Worn Out Shocks & Struts Affect More Than Your Comfort!

Excess vibration and movement due to worn shocks and struts may cause unnecessary and accelerated wear on other suspension components, brakes, and tires.

Suspension Questions & Answers

These are some of the common questions that are likely to indicate a problem with your suspension system:

Understanding Your Suspension

Shock Absorbers

Shock absorbers are used to return the suspension to its natural position quickly and smoothly, thus giving you a soft ride over soft bumps and firm control over spring action for cushioning large bumps. Not only do shock absorbers control the compression of the spring, but the expansion (or rebound) as well.

Shock absorbers control the movement of the springs by using fluid or gas that is forced through openings in the pistons and valves. The size of the holes will determine the dampening effect of the shock.

As a shock absorber compresses or expands, a piston inside moves through oil or hydraulic fluid. The piston's movement is resisted by the fluid, which must pass through the small holes. When the holes are made smaller, the shock absorber becomes stiffer, delivering a sportier ride with firmer handling characteristics.

Fluid flow through the pistons is controlled by spring loaded valves. Hydraulic shock absorbers automatically adapt to the severity of the shock. If the axle moves slowly, resistance to the flow of fluid will be light. If the axle movement is rapid or violent, the resistance is stronger (since more time is required to force the fluid through the openings).

Another method used to deliver sportier handling performance is to use a chamber filled with pressurized gas, such as nitrogen, above the fluid in the shock absorber. The gas helps the dampening action as it compresses and expands. Gas pressurized shocks react more progressively to bumps.

Air shocks have an internal air chamber provided so that vehicle curb height ban be kept constant as vehicle loading varies.

Struts

A strut is a structural piece designed to resist pressure in the direction of its length. On a typical "MacPherson Strut," the shock absorber is built into the strut. Most are hydraulic units (some Fords use gas filled shock struts). They are nonadjustable and non-refillable. All faulty struts must be replaced as an assembly. Another similar front suspension system is called the "hydraulic shock strut" and serves as a shock absorber which also replaces the upper control arm.

Control Arms

A control arm is a bar with a pivot at each end, used to attach suspension members to the chassis.

When coil springs are used in both front and rear suspension, 3 or 4 control arms are placed between the rear axle housing and the frame to carry driving and brake torque. The lower control arms pivot in the frame members and sometimes support the rear coil springs to provide for up and down movement in the axle and wheel assembly.

Springs

Compression type coil springs may be mounted between the lower control arm and spring housing or the seat in the frame. Other front suspension systems have the coil springs mounted above the upper control arms.

Leaf springs are used on trucks and some cars. They also serve as control arms, locking the rear end in position.

Sway Bars

Some cars require stabilizers to steady the chassis against sway when turning. Stabilizers are designed to control this rising action on the side toward the inside of the turn. When the car turns and begins to lean over, the sway bar uses the upward force on the outer wheel to lift on the inner wheel, thus keeping the car more level.

Torsion Bars

Torsion bar suspension uses the flexibility of a steel bar or tube that twists lengthwise to provide spring action.