Chevrolet 70 1969 Series, Shop Manual

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STEERING 9-21
NOTE: Due to the low torque adjustment and
because it would be difficult to get an accurate
reading on wrench, do not use a torque
wrench having maximum torque reading over
100 inch-pounds. When taking the following
torque readings, take a reading pulling the tor­
que wrench to the right and a reading pulling
the torque wrench to the left. Total both read­
ings and take one-half of this total as the aver­
age torque.
Using a 3 /4 inch - 12 point deep sccket and (J-6459)
inch-pound torque wrench (fig. 23), adjust lash adjuster so
torque is between 4-8 inch-pounds in excess of total b ear­
ing preload and valve drag readings previously recorded.
This P itm an shaft preload reading should be taken with
the gear on center and while rotating the steering shaft
through an arc of not m ore than 10 degrees.
Tighten lash adjuster lock nut to 25-35 foot-pounds to r­
que. T he final over-center reading, which represents the
total of the valve an d seal drag, the worm bearing pre­
load, and the lash adjuster preload, should not exceed 16
inch-pounds.
VANE TYPE HYDRAULIC PUMP
HYDRAULIC PUMP OVERHAUL
(Figures 1 and 2)
DISASSEMBLY
Key num bers in text refer to Figure 2.
1. Carefully m ount pum p assem bly in a vise with soft
jaw s and remove reservoir filler cap (1), if used.
NOTE: When damping pump in vise, do not
exert excessive force on hub as this may distort
the drive shaft bearing in housing.
2. Remove rear m ounting stud (3) from reservoir (6)
(fig. 3). Remove seal (2) from m ounting stud and dis­
card.
3. Remove pressure fitting and orifice assem bly (5) and
inner seal (4) (fig. 4). Discard O-ring seal.
4. Rem ove pum p reservoir and tube assem bly (6) from
pum p housing. It will be necessary to rock the assem ­
bly back and forth to aid in removal (fig. 5).
NOTE: Do not scratch inside surface of reservoir
on sharp corners of pump casting as this may
cause an oil leak at reservoir to pump housing
oil seal (8).
5. Rem ove m agnet (7) from reservoir.
6. Remove pressure union outlet seal (18) from control
valve cavity in pum p housing. Discard seal.
7. Using a small punch, depress end plate retaining ring
(9)
enough to allow rem oval from groove in pum p
housing. Insert punch in 1/8 inch diam eter hole in
housing and remove retaining ring with a screwdriver
(fig. 6).
8. Rem ove end plate (10) (fig. 7). End plate is sprin-
gloaded and will usually sit above housing level. If
end plate sticks, a slight rocking action should free it.
NOTE: If rocking action fails to free the plate,
use a magnet to free it.
9.
Rem ove two pressure plate springs (12) from pum p
housing.
10. R em ove housing assembly (23) from vise and remove
flow control valve (21) and spring (22) by inverting
housing (fig. 8).
NOTE: Do not disassemble the flow control
valve. Valve is serviced as a unit and is pre-set
at the factory.
11. W ith pum p housing (23) still inverted, tap lightly to
remove pressure plate (13), pum p ring (15), pum p
rotor (16), pum p vanes (17), pum p rotor thrust plate
(19) and two dowel pins (20) (fig. 9). •
12. Remove shaft and bearing retaining ring (28).
13. Place pum p housing (23) in press and remove drive
shaft (29) and ball bearing (27) as an assembly.
14. Rem ove bearing retaining ring (26) from shaft (29)
and press shaft out of bearing (27).
15. Place housing in press and, using suitable tool, press
needle bearing (24) and oil seal (25) out of housing
(23).
16. Remove shaft key (30) from drive shaft (29).
17. Rem ove end plate seal (11) and pressure plate seal
(14) from grooves inside pu m p housing. Discard seals.
NOTE: There is only a slight difference in size
of pressure plate seal (14) and end plate seal
(11). Both are the same thickness but I.D. of
pressure plate seal (14) is 2.862 inches plus or
minus .015 inches while I.D. of end plate seal
(11) is 2.924 inches plus or minus .015 inches.
18. Rem ove reservoir seal (8) from groove on outside of
pum p housing (23). Discard seal.
CLEANING AND INSPECTION (Refer to Fig. 2)
1. Clean all parts except the drive shaft oil seal in clean­
ing solvent. N O T E : T he drive shaft oil seal will be
dam aged if im m ersed in cleaning solvent.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P M A N U A L