Chevrolet 1977 light duty truck Service Manual page 287

stroked, a lag is noticed, it means the gas-filled cell has
been ruptured, and the shock should be replaced. If no
lag is noticed, the re m ain der o f the bench check is the
same as given in the Spiral Groove Reservoir, Section 1,
Bench Check Procedure.
AIR A D JUSTAB LE SHOCKS
This type o f shock contains an air cham ber like the
spiral groove reservoir type, and must have the air
p urged from the working cham ber. See Section 1, Spiral
G roove Reservoir. A fter air has been purged from shock,
proceed as follows:
(a) C lam p lower shock m ounting ring in vise in
vertical position with larger d iam eter tube at the top.
(b) Pum p unit by hand at different rates o f speed.
Smooth resistance should be felt through the length of
the stroke. Since the units are normally pressurized, the
sound o f air bubbles or a gurgling noise is
(c) The re m a in d e r o f the bench check is the same
as given in the Spiral Groove Reservoir, Section 1, Bench
Check Procedure.
BEARINGS AND RACES
BENCH D IA G N O S TIC PRO CEDURE
This section describes com m on types of bearing
distress and their causes. Illustrations are included to
help diagnose the cause o f distress and comments are
provided to help make elfective repairs.
Consider The Following Factors When
Diagnosing Bearing Distress:
1.
teardown and examinations.
2.
illustrations where possible.
3.
permit correction o f the problem and prevent a repeat
failure o f the same type.
4.
procedures.
Com m on Causes For Bearing Distress
Include The Following:
1.
norm al
2.
3.
4.
5.
6.
7. Corrosion or rusting.
8. Seizing or sm earing from overload.
9. Overheating causing tempering.
10.
11.
12.
Note G eneral Condition o f all parts during
Classify the failure with
D etermine the cause. Recognizing the cause will
M ake all repairs following
Im proper adjustm ent or preloading.
M ounting or teardown abuse.
Im proper m ounting methods.
Inadequate or wrong lubricants.
Entrance o f dirt or water.
W ear from dirt or metal chips.
Frettage o f bearing seats.
Brinelling from impact loads and shipping.
M anu facturin g defects.
the aid o f these
re c o m m e n d ed