Control Valve Assembly - Chevrolet 1980 Light Duty Truck Repair Manual

7A1-42 AUTOMATIC TRANSMISSION (200)

Control Valve Assembly

Disassem bly
NOTICE:
A s each valve train is removed, place the
individual valve train in the order that it is removed and
in a separate location relative to its position in the valve
body. N on e o f the valves, bushings or springs are
interchangeable; some coiled pins are interchangeable.
R em ove all coiled pins by pushing through from the
rough cast surface side o f the control valve assembly,
except the 2 pins which retain the throttle valve and
throttle valve plunger.
1. R em ove the 4 check balls.
2. Position control valve assembly as shown in Figure
7A 1-165.
3. R em ove 1-2 accum ulator piston.
4. R em ove manual valve from valve from upper bore.
NOTICE:
Some o f the coiled pins in the control valve
assem bly have pressure against them. Therefore, hold
a shop towel over the bore w hile rem oving the pin, to
prevent possibly losing a bore plug, spring, etc.
5. R em ove coiled pin from upper right bore. Rem ove
2-3 throttle valve bushing, 2-3 throttle valve spring, 2-3
throttle valve and 2-3 shift valve.
NOTICE:
The 2-3 throttle valve spring and 2-3 throttle
valve m ay be inside the 2-3 throttle valve bushing.
6. From next bore down, rem ove coiled pin. R em ove
1-2 throttle valve bushing, 1-2 throttle valve spring, 1-2
throttle valve and 1-2 shift valve.
NOTICE:
The 1-2 throttle valve spring and the 1-2
throttle valve may be inside the 1-2 throttle valve
bushing.
7. From next bore down, rem ove coiled pin and bore
plug. Rem ove reverse boost spring and reverse boost valve.
8. Check the operation o f the shift T.V. valve in the next
bore down, by m oving the valve against the spring. If it is
necessary to remove the valve, proceed as follows: (Figures
7A 1-166 and 7A 1-167).
a. Rem ove coiled pin and place valve body on shop
towel with rough casting surface up.
b. U sing needle nose pliers, compress the shift T.V.
spring by pushing on the shift T.V. valve; hold valve with
sm all screwdriver. (Figure 7A 1-166).
c. Place 6.3m m (1 /4 " ) rod, 9.5m m (3 /8 " ) long, against
the end o f the shift T.V. valve.
d. Prying on end o f the rod with a large screwdriver,
rem ove sm all screwdriver and remove shift T.V. plug, shift
T.V. spring and shift T.V. valve (Figure 7A 1-167).
e. D iscard shift T.V. plug and rem ove 6.3mm (1 /4 " )
rod from shift T.V. bore.
9. From next bore down, remove outer coiled pin.
R em ove the throttle valve plunger, bushing and throttle
valve spring. U sing a 1.5mm (1/16" ) alien wrench with
ground sides to fit inside the pin, rem ove the inner coiled
pin. (Figure 7A 1-168). R em ove the throttle valve.
10. From upper left
interm ediate boost spring and intermediate boost valve.
11. From next bore down, remove coiled pin, low
overrun clutch spring and low overrun clutch valve.
12. From next bore down, rem ove coiled pin, direct
clutch exhaust spring and direct clutch exhaust valve.
13. From next bore down, rem ove coiled pin, valve bore
plug, 1-2 accum ulator valve and 1-2 accum ulator valve
spring.
Inspection
1. W ash control valve body, valves, springs, and other
parts in clean solvent and air dry.
2. Inspect 1-2 accum ulator piston for damage.
3. Inspect 1-2 accum ulator piston seal for damage and
free fitting groove. D o not remove seal unless replacing.
4. Inspect valve for scoring, cracks and free m ovem ent
in their bores.
5. Inspect bushings for cracks or scored bores.
6. Inspect valve body for cracks damage or scored
bores.
7. Inspect springs for distortion or collapsed coils.
8. Inspect bore plugs for damage.
Pin
Reassem bly
NOTICE:
Install all flared coiled pins (zinc coated)
flare end out, and from the m achined face o f the control
valve assembly. Install the tw o (2) tapered coiled pins
(black finish) that retain the throttle valve bushing,
tapered end first. Coiled pins do not fit flush on rough
casting face. M ake sure that all coil pins are flush at
machined face.
1. Position control valve body as shown in Figure 7A 1-
165.
2. Install into lower left bore, 1-2 accum ulator spring,
1-2 accum ulator valve, sm aller stem end out. Install bore
plug, hole out, and coiled pin.
3. In next bore up, install direct clutch exhaust valve,
longer stem end out, direct clutch exhaust spring and coiled
pin.
4. In next bore up, install low overrun clutch valve,
longer stem end out, low overrun clutch spring and coiled
pin.
5. In next bore up, install interm ediate boost valve,
longer stem end out, interm ediate boost spring and coiled
pin.
6. In lower right bore, install throttle valve, smaller
outside diameter land first, making sure valve is seated at
the bottom o f the bore. Install inner coiled pin between the
lands o f this valve. (Figure 7 A 1-168). Install the shift T.V.
spring into the bore. Install the throttle valve plunger, stem
end first, into the throttle valve plunger bushing and install
these 2 parts into the bore, valve end first. Install outer
coiled pin from rough cast surface side, aligning pin with
slot in bushing.
7. In next bore up, if removed, install shift T.V. valve,
larger outside diameter stem end out, shift T.V. spring and
bore, remove coiled pin,