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If a lined drive plate exhibits any of the above conditions,
replacement is required.
IMPORTANT: Do not diagnose drive plates by color.
B. Steel Driven Plates
Wipe plates dry and check for heat discoloration. If the
surface is smooth and an even color smear is indicated, the
plate should be reused. If severe heat spot discoloration or
surface scuffing is indicated, the plate must be replaced.
C. Clutch Release Springs
Evidence of extreme heat or burning in the area of the
clutch may have caused the springs to take a heat set and
Causes of Burned Clutch Plates
A. Check ball in clutch housing damaged, stuck or
missing.
B. Clutch piston cracked, seals damaged or missing.
C.
Low line pressure (see Page 18).
D. Pump cover oil seal rings missing, broken or undersize;
ring groove oversize.
E. Case valve body face not flat or porosity between
channels.
2. INTERMEDIATE CLUTCH
A. Intermediate clutch piston seals damaged or missing.
B.
Low line pressure (see Page 18).
C. Case valve body face not flat or porosity between
channels.
3. DIRECT CLUTCH
A. Restricted orifice in vacuum line to modulator (poor
vacuum response).
B. Check ball in direct clutch piston damaged, stuck or
missing. (Some 1970 models. Refer to Service Manual)
C. Defective modulator bellows (see Page 21).
D. Clutch piston seals damaged or missing.
E. Case valve body face not flat or porosity between
NOTE: Burned clutch plates can be caused by incorrect
usage of clutch plates. Also, anti-freeze in transmission
fluid can cause severe damage, such as large pieces of
composition clutch plate material peeling off.
Checking Transmission Oil Level
1. Engine Running.
2.
Vehicle on level surface.
3.
Brakes applied.
4.
Move lever through all ranges.
5.
Place transmission in "PARK."
6.
Check oil level.
7.
If oil is low, check for possible causes - refer to page 14.
The oil level should be between the "Add" and "Full"
with the oil at approximately 70
°
F. (Room temperature.) If
the oil level is correctly established at room temperature
(70
°
F.), it should be at the "Full" mark on the dip stick when
the transmission reaches normal operating temperature
(180
°
F.).
CAUTION: DO NOT OVERFILL TRANSMISSION, AS
THIS WILL CAUSE FOAMING AND LOSS OF OIL
THROUGH THE VENT PIPE.
Manual Linkage Adjustment
The transmission manual linkage must be adjusted so that
the pointer on the indicator quadrant and linkage detents or
stops corresponds with the transmission inside detent lever
detents. If the linkage is not adjusted properly, an internal leak
could occur at the manual valve which could cause a clutch
and/or front band failure.
Refer to the Chevrolet Chassis Service Manual for manual
linkage adjustment procedure.
NOTE: If a manual linkage adjustment is made, the associ
ated neutral start switch should be adjusted, if necessary.
The neutral start switch should be adjusted so that the
engine will start in "PARK" and "NEUTRAL" positions
only, with the selector lever in the "PARK" position, the
parking pawl should freely engage and prevent the vehicle
from rolling.
Causes of Low Line Pressure
1.
Low Transmission oil level.
2.
Modulator Assembly - See Page 57.
3.
Screen Assembly
a.
Blocked or restricted.
b. Gasket between screen and valve body omitted or
damaged.
4. Pump
a. Gear clearance, damaged, worn (pump will become
damaged if drive gear is installed backwards, or if con
verter pilot does not enter crankshaft freely).
b.
Pump to case gasket mispositioned.
c.
Defective pump body and/or
cover.
5. Valve Body
a.
Pressure regulator or boost valve stuck.
b.
Pressure regulator spring, too weak.
6.
Internal Circuit Leaks
a. Forward clutch leak (pressure normal in neutral and
reverse-pressure low in drive).
Causes of High Line Pressure
1. Vacuum Leak
