Suspension Upgrades to Improve your Foxbody Mustang's Handling

There are many reasons to upgrade. Some people would like their Mustang to be a drag king. Others prefer an auto-cross master (track racing). Many Mustang enthusiasts just want an improved ride over the stock components. All of these situations are entirely feasible and use different suspension components to attain the desired result. To get the ball rolling, we'll start with over viewing a basic suspension upgrade to restore ride quality to your Mustang. From there we can motor on to more complicated and performance enhancing applications.

Now upgrading your suspension is not going to make your motor produce more horsepower or torque. However, an upgraded suspension and chassis will make your Fox faster by better manipulating the power and torque that is available. Better acceleration times, better power and weight transfer, decreased braking distances, increased cornering speeds - these are all benefits of upgrading the stock suspension components. Again, no power gains, but if you are now able to maintain 60 MPH through a corner versus 40 MPH, you'll reach the finish line faster. Ways to improve handling include:

• Replacing the stock struts and springs for lowering springs and better performing struts
• Coil over setups forgo the strut and spring combo for one track ready unit
• Tubular front control arms and stabilizer bar end-links with polyurethane bushings help steering response
• Aftermarket rear control arms eliminate annoying wheel hop issues with the stock parts
• Caster camber plates allow for alignment adjustments to maximize the contact patch of your tire with the pavement
• Bumpsteer kits help keep your tires planted and restore proper suspension geometry 
• K-members offer weight savings and more chassis rigidity

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Up front, Foxbody Mustangs came equipped with stamped-steel, A-shaped lower control arms, and a modified MacPherson strut. This is a very common and widely-used design due to the simplicity of it. However, this simplicity also leaves out some performance. Foxs exhibit skittish behavior under hard cornering and limited camber adjustment leads to less than optimal tracking.

The rear end of a Mustang is an entirely different story. Continuing the use of their 'famed' live rear axle, the rear suspension is of a very primitive design and is prone to wheel hop under hard acceleration and binding in tight turns. Rectifying these problems isn't too hard, and once done will completely change the way your pony feels and drives at any speed.

As mentioned, some Mustang owners are just seeking to restore the ride quality of their Mustang. Over the years, wear and tear, use and abuse will take its toll on the stock suspension components. As such, performance, handling and even braking will suffer. Replacing the worn components with today's modern counterparts is a sure fire way to improve handling, ride characteristics, poise and perhaps most importantly, safety of the car. Let's also consider what's available in terms of retaining the stock strut and coil setup. There are three main suspension components to examine:

• Struts -  adjustable struts such as Koni, Bilstein, and Eibach are a major upgrade over the stock unit
• Coil springs - stiffer springs, tighter handling
• End-links - brand new links rejuvenates handling

What are these end-links? They attach the stabilizer bar to the lower control arm, one on each side. Often overlooked, these simple components can play a big role in handling and overall feel over the car. Over time, the stock bushings wear and the links themselves can even break. Replacing these with a simple OE replacement kit is highly recommended. If you’re looking for a slighter stiffer, better performing ride, opt for a kit with polyurethane bushings.

Replacing the Big Three (struts, coil springs and end-links), using any of the parts listed, is guaranteed to give your Foxbody a whole new ride – even if you have selected simple OE replacement components. Replacing your stock components for modern equivalents will make a capable road machine; fun to drive but uncompromising in comfort. If you’re looking to go one step further and take your road warrior to a track monster, continue reading.

The world of struts has come a long way since the implementation of those barbaric struts installed back in the 80’s. Offerings from Bilstein, Lakewood, and KYB are widely popular replacement struts and range from an economical basic strut to an all-out road warrior piece. Replacing stock struts with more performance-orientated, adjustable units will lead to great results, but still be comfortable on the street. You can also replace the stock coil springs to match the struts, and use different lengths to either raise or lower the car. Most choose shorter coil springs for lowering and give their Mustang a more aggressive look. Make sure to properly match the coil spring with the strut and the weight of your vehicle.

Lakewood: Lakewood is largely known in amongst the drag racing pool, but they too have developed a mild street/strip strut for the Foxbody. Lakewood has engineered a nice blend of performance without sacrificing comfort or poise with their 70/30 labeled struts.

