Worn or damaged shock absorbers are dangerous, have
them checked on a regular basis. Worn shock absorbers
allow the wheels to bounce and the body to roll and
pitch. Tyre wear is accentuated due to the irregular
battering encountered and braking efficiency is drastically
reduced due to tyre-to-road contact being inadequate.
Here are a few important points to look for:
LOOSE OR DAMAGED MOUNTINGS
Check that the fastenings are firm, rubbers are not
missing and that all bolts are tight. The shock absorber
will not do its job unless it is fastened correctly.
LEAKING SHOCK ABSORBER
Look for tell-tale smears on the unit. Make sure they
come from the body of the shock absorber and have just
not been thrown up from the road, sump or transmission.
TEST METHOD
Where a test machine is not available an approximate
idea of the condition of the shock absorbers can be
obtained by the following method:
Bounce each corner of the car several times, releasing
at the bottom of the stroke. Each corner should rebound
to the top of its stroke and then settle in the normal
position. If it bounces more than this, the shock absorber
needs to be replaced.
If the car is difficult or impossible to bounce then
the shock absorber has probably seized or has a bent
piston rod perhaps due to a faulty mounting bracket.
Always use the correct tools for any job, this can
never be overstressed. Shock absorber fitment is no
different. The following tools will make the fitment
much easier:
There are three main types of shock absorbers, namely;
the wet strut, the sealed strut and the telescopic.
Refer to the owner's manual for the type in your vehicle.
1. REPAIRING A WET STRUT
Here are the steps to the follow for wet strut repair.
Step 1. Loosen the piston rod nut and loosen
one turn using the correct size socket spanner. Loosen
the wheel nuts. Jack up the car and make a match mark
on one of the bolts and the rim before you remove the
wheel. Use axle stands for safety.
Step 2. Clamp the coil spring with a spring
compressor. Clamp the brake hose and remove the spring
clip, disconnect the brake hose fittings, do not spill
brake fluid, as it is corrosive.
Step 3. Disconnect the steering arm from the
strut by removing the bolts. Remove the top three nuts
and mark their position. Now, remove the strut together
with the brake assembly, by lifting them out.
Step 4. Move to a workbench and remove the old
internal parts. Clamp the strut in a strut clamp, compress
the coil spring until it moves freely, and remove the
piston rod nut. Note the position of the disassembled
components so that they can be replaced in the correct
sequence.
Step 5. Using the correct size spanner, remove
the gland screw, take care as it may have to be re-used.
The function of the gland screw is to centralize and
clamp the internals. Remove the old internals and check
for compatibility against the new insert.
Step 6.
Drain the oil and discard it. Clean out the tube and
threads with a solvent. Refill the tube with the necessary
amount of oil, either Midas SAE 30 or a suitable equivalent.
The new insert can be slid into position.
Step 7.
Carefully re-fit the gland screw and torque it to the
correct specification. Ensure that the new insert is
firmly positioned in the tube and make sure that the
piston rod is centered with the correct amount of thread
exposed. Prime the unit well to get the oil circulating.
Step 8.
Align the spring with the seat hollows. Grease the bearings.
Tighten the top nut just enough to secure the assembly.
The unit can now be installed into the vehicle.
Step 9. Once securely positioned, the top three
securing nuts should be tightened to the correct specification.
Refit the steering arm to the strut knuckle and tighten
the piston rod nut to correct specification. Replace
the dust cap.
Step 10.
Reconnect the brake hose fitting and replace the spring
clip. Refit the wheel, make sure the match marks are
aligned. Lower the vehicle and tighten the wheel nuts.
Step 11.
Bleed the brake line. It is recommended that the tyre
pressure and wheel alignment be checked and the car
test-driven. The wet strut repair is now complete.
REPLACING A SEALED STRUT
Here are the steps to follow for front sealed strut
replacement:
Step 1.
The procedure up to this stage is exactly the same
for the sealed strut as it was for the wet so we can
go straight onto disconnecting the brake hose. Clamp
the hose, remove the spring clip and disconnect the
brake hose.
Step 2.
Note the position of the adjustment cam by making
a notch on the lower bracket. Support the suspension
with a jack to prevent it from dropping. Remove the
two securing bolts. The sealed strut can now be removed
from the steering knuckle and lifted out.
Step 3.
On a workbench clamp the strut in a strut clamp and
compress the coil spring until it moves freely. Remove
the top nut and disassemble the components noting
their position. Remove the old strut from the strut
clamp and compare it with the new unit. Now place
the new unit in the strut clamp.
Step 4.
Ensure that the new unit is well primed and carefully
replace the components in the correct sequence, checking
them for wear or damage. Ensure that the coil spring
is aligned with the lower seat hollow. The "out"
marked stamped on the upper spring seat must face
the outside of the vehicle. Tighten the top nut just
enough to secure the assembled strut.
Step 5.
Remove the spring compressor, the sealed strut is
ready for refitting. Tighten the top three nuts to
the correct specification. Refit the steering knuckle
to the lower bracket. Apply oil to the bolt threads
and insert them from the rear side. Align the adjustment
cam on the steering knuckle with the notch previously
marked on the lower bracket and tighten the nuts according
to specification. Finally, torque the piston rod nut
to the manufacturer's specification and replace the
dust cap. Reconnect the brake hose fittings and replace
the spring clip. Bleed the brake line and it is recommended
that the tyre pressure and wheel alignment be checked
and the car test-driven.
2. REPLACING A TELESCOPIC SHOCK ABSORBER
Fitting a telescopic shock absorber is a lot easier
than fitting wet or sealed struts. However, there's
always those small but important points to keep in mind.
Don't forget to lubricate the bushings, use a rubber
lubricant, not oil.
For stud applications, the top mounting should be
fully tightened only when the full weight of the car
is on wheels.
And remember, don't over tighten the bushings.
When fitting adjustable shock absorbers please follow
adjustment instructions on package ( 4 settings).
General notes:
To remove nuts, use Loctite penetrating oil. Never
burn them off. For stubborn nuts use a "nutcracker"
and throughout the job, always use the correct tools.
Before installing the new unit, make sure it's the
correct one for the vehicle.
Prime the unit before fitting it and check all components
before replacing them - if they're old and worn, they
too should be replaced.
Don't grip the piston rod with pliers or place the
unit itself in a vise, you'll damage it .
Midas Motor Parts Centres recommend ARMSTRONG SHOCK
ABSORBERS.
INDEMNITY
Remember this is for information only, for more details
consult the workshop manual for your vehicle.