clutch CHEVROLET DYNASTY 1993 Manual Online

Unless the condition is obvious, like no drive in D
range first gear only. The transaxle should never be
disassembled until hydraulic pressure tests have
been performed.
HYDRAULIC PRESSURE TESTS
Pressure testing is a very important step in the di-
agnostic procedure. These tests usually reveal the
cause of most transaxle problems. Before performing pressure tests, be certain that
fluid level and condition, and control cable adjust-
ments have been checked and approved. Fluid must be at operating temperature (150 to 200
degrees F.). Install an engine tachometer, raise vehicle on hoist
which allows front wheels to turn, and position ta-
chometer so it can be read. Disconnect throttle cable and shift cable from tran-
saxle levers so they can be controlled from outside
the vehicle. Attach 150 psi gauges to ports required for test be-
ing conducted. A 300 psi gauge (C-3293) is required
for reverse pressure test at rear servo.
Test port locations are shown in (Fig. 3).
TEST ONE (SELECTOR IN 1)
(1) Attach gauges to lineandlow-reverse ports
(Fig. 3). (2) Operate engine at 1000 rpm for test.
(3) Move selector lever on transaxle all the way
rearward ( 1position).
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position. (5) Line pressure should read 52 to 58 psi with
throttle lever clockwise and gradually increase, as le-
ver is moved counterclockwise, to 80 to 88 psi. (6) Low-reverse pressure should read the same as
line pressure within 3 psi. (7) This tests pump output, pressure regulation,
and condition of rear clutch and rear servo hydraulic
circuits.
TEST TWO (SELECTOR IN 2)
(1) Attach one gauge to line pressureport and
tee another gauge into lower cooler line fitting. This
will allow you to read lubricationpressure (Fig 3).
(2) Operate engine at 1000 rpm for test.
Fig. 3 Transaxle (Left Side)
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(3) Move selector lever on transaxle one detent
forward from full rearward position. This is selector
2 position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position. (5) Line pressure should read 52 to 58 psi with
throttle lever clockwise and gradually increase, as le-
ver is moved counterclockwise, to 80 to 88 psi. (6) Lubrication pressure should be 10 to 25 psi
with lever clockwise and 10 to 35 psi with lever full
counterclockwise. (7) This tests pump output, pressure regulation,
and condition of rear clutch and lubrication hydrau-
lic circuits.
TEST THREE (SELECTOR IN D)
(1) Attach gauges to lineandkickdown release
ports (Fig. 3). (2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle two detents
forward from full rearward position. This is selector
D position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position. (5) Line pressure should read 52 to 58 psi with
throttle lever clockwise and gradually increase, as le-
ver is moved counterclockwise to 80 to 88 psi. (6) Kickdown release is pressurized only in direct
drive and should be same as line pressure within 3
psi, up to kickdown point. (7) This tests pump output, pressure regulation,
and condition of rear clutch, front clutch, and hy-
draulic circuits.
TEST FOUR (SELECTOR IN REVERSE)
(1) Attach 300 psi gauge to low-reverseport (Fig.
3). (2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle four detents
forward from full rearward position. This is selector
R position.
(4) Low-reverse pressure should read 180 to 220
psi with throttle lever clockwise and gradually in-
crease, as lever is moved counterclockwise to 260 to
300 psi. (5) This tests pump output, pressure regulation,
and condition of front clutch and rear servo hydraulic
circuits. (6) Move selector lever on transaxle to Dposition
to check that low-reverse pressure drops to zero. (7) This tests for leakage into rear servo, due to
case porosity, which can cause reverse band burn
out.
TEST RESULT INDICATIONS
(1) If proper line pressure, minimum to maximum, is
found in any one test, the pump and pressure regulator
are working properly. (2) Low pressure in D, 1, and 2but correct pressure
in Rindicates rear clutch circuit leakage.
(3) Low pressure in D and Rbut correct pressure in
1 indicates front clutch circuit leakage.
(4) Low pressure in R and 1but correct pressure in
2 indicates rear servo circuit leakage.
(5) Low line pressure in all positions indicates a
defective pump, a clogged filter, or a stuck pressure
regulator valve.
