Shock Absorber


This is usually a rather simple job requiring the removal of only two or three nuts or bolts. Two types of problems occur to make shock absorber replacement difficult or possibly hazardous: removal of the nut on single-stud mounts and the possibility of a sudden dropping of the suspension as the shock absorber is removed.

The nut on single-stud shock absorber mounts tends to rust and seize in place. Its removal is made more difficult because the stud and piston rod will often rotate during removal attempts. The polished piston rod should never be gripped with plain or locking pliers. The smooth surface will be damaged, which in turn will ruin the upper shock absorber bushing and seal, and the polished surface is too smooth to grip tightly. There are several approved ways of removing this nut; begin by applying penetrating oil to the threads. Next try one of these methods:

  1. Often a fast-operating air wrench will spin the nut off.
  2. The shock absorber stud has two flats on the end, which can be held using a special wrench or socket.
  3. If the nut is rusted in place, the shock stud can be broken off by replacing a deep-well socket with extension bar over the nut or thread, onto the exposed threads of the stud. Bend the shock stud back and forth until it breaks off; this, of course ruins the shock absorber.
  4. A nut breaker can be placed over the nut and tightened to break or snap the nut open for easy removal.
  5. An air impact hammer and chisel can be used to cut down each side of the nut until the nut snaps or is cut into two parts.

To remove the shock absorbers, you should:

  • Raise and support the car securely on a hoist or jack stands.
On those cars where the upper-front shock absorber mounts can be reached from under the hood, it is often faster to disconnect the upper shock absorber mount before raising the car.
  • Disconnect the upper shock absorber mount, if it is not already done.

While removing the nut on stud-type mounts, observe the rubber bushing; if it stays under a compression load while the nut is being removed, the suspension will probably drop when the nut leaves the threads. In this case, it is best to lift the suspension slightly or lower the body to remove this load.

  • At times it is necessary to purge the air out of the pressure tube of a double-tube shock absorber; this is also called bleeding a shock absorber.
  • Check the bushings and other pieces of shock absorber mounting hardware to make sure they are in good condition and assemble these parts in the proper relationship.
  • Place the shock absorber with bushings in position and connect the upper mount. On single-stud mounts, tighten the nut to compress the rubber bushing, but not too much. The correct amount of tightness will squeeze the rubber bushing to about the same diameter as the metal washer. If the nut has not tightened securely against a metal shoulder or sleeve at this point, or if a self-locking, prevailing torque nut is not used, a jam or a pal nut should be used to lock the retaining nut in position.
  • Place the lower bushings in position and connect the lower shock absorber mount. Tighten the retaining nut(s) or bolt(s) to the correct torque.

MacPherson Struts

A large majority of vehicles have MacPherson struts. The MacPherson struts are a style of shocks used for vehicles with a triangular design suspension system. The strut assembly is a structural member that does away with the upper control arm bushings and the upper ball joint.

To remove and replace the MacPherson strut, proceed as shown below.

The top of the strut assembly is mounted directly to the chassis of the car.

Prior to loosening the strut to the chassis bolts, scribe alignment marks on the strut bolts and the chassis.

With the top strut bolts or nuts removed, raise the car to a working height. It is important that the car be supported on its frame and not on its suspension components.

Remove the wheel assembly. The strut is accessible from the wheel well after the wheel is removed.

Remove the bolt that fastens the brake line or hose to the strut assembly.

Remove the strut's two steering knuckle bolts.

Support the steering knuckle with wire and remove the strut assembly from the car.

Install the strut assembly into the proper type spring compressor. Then compress the spring until it is possible to safely loosen the retaining bolts.

Remove the old strut assembly from the spring and install the new strut. Compress the spring to allow for reassembly and tighten the retaining bolts.

Art courtesy of Delmar - Thomson Learning.

Reinstall the strut assembly into the car. Make sure all bolts are properly tightened and in the correct locations.