Bilstein: These bad boys are heavy hitters. They’ll cost you more, but accompanying that price tag comes undisputed performance, recognition, and popularity amongst the aftermarket Mustang crowd. Bilstein HD’s (Heavy Duty), of all the struts listed, are the most orientated to vehicle handling and performance. Due to this, their ride can be stiffer compared to the other struts. However, if you’re looking to carve corners like your car is on rails, you can’t go wrong with Bilstein HD’s. Among stock geometry suspension setups, Bilstein HD’s are among the highest performing.

When buying and installing new struts it is strongly recommended to replace the mounting hardware as well. MOOG provides a quality front strut assembly mounting kit with all the necessary components to get the job done right.

Lakewood and Bilstein also offer rear shocks to compliment your upgraded front end. Both will increase vehicle traction as well as weight and power transfer. Expect the ride to be a little stiffer than standard absorbers but by no means at all uncomfortable. In fact, a gain in comfort over stock should be noticeable!

Bilstein quad-shock is certainly something to consider. First off, what are they? Well, in 1984, Ford introduced the quad-shock, a horizontally orientated shock absorber connected at one end to the upper frame and at the other end to the main shock absorber bracket. The purpose of it was to control wheel hop which is most prominent under hard acceleration (wheel hop is actually the wheel/axle system bouncing up and down very quickly due to torsional forces from a hard launch. Imagine driving over continuous rail-road crossings.). Replacing the worn quad shocks are a good preventative measure that wheel hop will always remain under control. Wheel hop gone bad (the next hit series alongside ‘girls gone wild’) can result in severe damage to the rear end of the car. The number one benefit of new quad shocks will be increased traction.

Another option is QA1 shocks. They offer a high-performance, adjustable rear shock absorber to really wring out every last ounce of performance to be had from the stock suspension geometry. The full adjustability allows you as the driver to modify the absorber response and handling to your liking. Furthermore, like the others, they require no modification to install.

As mentioned above a lowered stance gives your pony a more aggressive look and closes the gap between tire and fender for a cleaner appearance. The most important aspect regarding lowering is the decreased center of gravity. A lower center of gravity makes the car feel more planted and increases your handling ability.

A new set of springs can enhance performance as well, particularly if the previous springs were originals. There are many different lengths and spring rates. It's best to pick a spring to match your shock. A mismatched spring and shock combination will adversely affect handling, causing the car to bounce after hitting a bump, bottoming out prematurely, and ultimately causing more wear on the car as a whole. Also consider different style Foxes (coupe, hatchback) use springs with different rates and capacities due to weight and distribution differences amongst the different body styles.

Coil overs, particularly in the rear, are best suited to Fox Body Mustangs destined for track use. When installed in the back end of a Fox Body, they are not known for great street manners (coil overs in the front are not as bad) as they are for their proven track ability. A good coil over kit essentially rectifies all the weak points originally found in the stock suspension architecture. Coil overs are certainly more costly than standard strut/shock replacement, but their distinct performance advantages certainly make them a must for any Foxbody owner wishing to squeeze every last bit of performance out of their Mustang.

Many aftermarket kits come complete with everything necessary to upgrade to a modern coil over architecture. Mounting hardware, 12-way adjustable shocks, and springs rated at 150 lbs are one example of a suspension package designed to maximize traction both at launch, for the drag guys, and to maximize grip while cornering for the autocross crowd. Coil over kits are definitely the most expensive rear suspension upgrade (they require aftermarket control arms as well), but for the Mustang owners who are really serious about racing, they are the way to go, Hands down.

Eibach’s Pro-Street coil over kit is a stupendous way to maximize your Foxbody’s cornering behavior. An estimated, average Joe afternoon install time later and these coils will have your pony carving through the curves. The coil overs are designed for maximum track AND street performance with full adjustability. This way you can drive the car to the track, make a few quick adjustments, thrash around at high speeds for a while, and then saunter back home without causing your delicate derriere any unnecessary pain. Performance wise, better turn in response, improved handling, and increased cornering grip can all be expected when running the Pro Street kit. These springs will lower the car between 1” to 2.5” depending on how they have been adjusted.

