GMC 1976 ZEO 6083 Maintenance Manual page 133

3A- 4 FRONT SUSPENSION
Problem
Possible Cause Correction
Shock Absorber-Weak. 1 . Low or uneven tire 1 . Inflate tires to the proper
pressure . recommended pressure .
2. Excessive or incorrect 2. Instruct driver .
vehicle loading.
3. Worn out shock 3. Perform on vehicle test . Push
absorber . Front. down and lift up at end of bumper
nearest front shock in question .
right and left shocks must be
comparable in rebound resistance
to compression ration (usually
2 to 1) . If in doubt compare with
vehicle having acceptable ride
quality.
4. Worn out shock 4. Disconnect the lower shock
absorber . Rear. mountings. Stroke shocks at various
rates of speed through maximum
travel in both directions . Compare
side to side for rebound and
compression resistance . Rebound
resistance is normally stronger
than compression (approximately
2 to 1) . It is mandatory that right
and left shocks feel comparable.
If in doubt about condition,
compare with a known good shock.
Shock Absorber-Noisy . 1 . Loose mounting . 1 . Check all shock mounting
torques (bolt and/or nut) .
2. Faulty shock absorber
2. Observe hoisting instructions
and instructions for removal of
front shock absorbers. Clamp shock
upside down . Clamp vise on top
mount with shock vertical in vise
(do not clamp on reservoir tube).
Rear shocks may be tested on the
vehicle by disconnecting the lower
mount. Completely extend to full
rebound then exert an extra pull .
If a "GIVE" is felt a loose
piston is indicated and the shock
should be replaced . A hissing noise
(orifice swish) is normal, however,
replace shock absorber for any of
the following:
1 . A skip or lag at reversal
near mid-stroke.
b . A seize (except at either
extreme end of travel).
c. A noise such as a grunt or
squeal after completing one full
stroke in both directions.
d. A clicking noise at fast
reversal .