Suspension

Springs

Many people who own Mustangs know about the apparent “4 x 4” look. Ford, for some reason, designed these cars with large gaps in the wheel wells. A common modification is to add lowering springs to help lower that gap and make the car look more appealing. The most common lowering springs are made by H&R and Eibach Spring rates are rated by lbs/in. The higher the spring rate, the stiffer the ride will be and the better the handling. Once you start going to higher spring rates, you want to get a shock and strut that will balance the spring. Too high of a rate will disable the shock’s and strut’s ability to dampen the spring, and leave you with a negating effect. When lowering a Mustang, the geometry will change which might requite the use of Caster/Camber plates to re-align the wheels. The rule of thumb is lowering the car by 1.5’’+ is when you need Caster/Camber plates; however, that is not an exact science. By not adding Caster/Camber plates, your tire wear will be uneven and the car will not handle as well as it did before you lowered it. If you’re really tight on cash, you can get Steeda’s cam bolts which can help align your car properly for 1/10^th the cost of caster/camber plates. The problem is they place a lot of stress on the strut and are just too hard on them during a coilover setup. Also, you won’t have as much adjustability as you do with caster/camber plates. Eibach is known to have sagging issues with their springs. I recommend H&R springs. Anything below 1.6''s will also mess up the Mustang's suspension geometry for those who are interested in open tracking as well. For spring rates on various springs, go here.

For installation instructions, go here: http://www.mustangworld.com/ourpics/fcar/steedaspring1.htm

Coilovers

Coilovers were thought to be a race only item way back when. Today, companies such as Maximum Motorsports have made them streetable and road friendly. Coilovers are springs that go directly over the shock or strut. By putting them directly on the shock or strut, you not only allow for complete height adjustability at a twist of a wrench but also enable less strain on the lower control arms and less bind in the rear. To convert to coilovers, you must first buy a kit from Maximum Motorsprots, X2C Motorsports or various other companies. Adjustability is a snap with coilovers. All you need is a spanner wrench for Maximum Motorsports’ kit (can be purchased at $9.95). Although converting to coilovers is not cheap, it offers adjustability, reduces bind and allows for an easier change of springs. Expect to pay around $1500 for a complete kit including shocks, struts and your choice of springs. One thing you may notice is that spring rates are much smaller than the rates of normal coil springs. Consult the company on what spring rate would be right for you. You will also need to purchase a set of coilover compatible Caster/Camber plates. For a better explanation, go here. Maximum Motorsports and Griggs make the best kits out there. The others are decent but are light years away from coming close to the quality and superiority both MM and Griggs have.

Shocks and Struts

Shocks and struts provide opposing force for the springs. Without shocks and struts, the car would just bounce constantly. Shocks and struts prevent this, as well as preventing you from bottoming out when you run over a pothole. They are many different kinds of shocks and struts; which one for you depends on what you want to do with your car. Bilstein, Koni and Tokico are three of the leading manufacturers in performance shocks and struts for the mustang. Struts are basically shocks that do more than one job. They perform the following:

Wheel and axle control together with transverse links

Absorbs coil spring forces via a spring cap (McPherson solution)

Supports braking torque

Absorption or transmission of wheel control movements

Supports stabilizer mounts

Support of sensor and/or cable mounts

Struts are found up front (under and connected to the strut tower braces) and shocks are found in the back.

For those who are into drag racing, you'll want maximum transfer to the rear wheels. For a daily driver who wants at least some handling, 70/30s will work well. For those who are more 1/4 mile oriented, 90/10s are the only choice for struts. The stock shocks are fine for drag racing as they're already 50/50.

For installation instructions, go here: http://www.corral.net/projects/subzero/tokico.html

4 Link Suspension Control Arms, Problems and Bushings

The Mustang’s rear suspension is known as a 4 link suspension. It consists of two upper control arms and two lower control arms to hold the live axle in place. The upper control arms prevent axle side-to-side movement and axle wind up while the lower control arms prevent front-to-back movement.

Problems Faced With the 4 Link

The Mustang’s suspension is not designed well. When there is body roll due to turning, one side of the chassis moves upwards while the other moves downward. The control arms twist to allow the axle to move during turning and cause bind. If the bind is too much for the rear end to handle, the car will exhibit a snap oversteer – not good. Ford uses rubber bushings to allow for the axles to move a bit during turns. Bind is not as apparent with rubber bushings but it is by no means gone. Soft bushings such as rubber can produce wheel hop and “fish tailing.”

Ways to Fix the 4 Link

Today’s technology allows for a few possibilities to change the 4 link suspension. One way is to get after market control arms. Another is to use a torque arm and an axle-locating device. The final way is to convert the rear suspension to a 3 link or 5 link suspension system.

Lower Control Arms

There are many lower control arms on today’s market that help the Mustang. By switching to stronger or adjustable lower control arms, you can gain weight transfer to the rear, allow for taller slicks and reduce binding in the rear. The best manufacturers of lower control arms are Maximum Motorsports, Griggs, Pro3i and Steeda.