Changing the stock control arms with an aftermarket tubular type will stiffen up your Mustang, shed some weight, and increase handling and tracking as well as reduce binding due to better geometry. Even better, new control arms have new bushings (usually stiffer, polyurethane bushings) and potentially new ball joints as well which will definitely improve steering response. Aftermarket arms have also been engineered to deal with wheel hop. This means you won't need quad shocks, and subsequently you'll be able to fit bigger wheels and tires under your Mustang.

Overall, you'll experience better power transfer during straight line launches, and you'll maintain grip in hard corners because of better contact with the road. Add in a coil over kit like mentioned above, and your Foxbody Mustang will be at its peak performance, handling wise. It's impossible to take a live rear axle and have it operate like a modern independent suspension system. However, a good combination of control arms and coil overs will yield the closest thing possible to a modern IRS while maximizing your Fox’s ability to keep its tires planted in all driving conditions.

QA1 control arms are a great choice when adding a coil-over setup to your ‘Stang. They offer greater strength over the stockers and have been engineered to optimize performance with coil-overs (you can see they lack the spring perch found on regular control arms). Furthermore, not only are these pieces stronger, they are also lighter. A bonus power-to-weight gain to boot! The main advantages of these pieces are to work in harmony with the coil-overs and to properly secure them in their correct position to enhance the handling characteristics of the vehicle. They're also fully adjustable while installed on your Mustang!

J&M employs a patented 3-piece ‘Poly ball’ bushing designed for hard launches and power transfer, but yet retain compressibility to maintain tire-to-ground contact in the corners.

Steeda Autosport has adjustable arms which can be tweaked while on the car to alter the pinion angle and optimize traction for any given condition (much like the QA1 arms). Included are Steeda’s 3-part bushing, designed to maximize traction but retain stock comfort levels.

BBK control arms come as a complete package, both upper and lower. Utilizing polyurethane bushings and precision welding, BBK control arms are a bargain. As a bonus, they come finished in a durable black powder coat.

Maximum Motorsports are on the expensive end, but excellent design and implementation have made them and industry leader in aftermarket suspension parts. The proper bushings on each end of the arm insure maximum performance in all conditions, without sacrificing ride quality.

If you're building a corner carving Foxbody, caster camber plates are a must have. Some coil over kits require the use of said plates because of the change in geometry from lowering the car. In fact, even if you prefer to run a stock Fox over a turn-eating behemoth, caster camber plates are still highly recommended.

A major problem with the Foxbody Mustang generation is they came out of the factory with very limited ability to adjust wheel camber and no ability at all to adjust wheel caster. The stock slotted plates atop the front strut towers do not offer enough camber adjustment to prevent the front tires from pointing in towards each other as the car and its components age. The lack of caster provisions prevent the wheels from remaining level when the suspension is under turning loads, thus inducing further tire wear. The solution to this is, like always, available through the Mustang aftermarket. Maximum Motorsports, SR Performance, QA1, and Hotchkis all offer precision-engineered pieces to repair this problem. Using caster camber plates guarantees proper front-end alignment for your car.

Another issue when modifying your suspension is bumpsteer. Bumpsteer occurs when there is a geometry mismatch between the outer tie-rod end and steering rack (typically occurs with lowered vehicles). Essentially what happens is due to this mismatch of angles, when the car hits a bump, the tire will move in an extended arc and may lose contact with the road. When the tire loses contact with the road, it will turn in the direction in which the last force acted upon it. Thus the wheels turn involuntarily and the driver momentarily loses control. Steeda has devised an effective and easy-to-install bumpsteer kit to restore proper geometry within the steering and suspension components. This too is a necessary piece when installing aftermarket coil-over sets. The coil-overs will change the geometry such that bumpsteer will be prevalent.

Depending on how serious you are with racing and what your coil-over kit specifies, a new replacement K-member may be on the list to get. QA1 again comes up with a perfect solution, presenting us with their tubular K-member. It is manufactured to bolt right in with no hassle or modification. Like the control arms, added benefits are lighter weight and greater torsional strength.

It's impossible to take a live rear axle and have it operate like a modern independent suspension system. However, a good combination of control arms, coil overs, and other modifications will yield the closest thing possible to a modern IRS and maximizing the Fox’s ability to plant the rear tires in all driving conditions.

The most important thing before you start modifying your Mustang is to keep your end goal in mind. A autocross Mustang setup will look quite different than a dragster, and the dragster will look completely different than a daily driven, street machine.