Chevrolet Light Duty Truck 1973, Service Manual

Page: 325 / 979

BRAKES 5 -5 9
DIAGNOSIS—DISC BRAKES
DRAGGING BRAKES (CONT.)
Probable Cause Rem edy
3. I n c o r r e c t parking brake adjustment on r e a r brakes. 3. Check and r e a d j u s t to c o r r e c t s p e c i f i c a t i o n s .
4. Metering valve i n s t a l l e d i n c o r r e c t l y . 4. Port marked " i n l e t " goes to master c y l i n d e r , Port
marked " o u t l e t " goes to d is c c a l i p e r s .
5. Check valve i n s t a l l e d in o u t l e t to f r o n t d is c brakes. 5. Check o u t l e t hole and remove check v a lv e , i f l i n e is
connected to d is c brake c a l i p e r s .
G RABBING OR UNEVEN BR AKING A C T IO N
Probable Cause Rem edy
1. A l l c o n d itio n s l i s t e d under "PULLS".
2. M a lfu n c tio n o f metering valve o r p r o p o r tio n in g v a lv e .
3. M a lfu n c tio n o f power brake u n i t .
4. Binding brake pedal mechanism.
5. Metering valve not ho ld in g o f f f r o n t brake a p p l i c a t i o n .
1. See "PULLS".
2. Replace and bleed system.
3. Check o p e ra tio n and r e p a i r , i f necessary.
4. Check and l u b r i c a t e w i th Delco Brake Lube #5450032
(or e q u iv a le n t ) i f necessary.
5. Replace metering valv e and bleed system. I f v e h ic le
is not equipped w i t h metering v a lv e , check o th e r
causes.
REAR DRUM BRAKES SKIDD IN G PREMATURELY UNDER HARD BRAKE APPLICATION
Probable Cause Rem edy
1. P ro p o r tio n in g valve not c o n t r o l l i n g r e a r l i n e pressure 1. Replace p r o p o r ti o n i n g valve and bleed system. I f
to prevent r e a r wheel lockup on hard brake a p p l ic a t io n s
v e h ic le is not equipped w i th p r o p o r ti o n i n g v a lv e ,
check o th e r causes l i s t e d under "PULLS" or "GRABBING
OR UNEVEN BRAKING ACTION".
LIGHT DUTY TRUCK SERVICE MANUAL