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Suspension 101 Part 2: Mustang Bracing & Chassis Strength

Written By: Andrew Cilio

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Strengthening your mustang's chassis, especially for older model Mustangs, is essential if you want all of your motor's power put to use. A car that flexes under load or rolls through turns is loosing tame and power.

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When one thinks of suspension mods for Mustangs, shocks and springs first come to mind. One area that's usually neglected is the chassis itself.

American Muscle

The Mustang Uni-Body Chassis

The Mustang uses a chassis with two main components, the front and rear subframe. While the two sections are connected by the floor pan, this is nothing more than sheet metal. The actual frame rails are not connected. While the rest of the car's body provides some rigidity, there can be unwanted flex when the chassis of the car is stressed. This stress can be a result of hard cornering or dragstrip launches. The solution for this is simple, and can be found in the form of subframe connectors, which will tie the front and rear subframes together, thus stiffening the chassis.

  • Bolt-on subframe connectors offer easier installation
  • Welded connectors provide more stiffness than bolt-ons
  • Strut tower braces also help reduce body flex in a different way than subframe connectors
  • Some strut braces have the clearance for supercharger engines
  • Rear shock braces are a minor upgrade, but stilll reduce flex. Usually requires welding
  • Torque box braces dampen the force of hard launches
  • A full roll cage offers the most riggidty. Depending on your end goals, this might also be the best option
2014 Mustang GT Launching on the Drag Strip

Bolt-On Subframe Connectors

Bolt-on subframe connectors are the easiest to install. They simply bolt into place between the frame rails, although some connectors may require additional holes to be drilled. Once installed, the connectors connect the front and rear subframes into a single cohesive unit. For additional strength, you can additionally weld the bolt-on subframe connectors as well, strengthening them even further. Over time, the bolts can loosen or even shift their hold, as the car's subframes try to twist apart from one another. Welding helps to prevent this.

Bolt-On Subframe Connectors

Welded Subframe Connectors

The best options, when it comes to subframe connectors, are ones that weld into place. These subframe connectors offer improved strength, because they do not rely on bolts to secure them to the front and rear subframes. Since the average person doesn't have the capability of welding them in their garage, installation will likely involve a trip to a shop that will weld them into place for you.

Weld-In Subframe Connectors

Special Information Package Regarding Convertibles

Due to the lack of a true roof in a convertible, the uni-body chassis is weaker than it would be with a coupe. So for most year models of the Mustang, Ford equipped them with subframe connectors from the factory. These subframe connectors are bolted into place, and helped make up for the lack of the roof's ability to help strengthen the chassis frame.

1999-2004 Mustang GT Convertible

Strut Tower Braces

The front strut/shock towers are another point on the Mustang chassis that can benefit from some additional strengthening. These towers serve as the mounting point for the struts, and therefore they are the recipients of a great deal of stress. In fact, with the proper tools, you can even measure small changes in the relationship of the shock towers to one another when the vehicle is jacked up as opposed to resting on the ground. Knowing that, one can easily see why hard cornering could cause chassis flex in this area.

To combat this, you can install a brace that will tie the two towers to one another. This reduces flex, thanks to the tubular or bar-shaped section that's used for the main body of the brace. Different connectors may use either two, or four of the bolts on each shock tower. The use of all four bolts provides more rigidity, but visiting the alignment shop afterwards is a good idea, as removing all four bolts for installation can alter your vehicle's alignment.

Mustang GT Strut Tower Brace

Special Information for Those with Positive Displacement Superchargers, or Aftermarket Intakes

There are a multitude of shock/strut braces on the market. If you're trying to clear more than just the engine, however, the selection will narrow somewhat, and choosing the proper one is much more critical. So, while the following suggestions are not your only options, they may help if you're looking at purchasing a strut tower brace.

  • 1999-2004 Mustang: Steeda Strut Tower Brace (American Muscle Part # 16107)
  • 2003-2004 Mustang Cobra: Agent 47 Strut Tower Brace (American Muscle Part # 30201)
  • 2005 Mustang: Agent 47 Double Barrel Max Clearance Strut Tower Brace (American Muscle Part # 30200)
Mustang GT with a Strut Tower Brace and an SVT Supercharger

Mustang Rear Shock Braces

Just like the front strut tower brace, a rear shock tower brace can reduce unwanted flex as well. The rear shock towers are generally not under as much stress as the front, but if you're looking to continue strengthening your Mustangs chassis, a rear shock tower brace will certainly do it. There are fewer options for rear shock tower braces, but still plenty to choose from. Most rear shock tower braces will also require some welding as well, which makes installation a little more complicated than a simple bolt-on affair.

Mustang Rear Shock Tower Brace

Mustang Torque Box Braces

Connecting the subframes of the Mustang with subframe connectors aren't going to address all the weak spots in the chassis. While it will help, there's still another crucial area to address for drag racers launching at higher RPM's. That area is the rear torque boxes. This area catches the brunt of a hard launch, receiving a lot of stress from the axle, especially if the rest of the chassis is stiffened up already.

There are several options to choose from in regards to torque box braces. Some are smaller braces that weld in place, while others are larger and can tie the torque box area into the frame rail. You can choose between bolt-on options and those that are intended to be welded. As with the subframe connectors, welding the braces will yield an advantage when it comes to strength.

2003 Mustang Cobra on a Drag Strip

Mustang Roll Bar/Roll Cage

If you want to look into the ultimate way to stiffen up your Mustang, as well as provide a safer place for the driver, look towards a roll bar or roll cage. You can get a simple 4 point bar for the rear of the Mustang, or elect to get a full cage to offer substantial protection and chassis stiffening. As with many other suspension components, you can get roll cages that bolt in place, or that require welding. Depending upon how fast your car is, some tracks may require a certain type of roll bar or roll cage. So if you have dragstrip goals in mind, plan ahead. It's easier to do it right the first time, than to do it multiple times. Note that for convertibles, a light bar does not fall into this category. It is merely a cosmetic feature.

Mustang Roll Cage

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