One of the great things about the Mustang is that it’s a unibody/subframe car. However, one of the not-so-great things about the Mustang is that it’s a unibody/subframe car. The unibody construction makes building the car easier. It also makes the car lighter. However, a car with a subframe gets its stiffness from the rockers and floorpan. The problem here is that, especially with older cars, these aren’t as stiff as the engineers intended them to be. That’s where subframe connectors come into play.

The Maximum Motorsports Subframe Connector kit for 1979-2004 Mustangs comes with everything shown here.

What Do Subframe Connectors Do?

In short, subframe connectors connect the front and rear subframe sections. In effect, they create a single frame-rail from the front to rear. This eliminates the vast majority of body flex inherent in the unibody design. A car body that flexes diminishes the effectiveness of all the money and time you spent upgrading the suspension components. Shocks and springs are only able to work properly with a stiffer chassis.

This shows how subframe connectors connect the front and rear subframe sections.

How do they do this, you might ask? They accomplish it by connecting the front and rear frame rails. They are the same width as the front and rear frame rails. However, being in the area of 65 inches long for a Fox or SN-95 Mustang, subframe connectors, in some cases, overlap the front and rear rails by about six inches.

The best ones are welded to the subframes and also have tabs that rest along the outer side of the rail. The tabs are welded to the sides of the rails and any gaps in front of the tabs between frame rails and the connectors are filled in by welding. The setup we are showing here from Maximum Motorsports, also contains seat braces to add more stability to the car and most others don’t have these braces.

Two Kinds of Subframe Connectors

You can see here how the front tabs are welded.

You can probably guess that these two types are bolt-in and welded connectors. Obviously, the bolt-in kind is easier to install. However, the welded ones are stronger and welding provides a better connection between the stiffeners and the frame rails. You may think that since you don’t know how to weld (very well), you have to install the bolt-in kind. That’s not true.

Your welds don’t have to be perfect and beautiful, so you can run an ugly (but functional) bead, and then grind the bead down with a cut-off wheel to clean it up. If you would like, you can spend a few bucks on some scrap material and an hour or so practicing on it. The key is proper metal prep prior to welding. There can’t be any rust, paint, or other contaminants on the metal where you’re welding. This is where a good wire brush or a soft grinding wheel on your drill comes into play.

Maximum Motorsports Subframe Connectors

The Maximum Motorsports Mustang Subframe Connector kit installed and painted to keep it from rusting.

Maximum Motorsports certainly makes top-quality, late-model Mustang subframe connectors. They are very effective, because they reach from just under the firewall/bulkhead all the way back to just in front of the lower control arm attachment point. Among the stiffest Mustang subframe connectors on the market, another significant feature is that they don’t hang down below the exhaust when properly installed, which is definitely something to consider for Mustangs with a lower-than-stock ride height.