inside a MacPherson
wears out, you can buy a replacement cartridge which — depending on type — may or may not include new parts for the strut itself.
You will need a pair of
. Hire them if necessary, do not use makeshift arrangements of clamps, wire or cord. They are unsafe.
Loosen the wheel nuts and raise the car on
Remove the wheels, and open the bonnet or boot lid to gain access to the
from above and below.
Removing a standard strut
Unscrew the three nuts above the mounting to release the top of the strut. Do not loosen the central nut between them, which would release the
spring from the strut.
Remove the two bolts underneath the track
, which fix the strut to the arm.
At this stage, examine the suspension before proceeding further: on several cars there is no need to disconnect any of the steering
or the anti-roll bar (if fitted).
On others the track-rod end, and sometimes the track control arm or anti-roll bar or both, must be detached.
Clamp the flexible
to close it. Use a brake-hose clamp.
from the rigid brake pipe on the strut by unfastening the union nut.
Lift the strut and the brake assembly from the track control arm. Be careful - they are heavy. You may need a helper.
the brakes and top up the
Removing a unit-replacement strut
Unscrew the two nuts (on some cars three) above the top mounting turret to release the top of the strut.
Do not unscrew the central nut between them, which would release the coil spring.
The top part of the strut is fixed to the bottom part by bolts - there may be one, two or sometimes three.
The lower, or lowest bolt may be
, as a means of adjusting the
. Mark its head so that you can refit it in exactly the same position.
Remove the nuts and pull out the bolts to free the top half of the strut.
Removing and refitting a damper
Clamp the strut in a vice with the upper end higher than the lower end to prevent the oil running out.
a pair of spring compressors round at least four coils of the spring, and tighten evenly until the spring is well compressed and tension on the upper spring mount is released.
Then unscrew the central nut at the top of the damper; on a unit-replacement strut it must be unscrewed with an Allen key.
Lift off the top spring
, and the upper
if applicable. Then lift off the compressed spring.
If there is a rubber gaiter round the damper, remove this too.
Free the damper from the strut by unfastening the large gland nut between its two telescopic sections.
If you do not have a spanner that fits the nut, put it in the vice and turn the strut. If the nut is rusty,
will help to free it.
Check the threads on the strut tube for damage, and clean them.
You may now be able to remove the damper as a single, sealed unit. If so, clean the inside of the strut with petrol, let it dry and put in the new damper cartridge.
Alternatively, you may have to dismantle the old damper to remove it, but it is not difficult to fit the replacement cartridge, because it is in one piece and includes a replacement
Read the instructions on the cartridge box. They may tell you to pour oil into the strut casing - usually 2fl. oz (50ml) of light
oil or special damper oil - to cool the cartridge and prevent corrosion.
Refit the gland nut. Fix it firmly by denting the outside of the casing in one spot with a hammer and punch.
Refit the spring. Make sure it is set straight, then decompress it evenly. Fit the top spring platform, nut and
pieces. Then tighten the centre nut fully.
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The suspension system affects both the driver's control of the car and the comfort of the occupants. The springs allow the wheels to move up to absorb bumps in the road and reduce jolting, while the dampers prevent bouncing up and down. Various mechanical links keep the wheels in line.
There are various ways of attaching the wheels of the car so that they can move up and down on their springs and dampers, and do so with as little change as possible in the distance between adjacent wheels or in the near-vertical angle of the tyres to the road.