn Over Mandrel tubing: It is seamless and consistent in diameter), and another 60 feet of 1-½-inch 0.083 DOM tubing. It was waiting for us at the NASFAB shop the next day. We also ordered a box of 50 gussets from A&A Manufacturing to further strengthen the center section of the rollcage.

Seat Fit Concerns

One part of our car construction plan, because we will be racing on dirt, was to move the driver’s position as far back as possible to get more weight over the rear wheels to aid in balancing the car. To make sure we didn’t get our ’cage dimensions incorrect, we went ahead and purchased a racing seat, shoulder and head restraints, and mounting hardware from Butler Built. We mocked up the seat regularly in the construction process to try out different driver locations and to make sure the rollcage left the driver enough room to work.

When doing this, don’t forget to find your seat height and be sure there will be plenty of clearance between the driver’s head and the roof bar just beneath the driver-side window. Under no circumstances do you want the driver’s helmet to be able to make contact with that bar while strapped into the seat. This sounds obvious, but we’ve seen seats installed incorrectly without taking this into account too many times. Again, that’s why it’s prudent to rely on an expert chassis builder to construct your rollcage—they know the pitfalls and how to build a well-constructed and safe ’cage.

Project Mini Stock, Part I
Project Mini Stock, Part III