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5 -5 8 BRAKES
Probable Cause
4. Rear drums o u t-o f- ro u n d .
5. Shoe reversed (s te e l ag a in s t ir o n ) .
Probable Cause
1. M alfu nctio nin g power brake.
2. P a r t ia l system f a i l u r e (dual master c y l i n d e r ) .
3. Excessively worn shoe and l i n i n g .
4. Pistons in c a lip e r s stuck or slu g g is h .
5. Fading brakes due to i n c o r r e c t l i n i n g .
Probable Cause
1. P a r t ia l brake system f a i l u r e (w ith dual system master
c y l i n d e r s ) .
2. I n s u f f i c i e n t f l u i d due to leak in system.
3. In c o rr e c t master c y li n d e r push rod adjustment.
4. A i r trapped in system.
5. Rear brake not a d ju s tin g p ro p e rly .
6. Bent shoe and l i n i n g .
(A very l i g h t drag is present in a l l disc brakes immediately a f t e r pedal is released)
Probable Cause
1. Master c y li n d e r pisto ns not r e tu r n in g c o r r e c t l y .
2. R e s tricte d brake tubes or hoses.
DIAGNOSIS—DISC BRAKES
BRAKE ROUGHNESS, ETC. (C O N T .)
4. Check runout and i f not w i t h i n s p e c i f i c a t i o n s , t u r n the
drums.
5. Replace r o t o r and shoe and l i n i n g .
EXCESSIVE PEDAL EFFORT
.
1
Check power brake and r e p a i r i f necessary.
2. Check f r o n t and rea r brake system and r e p a i r i f
necessary.
system is found and l i g h t did not f u n c t i o n .
3. Check and replace in axle sets.
4. Remove c a lip e r s and r e b u i ld .
5. Remove and repla ce w ith o r i g i n a l equipment.
EXCESSIVE PEDAL TRAVEL
.
1
Check both f r o n t and rea r systems f o r a f a i l u r e and
r e p a i r .
equipped.
2. F i l l r e s e rv o ir s w ith G M Hydraulic Brake F lu id Supreme
No. 11 (or e q u i v a l e n t ) .
3. Adjust c le v is where po ssib le .
4. Bleed system.
5. Adjust re a r brakes and r e p a i r auto a d ju s te r s .
6. Replace axle set o f shoe and l i n i n g .
D R A G G IN G BRAKES
.
1
With r e s e r v o ir cover o f f , check f o r f l u i d s p u r t a t bypass
holes as pedal is depressed.
necessary or r e b u ild master c y l i n d e r .
2. Check f o r s o f t hoses or damaged tubes and repla ce w ith
new hoses and new doub le-walled stee l brake tu b in g .
Remedy
(Not over maximum o f .060 on the d ia m e te r.)
Remedy
Also check brake warning l i g h t i f a f a i l e d
Remedy
Also check warning l i g h t , i f v e h ic le is so
I t should have in d ica te d a f a i l u r e .
Remedy
A d ju s t push rod, i f
LIGHT DUTY TRUCK SERVICE MANUAL
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