Bushings in Control Arms

Many companies are starting to have a polyurethane and spherical bushing craze. Companies are stating that polyurethane and spherical will improve your ET, reduce axle deflection and improve grip. This is true, however, due to the hardness of the bushings, they produce major bind issues during body roll as the bushings cannot allow for the necessary movement of the control arms. Because of this, polyurethane and spherical bushings should only be used for dragstrip cars.

Maximum Motorsports did a project on spherical bushings by creating a 1/5 scale model of the 4 link. They found that although the bushings themselves did reduce binding in the control arms, there were other unexplained problems with the tie rod ends. Some people argue that when you have all four tie rod ends, you hinder the kinematics during body roll and the axle moves in an undesirable and unpredictable way. Maximum Motorsports later proposed that the results were un-conclusive though because there were too many “real world” factors that could not be accounted for. Cliff Notes: Unless you are a drag racer or have a high HP car, steer clear of polyurethane bushings in both control arm ends.

Torque Arm

Torque arms have been around for quite awhile. The 4-link suspension is a great design…if you’re a drag racer. With the stock 4-link suspension, the upper control arms are supposed to locate horizontal axle movement and control axle wind-up. The thing is, the stock uppers are awful at doing both jobs. The job of a torque arm is to break the upper control arm’s jobs in pieces. The torque arm controls axle wind-up and does it very well. When switching to a torque arm, you must switch to a panhard bar as well. Without a panhard bar, the axle would move horizontally out of control. After you switch to a torque arm and panhard bar or watts link, go ahead and throw the upper control arms in the trash; they are not needed anymore. The main companies that offer torque arms for the mustang platform are Maximum Motorsports and Griggs.

Panhard Bar

A panhard bar, usually used in conjunction with a torque arm, controls side-to-side horizontal axle movement. F-Bodys have been using them for years with their 3-link system. Some even allow you to adjust the roll center height to allow further tune ability of your car. When observing a panhard bar’s full degree of movement, you will notice it will have a slight hyperbolic arc. This is because only one side is actually locating the device; it’s the nature of the beast.

Watts Link

A watts link does the same thing a panhard bar does, but more preceisly. Watts links are either connected to the differential cover or to the chassis itself. Unlike the panhard bar, it has no hyperbolic arc at all. Some watts links allow you to adjust the roll center. A few problems occur whenever you add any of these rear suspension devices though. Exhaust might not clear the items that will require you to custom fabricate something to work. Your rear grip will be so extreme now, that you’ll have massive understeer too. To cure the understeer problem, an adjustable rear swaybar can help, as well as a new K-member.

Sway Bars

Sway bars, sta-bars or stabilizer bars help prevent major body lean from occurring during turn-in. Here is a quick snippet taken from “How Stuff Works.”

“Stabilizer bars are part of a car's suspension system. They are sometimes also called anti-sway bars or anti-roll bars. Their purpose in life is to try to keep the car's body from "rolling" in a sharp turn.

Think about what happens to a car in a sharp turn. If you are inside the car, you know that your body gets pulled toward the outside of the turn. The same thing is happening to all the parts of the car. So the part of the car on the outside of the turn gets pushed down toward the road and the part of the car on the inside of the turn rises up. In other words, the body of the car "rolls" 10 or 20 or 30 degrees toward the outside of the turn. If you take a turn fast enough, the tires on the inside of the turn actually rise off the road and the car flips over.

Roll is bad. It tends to put more weight on the outside tires and less weigh on the inside tires, reducing traction. It also messes up steering. What you would like is for the body of the car to remain flat through a turn so that the weight stays distributed evenly on all four tires.

A stabilizer bar tries to keep the car's body flat by moving force from one side of the body to another. To picture how a stabilizer bar works, imagine a metal rod that is an inch or two (2 to 5 cm) in diameter. If your front tires are 5 feet (1.6 meters) apart, make the rod about 4 feet long. Attach the rod to the frame of the car in front of the front tires, but attach it with bushings in such a way that it can rotate. Now attach arms from the rod to the front suspension member on both sides.

When you go into a turn now, the front suspension member of the outside of the turn gets pushed upward. The arm of the sway bar gets pushed upward, and this applies torsion to the rod. The torsion them moves the arm at the other end of the rod, and this causes the suspension on the other side of the car to compress as well. The car's body tends to stay flat in the turn.

If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.”

Now that that’s out of the way, upgrading your sway bar is a wonderful way to fix that massive understeer that occurs when switching to a torque arm/panhard bar setup but not the best thing done to a stock car. Adjustable sway bars allow for dialing in understeer or oversteer. By having an adjustable sway bar, you can set up your car exactly to track specific conditions. Drag racers can also benefit as MM makes one for you specifically. For those of you who have a torque arm and panhard bar, a sway bar would be great for those who don’t want to buy a k-member.

For installation instructions, go here: http://www.mustangworld.com/ourpics/fcar/dansway.htm

Related Link, for additional/supplemental information, a MUST READ if you own a Mustang: http://www.miracerros.com/mustang/t_suspension.htm