Our team has steadily been working on what was previously known as the “Evil 8.5” project car – a Fox-body Mustang that previously competed in the Outlaw 8.5 drag racing class. Recently, the project took a turn. The team behind the beast decided that they wanted the flexibility to race in more circles, so they decided to revamp the Fox into an X275 car. Along with the physical changes, the Fox’s name was changed to simply “Project Evil.” You can read more about the car’s journey here, but today, we’re bringing you a portion of the build that most, if not all, Fox-bodies built for drag racing undergo at some point.
Team Z Torque Boxes
If you’ve ever owned a high-powered drag car, you know that stock torque boxes are grenades waiting to explode. Torn torque boxes are no joke. They’re the result of hard launches, and can easily turn a Fox into scrap metal. In addition, stock torque boxes give you limited ability to create the suspension geometry that you want when lowering the car to optimize ride height.
Seeing as the Project Evil Mustang is set to make about 2,200 horsepower, the installation of new upper torque boxes was a vital step in the build, in an effort to make sure the chassis can handle this ridiculous level of power.
If you’re looking to make any amount of power, you should strongly consider replacing your torque boxes. It’s possible that they are already damaged from years of abuse on the street or the strip.
Team Z’s upper torque box reinforcement kits are designed for 1979-2004 Mustangs, and allow for easy adjustability in respect to suspension geometry not offered when stock. According to Team Z, this kit can lower 60-foot times, improve traction, and offers more adjustment than any other torque boxes on the market. They are tied into the frame for extra support, and feature a lightweight and high-strength design from 4130 chromoly and mild steel, and offer easy instant center adjustment and ease of location and installation. Micro-fine adjustments of .125-inches are maintainable with this kit, and all grade 8 hardware is included. They were designed and are made in-house at Team Z headquarters in Michigan.
“When we set out to build an upper torque box replacement, we wanted to build something with more adjustment than anything else on the market,” Team Z owner Dave Zimmerman told us. “Everyone was asking for it.”
These torque boxes provide significant strength in a pressurized area that is affected by hard launches and twisting. They also weigh less than stock torque boxes, providing weight reduction.
Four-link geometry is of utmost importance in drag cars, and these torque boxes are super helpful in establishing the correct geometry. While the upper bar allows for .125-inch adjustability between each hole, the bottom torque box is equipped with four holes for adjustment. This level of adjustability will allow Project Evil to have its instant center properly set up (this is height and length) and will also allow for the ideal percentage of anti-squat. All of this comes together to determine how Project Evil is going to react when launched. Keep in mind that these factors will all be determined by the individual combination, including horsepower, launch, transmission, and more.
With the radial 275 that Evil uses, we want a higher degree of anti-squat to plant the tire early in the run. The upper torque box gives us the ability to get the upper bar angle right.
The kits are offered in two styles. The first is a narrowed race-style setup requiring the use of lower control arms with heim joints on both ends, and designed to work with coilovers. The second is a standard setup, accommodating stock-style width control arms, designed to work with springs and shocks in the stock location. The narrowed race-style setup was the perfect fit for Project Evil.
Prior to installation, the team had already installed Team Z’s lower torque boxes and had a Team Z Fab 9 rearend housing on-hand, making for even more adjustability.
Keep in mind that this kit is designed to work with a conventional upper control arm, so anything longer or shorter will not work. For example, it does not work with Team Z’s own relocated upper control arm. It also requires the addition of Team Z’s coilover mounting kit (which comes with the mini-tub kit used on Project Evil), but more on that later.
It’s important to note that the position of the coilovers is also critical to the suspension setup.
Ideally, they should be set perfectly perpendicular at the desired ride height. Coilover travel is also a huge factor when it comes to drag racing suspension setup. With a drag radial, having the correct amount of extension is important. With our Menser/Afco shocks that have a total of seven inches of travel, at ride height, we will have more than five inches of total possible extension.
Each individual application requires something different, so it can kind of be a trial and error process to figure out what works best. Shock valving, spring rates, and suspension travel (compression and extension) play a huge part in the success of a correct launch. In addition, a rear anti-roll bar is a must for a drag car. It helps with body roll (sometimes known as the “g-body shuffle”), letting the car put the power down evenly, with minimal motion transferring through the body. It is of utmost importance to make sure that the end links and anti-roll bar diameter are sufficient for the weight and power level of your application.
“With the desire to have the ‘in-the-weeds’ look and stance, adjustability is essential in order to get suspension geometry set up correctly,” Dave explained.
As you can see, there are a lot of factors which affect how suspension works, including power level, transmission type, weight, tire size, and the way the track is prepped. This means that this particular installation should only be handled by a seasoned chassis builder, being that there are many critical factors involving the success of your 4-link race suspension setup.
Welding Skills Required
The actual installation of the torque boxes is relatively easy, but definitely requires solid welding skills. It was also of utmost importance that Project Evil was on level ground during the installation so that the torque boxes could be welded into the precisely correct location. Of course, the rear wheels and tires had to be removed to gain access to the torque box location before installation could begin.
The Team Z rear also had to be removed before the stock torque boxes could be cut out. Since Project Evil has had stock upper torque boxes up to this point, this was easy. The spot welds were drilled out with a spot weld drill bit. If you’re working with a canvas that has already had aftermarket torque boxes installed at some point, removing them will probably require a torch and plasma cutter.
The area should be cleaned and ground before welding the new boxes in in an effort to create the strongest possible weld.
While the team had already replaced the lower torque boxes, the upper torque boxes were done at a time that allowed them to be tied into the roll cage for reinforcement.
After cutting the stock boxes out, the Team Z replacements slid into place easily. They were clamped into place, and measurements were taken to ensure proper placement – front to back and up and down. It’s important to note that once things are welded, it makes correcting mistakes much more difficult, so no amount of measuring is too much. Project Evil’s launches depend on these measurements. An improper measurement (even by a hair) will throw off the entire 4-link system, causing issues on the starting line.
Once this round of measurements was complete, the boxes could be tacked into place before a final round of measurements ensued. Finally, a MIG welder was used to weld the perimeter of the boxes. They are reinforced at all weld points to ensure that the boxes essentially become one with the chassis.
A shock mount on each side was needed to, well, mount the shocks. So, our team made them and welded them in. On this particular application, we were planning on a very low ride height, so we also cut out the stock spring boxes, stock shock mounts, and trimmed the frame rail, to install mini-tubs. The frame rails were also notched for proper axle clearance, which is commonly done so that the rear never comes into contact with the frame rails. These modifications are necessary to allow the suspension to be adjusted correctly at any ride height, without any clearance issues.
With the installation complete, the team can move forward with the rest of the suspension work, and Project Evil is well on its way to its next launch.