oxfordgt

This is my “everything I have learned about the mustang suspension” thread. I have recently completely changed out all of my suspension components. Before I started ordering parts I did my research. I just thought that I would share all of what I have learned with you guys so you won’t have to search like I did.

FRONT SUSPENSION
The 1979-2004 Mustang front suspension consists of modified MacPherson struts with lower control arms (A-arms). The term modified refers to the fact that the coil springs are inboard of the struts. Normally, MacPherson suspensions have coil springs that surround the struts. This suspension is compact, cheap to build and easy to service, but it is often criticized because (a) its geometry produces camber changes during vertical suspension movement and body roll that adversely affect handling and (b) the strut towers prevent designers from lowering the car's profile. The performance of the front suspension can be improved by installing stiffer springs and struts and by replacing rubber bushings in several locations with less compliant urethane bushings.
LOWERING
Before a car is lowered, its front control arms were parallel to the ground. Lowering the ride height by changing the springs causes the control arms to angle upward. This has a negative effect on front suspension performance. It lowers the front rollcenter, which increases the car's natural tendancy to understeer. It reduces the range of strut and control arm compression travel. It changes the alignment of the sway bar with the lower control arm. And it changes the alignment of the tie rod with the lower control arm. If the car is lowered much more than 1.5", this misalignment may produce, bumpsteer which occurs when the tie rod pulls the steering arm left or right as you go over a bump.
The steering geometry can be restored on severely dropped cars by installing a bumpsteer kit that lowers the tie-rod ends slightly relative to the spindle, or by raising the steering rack with offset rack bushings. Sway bar misalignment can be corrected by installing shorter sway bar end links. The roll center can be raised back up by installing taller ball joints.
An alternative that accomodates both lowering springs and fine tuning of the Mustang's front end geometry is to replace the K-member and control arms with aftermarket units. Typically, these units have mounting points that can be changed to provide for correct control arm alignment at different ride heights. They are also lighter weight than the stock units, provide for an increase in wheelbase, and improve the steering geometry. Some of these aftermarket units can be used with springs in the stock position but most require a coil over set up.
SWAY BARS
Front and rear sway bars or anti-roll bars are designed to reduce body-roll during turns. They have no influence on the suspension when wheels bounce in unison. They only come into play when they are twisted, that is, when vertical movement on one side of the bar exceeds the vertical movement on the other side, as when the body rolls or only one wheel goes over a bump. In addition to reducing body-roll, sway bars also reduce the adhesion limits of the side-by-side wheels that are being acted upon. This allows sway bars to be used as suspension tuning devices. By varying the stiffness of the front and rear sway bars you can influence the oversteering or understeering characteristics of a car.
Firms such as Steeda and Maximum Motorsports sell adjustable rear sway bars that make this suspension tuning a simple operation. The Steeda bar is an add-on to the stock sway bar. The Maximum Motorsports unit replaces the stock rear sway bar.
You should use moderation if you decide to upgrade your Mustang's existing sway bars. If too stiff a sway bar is installed on either axle, it can cause the inside wheel to lift completely off the ground in hard turns. And if the rear sway bar is made too stiff relative to the front bar, it can produce oversteer and dangerous handling. As general rules of thumb, on a street-driven Mustang it is best to (1) stick with sway bars that are close to the stock sizes produced by Ford and (2) don't install a rear sway bar that is thicker/stiffer than the front sway bar.
SPRINGS, SHOCKS AND STRUTS
The coil springs in a Mustang's suspension can be replaced with aftermarket springs that lower the car and/or increase the stiffness of the suspension. When that is done, it may also be necessary to replace the shocks and struts with stiffer units that match the stiffness of the new springs. The purpose of shocks/struts is to dampen the oscillations of the springs after the car travels over a bump or dip. Ideally, the oscillation will be limited to just one cycle. If the shock/struts are too soft in relation to the springs, the oscillations will continue for more than one cycle and the car will bounce repeatedly. If they are too stiff, the spring will not be able to complete a full cycle and the tires will not be able to follow changes in the road surface. Either situation will have a negative effect on traction, handling, and ride quality.
You can also replace the stock springs with coilover springs which are mounted on the front struts and the rear shocks. Coilovers have a mechanical advantage over the stock springs because they are located farther out on the control arm; and for that reason, they are smaller and lighter than stock springs with the same effective wheel rate. The more efficient coilover springs permit the use of very high wheel rates to reduce body roll and brake dive without hurting ride quality. Coilovers also feature threaded collars on the shocks/struts that permit easy adjustment of ride height - a useful feature on a competition car.
CHASSIS
The Mustang's chassis is constructed of sheet metal which is formed into channels and box sections to give it strength. The suspension components are bolted to sheet metal subframes at the front and rear of the car. The rocker panels form a box section on each side to provide longitudinal rigidity. This produces a strong, lightweight chassis, but one that has a tendency to flex. It is sometimes referred to as the 5th spring in the Mustang's suspension. Chassis stiffness can be improved by installing subframe connectors and a strut tower brace.
REAR SUSPENSION
The 1979-2004 Mustang's 4-link rear suspension consists of a live rear axle held in position by upper and lower control arms, coil springs, and gas-filled shock absorbers. It includes an 8.8" traction lock rear, quad shocks (shocks & dampers), and a rear sway bar. The upper and lower rear control arms constitute the four links in this rear suspension. The upper arms locate the axle side-to-side and prevent pinion angle changes (axle wind-up). The lower arms locate the axle front-to-back and and transmit the wheels' thrust to the chassis. Note that the control arms are not parallel to each other.
When the car leans (rolls) in a turn, one side of the chassis moves upward relative to the rear axle, the other side moves downward, and these non-parallel control arms must twist and change length axially to allow the axle to articulate. This causes the control arm bushings to bind. If this bind becomes excessive, it can raise the rear wheel rate and produce sudden, undesireable changes in handling (e.g., snap oversteer).
Ford minimizes this suspension bind by using compliant rubber bushings in both the upper and lower control arms. These relatively "soft" bushings acommodate the necessary motion of the control arms during body roll. However, they also permit wheel hop on hard launches and horizontal axle deflection in aggressive turns. Axle dampers (quad shocks) were installed on V8 Mustangs to eliminate this wheel hop, but nothing was done by Ford to cure the horizontal axle deflection. That deflection i

Triisomy21

Code, seriously, we need a tech section. In the past week or so we've had three really good threads like this.[sm=goodidea.gif]

Suspension
Backpressure
Gears

Come on man, pull some strings

4.698GT

There is a sticky that is all tech, take a look

oxfordgt

I really wish we could get a tech and a how to. I wrote one on gears a couple of days ago and this one. The one on gears is already a few pages back[:@].

I have more info on suspension about alignment and various other suspension components but I didn't want to make this to long.

I think the next one is going to be exhaust.

Yeah I have to much time on my hands.

Triisomy21

Too much time? Nah, you're learning and being helpful to others.

Triisomy21

Good call. Can we get our stuff in there?

A double post? Shoot son!

FRunner

Nice work, thanks for taking the time.

dothack

real good info

oxfordgt

Thanks guys making these threads is more fun then anything and it kills about an hour of my day.

Fryguy22

very informative write-up. Thanks a bunch