Chevrolet 1980 Light Duty Truck Repair Manual page 117

CASE HALF — L.H
SHIM
ASSEMBLY
directions. W heel should rotate freely. If both wheels
attem pt to turn together, the differential is locking and is
defective.
Rapid wheel rotation will cause a properly operating
differential to lock and both wheels will rotate in the same
direction.
3. R aise hoist to m axim um height with one person in
vehicle.
4. Start engine making sure that carburetor is set to
provide a low idle speed o f 600-800 rpm.
5. Place transmission in drive range and apply brakes.
W ith m anual transmission, depress clutch
transm ission in first gear.
6. Lock one rear wheel by pulling one parking brake
cable from under the vehicle.
7. W ith engine at low idle, slow ly release brakes. W ith
m anual transmission, slow ly engage clutch.
8. Locked rear wheel w ill remain stationary and free
wheel w ill begin turning. It is important that brakes or
clutch be released slow ly enough to start the free wheel
turning and allow the free wheel to gradually increase in
speed. A s speed o f the free wheel is increased, the
differential will lock causing the rotating wheel to stop or
both w heels to turn at the same speed. The engine may stall
if equipped with a manual transmission. It may be necessary
to accelerate engine until approximately 10 mph is indicated
GUIDE CLIP (6)
EARED
j) \ DISC (3)
SPLINED DISC (2)
LATCHING
BRACKET
F ig . 4 B - 2 H - - 3 / 4 T o n U n it
and place
REAR AXLE DIFFERENTIAL
GUIDE CLIP (6)
DISC
PACK S/A
CASE
HALF — R.H
GOVERNOR
ASSEMBLY
SIDE GEAR
THRUST BLOCK (2)
on vehicle speedom eter to cause differential lock.
indicated speed can be increased beyond 20 mph (32 k m /h )
w ithout causing differential lock, the unit is not functioning
properly.
Rapid release o f brakes or clutch, or rapid acceleration
o f engine will invalidate test.
9. L ock o p p o site rear w heel an d re p e a t p ro c e d u re . The
follow ing c h a rt p ro v id es guidelines fo r diagnosis an d rep air
o f d iffe re n tia l c o m p lain ts
O V E R H A U L P R O C E D U R E S 8 - 7 /8 R IN G GEAR
AX LE 1 /2 TO N T R U C K S
D ue
dim ensions, differential side gears and case cannot be
serviced separately. If any side gear or case damage is
found, the entire differential must be replaced.
In te rn a l clearances are su ch th a t shim s, re a c tio n b lo c k ,
and th ru s t rings sh o u ld n o t be rep laced unn ecessarily
even if slight w ear in d ic a tio n s are p resen t. I f shim s,
re a c tio n b lo c k , o r th ru s t ring m ust b e replaced due to
dam age, c o rre c t m e a su rem en t
ced u res m u st be fo llo w ed . F ailu re to do so m ay d istu rb
critical clearances
co m p lain ts.
4B-49
SCREW (3)
SHIM
'
\
THRUST
WASHER (3)
PINION
'GEAR (3)
PINION YOKE
to critical internal clearance
and rep la cem e n t p ro ­
and c o u ld result in d iffe re n tia l
O V E R H A U L M A N U A L
If