Michael Johnson
Technical Editor
August 1, 2000

Step By Step

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Wild Rides’ Battle Boxes are available for ’79-’98 Mustangs, are made from 1/8-inch steel, and Wild Rides guarantees they will prevent torque box failure. The single hole (arrow) in each plate is where the control arm bolt goes through, and the four holes on the other side are for the bolts that go through the floor. Wild Rides also produces rollbars, subframe connectors and many other custom components. They even build full-on race cars.
The first thing to do is remove the back seat from your Mustang. The upper support plate mounts to the body under the rear seat.
Here’s the torque box area. Specifically, the torque box sandwiches the lower control arm. The torque exerted on the torque boxes from the rear axle twisting makes them tear. As you can see, the torque box is only held in by spot welds. Most people just weld up the side of the torque box where it attaches to the framerail. The Battle Boxes go one step further.
With the rearend jacked up and the rear axle unloaded (be sure to use jackstands to support the car), loosen the lower control arm bolt and remove the nut. Don’t remove the bolt, unless you’re also installing control arms at the same time. If you’re not, only loosen the bolt enough to where you can still install the Battle Box. In order to get the Battle Box in place, we had to back the bolt out until it was flush with the inside of the torque box, install the plate, and then thread the bolt back in. The Battle Box goes in the hole where we have the combination wrench in this photo.
After staring at it for awhile, we finally figured out where the boxes go, but they looked too big to go in the hole. They’re not. The trick is to put it through the hole as shown, then turn it around once inside and line the control arm bolt up with the hole. We had to back the passenger’s side bolt out a little, but not the driver’s side.
After a trial fitting, we painted the Battle Boxes for rust prevention. We used Eastwood Under Hood Black, a quick-dry paint that we had laying around the shop. You’ll notice we opened up the control arm mounting hole. The instructions said that the sheetmetal torque boxes would probably need to hammered out slightly, but we weren’t comfortable doing that, so we elongated the hole to make it fit. This is the driver’s side—the passenger’s side didn’t need as much modification.
Once the paint dried, we reinstalled the Battle Boxes, threaded the bolt back through the hole, and installed the nut. Don’t fully tighten it until the rear axle has a load on it, though.
With both lower boxes mounted, drill four 3/8-inch mounting holes up through the floorboard on each side. The upper support plates go inside the car, under the back seat, and attach to the lower boxes.
Once the lower boxes are installed, we can move topside and begin the mounting process for the upper support plates. We begin by pulling the carpet up and out of the way. Then, using a scraper, remove any sound-deadening material that will hamper the mounting and welding process. Here you can see the top of the Battle Box (arrow, through the hole where the rubber plug used to be) and the holes we had to drill.
Line up the mounting holes and trace where the upper support plate will be welded.
You have to grind the paint off any area to be welded, so we used a die grinder with a Standard Abrasives disc.
Feed the supplied bolts up through the holes and tighten them down.This is a two-man job. Remember to tighten the front lower control arm nuts after you’ve loaded the rear axle. Then just head for your local muffler or welding shop and have the upper support plates welded to the floorboard. That’s it. Installing the battle boxes was easier than we thought once we studied it. Bring on those 5,000-rpm launches!

It doesn’t take much to twist a Mustang’s frame into oblivion. We’ve all seen examples of drag-race Mustangs that have been run hard without any kind of chassis reinforcements. Tell-tale signs are little dents on the roof and waves in the quarter-panels, caused by the flexible chassis twisting under the demands of big power and good traction. Subframe connectors and a cage will eliminate this, but there’s another weak area in the Mustang’s chassis—the torque boxes. It only takes a few 5,000-rpm launches with slicks to start ripping up the torque boxes even on a stock Mustang—but when you throw real power at it, it gets ugly in a hurry.

The torque box is held together only by spot welds, so many people just weld them up by running a bead joining the torque box with the framerail. This practice provides extra strength for the torque box, but you’re still talking about sheetmetal, so the ideal way to sure up the torque box area is to install Wild Rides’ Battle Boxes. The Battle Boxes reinforce the torque box area by strengthening it and greatly lessening flex. Continuous stress on the torque box area from the twisting of the rearend under hard acceleration causes them to tear, but it doesn’t happen all at once. Think of it as an aluminum can. If you twist the ends of the can in opposite directions, it fatigues over time until it eventually begins to tear in half. The same goes for the torque boxes. This condition is more common for Mustangs that have traction enhancements at the rear. The greater the traction, the more stress is exerted on the torque box.

Furthermore, the Battle Boxes provide an excellent base for other frame-stiffening components such as subframe connectors and rollcages. As a matter of fact, you can route your cage’s rear bars to connect to the upper support of the Battle Boxes. The Battle Boxes will go a long way in ensuring that you’re prepared for battle.