Checking The Shock Absorbers; Replacing Front Shock Absorbers - Volvo 164, 1970 Service Manual

FUNCTION
When the shock absorber is compressed or extended
thro ug h th e suspens ion of t he ve hi cle, t he p iston (5)
is moved in th e inner cylinder (2) . Fluid the n f lows
through t he va lve-contro lle d ho les in the piston. The
speed w ith whic h the p iston moves is determ ined by
the rate at w hi ch the f lui d passes thro ugh t he ho les
fro m o ne side of the piston to th e oth er. Since th e
d rill ed ho les are ve ry narrow, th e flui d can on ly
pass t hro ug h s low ly, thu s bra king t he move ment of
th e p iston . Wh e n the s hoc k a bsorb er is sudde n ly
compressed or exte nded, a f urth er braki ng eff ect is
caused by turbu lence in the fluid passing through
the holes in the p iston. This dampens any rolling
tendency on the part of t he vehicle and ensures
smoot he r rid ing .
When t he shock abso rbe r is compressed or exten ded,
the vo lu me on each side of the piston is not a lte red
by t he same amo unt since the piston rod occupies a
certa in space. Wh en the shock absorber is compres-
sed , t he refo re, som e of t he f lui d passes o ut throug h
the va lve (6) into t he reservo ir, and when the shock
a bso rbe r is exte nded , flu id is aga in sucked into t he
cylin der (2) on the und ers ide of the piston.
REPAI R I NSTRU CTI O N S
CHECKING THE SHOCK ABSORBERS
Accurate checking of the shock absorbers can only
be carried out with special checking devices . A rough
check, however, can be made in order to see that the
shock absorbers are functioning on the whole by
noting the damping effect when rocking the car up
and do w n and the n releasing it. Testing can also be
carried out by driving the vehicle over a bumpy sur-
face. The removed absorber can be tested by tightly
fixing the lower attachment in a position similar to
that wnen fitted in the vehicle . If it is the n alternately
pulled out and compressed, it is possible to judge
whether it is operating or not. Notice on making this
check that, when the shock absorber is extended, its
resistance is three times as great as when it is com-
p ressed, this due to its way of operating.
If the shock absorber does not function satisfactorily
in both directions, or if the fixed rubber bushes are
damaged, the sh ock absorbers should be replaced .
REPLACING FRONT SHOCK ABSORBERS
l. Remove the upper nut (4, Fig
. 7-7), the washer (3)
and the rubber bush (6).
2. Remove the two lower attaching screws (Fig . 7-8)
7 :6
3
2
Fig . 7·7. Upper attachment, fron t shock absorber
1. Rubbe
r bu sh 5. Spi ndle
2. Spac ing sleeve 6. Rubber bush
3. Washer 7. Washer
4. Nu!