GOVERNOR PRESSURE
Test only if transaxle shifts at wrong vehicle speeds
when throttle cable is correctly adjusted. (1) Connect a 0-150 psi pressure gauge to governor
pressure take-off point, located at lower right side of
case, below differential cover (Fig. 3). (2) Operate transaxle in third gear to read pres-
sures. The governor pressure should respond smoothly
to changes in mph and should return to 0 to 3 psi when vehicle is stopped. High pressure at
standstill (above 3 psi) will prevent the transaxle from
downshifting.
THROTTLE PRESSURE
No gauge port is provided for throttle pressure.
Incorrect throttle pressure should only be suspected if
part throttle upshift speeds are either delayed or occur
too early, with a correctly adjusted throttle cable.
Engine runaway on either upshifts or downshifts can
also be an indicator of incorrect (low) throttle pressure
setting, or misadjusted throttle cable. In no case should throttle pressure be adjusted until
the transaxle throttle cable adjustment has been veri-
fied to be correct.
CLUTCH AND SERVO AIR PRESSURE TESTS
A no drive condition might exist even with correct
fluid pressure, because of inoperative clutches or
bands. The inoperative units, clutches, bands, and
servos can be located through a series of tests by
substituting air pressure for fluid pressure (Fig. 4). The front and rear clutches, kickdown servo, and
low-reverse servo may be tested by applying air pres-
sure to their respective passages after the valve body assembly has been removed. To make
air pressure tests, proceed as follows: Compressed air supply must be free of all dirt
or moisture. Use a pressure of 30 psi. Remove oil pan and valve body See Disassembly-
Subassembly Removal .
FRONT CLUTCH
Apply air pressure to front clutch applypassage and
listen for a dull thudwhich indicates that front
Ä TRANSAXLE 21 - 43

clutch is operating. Hold air pressure on for a few
seconds and inspect system for excessive oil leaks.
REAR CLUTCH
Apply air pressure to rear clutch applypassage
and listen for a dull thudwhich indicates that rear
clutch is operating. Also inspect for excessive oil
leaks. If a dull thudcannot be heard in the clutches,
place finger tips on clutch housing and again apply
air pressure. Movement of piston can be felt as the
clutch is applied.
KICKDOWN SERVO (FRONT)
Direct air pressure into kickdown servo ONpas-
sage. Operation of servo is indicated by a tightening
of front band. Spring tension on servo piston should
release the band.
LOW AND REVERSE SERVO (REAR)
Direct air pressure into LOW-REVERSE SERVO
APPLY passage. Operation of servo is indicated by a
tightening of rear band. Spring tension on servo pis-
ton should release the band. If clutches and servos operate properly, no upshift
or erratic shift conditions indicate that malfunctions
exist in the valve body.
FLUID LEAKAGE-TRANSAXLE TORQUE
CONVERTER HOUSING AREA
(1) Check for Source of Leakage.
Since fluid leakage at or around the torque con-
verter area may originate from an engine oil leak,
the area should be examined closely. Factory fill
fluid is dyed red and, therefore, can be distinguished
from engine oil. (2) Prior to removing the transaxle, perform the
following checks:
² When leakage is determined to originate from the
transaxle, check fluid level prior to removal of the
transaxle and torque converter.
² High oil level can result in oil leakage out the
vent in the dipstick. If the fluid level is high, adjust
to proper level. After performing this operation, inspect for leak-
age. If a leak persists, perform the following opera-
tion on the vehicle to determine if it is the torque
converter or transaxle that is leaking.
LEAKAGE TEST PROBE
(1) Remove torque converter housing dust shield.
(2) Clean the inside of torque converter housing
(lower area) as dry as possible. A solvent spray fol-
lowed by compressed air drying is preferable.
Fig. 4 Air Pressure Tests
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If equipped, unplug torque converter clutch
plug, located near the dipstick.
CAUTION: Raise vehicle. Remove front wheels. Refer
to Suspension, Group 2 to remove or install wheel
hub nut and both drive shafts. Remove torque converter dust cover. Mark
torque converter and drive plate with chalk, for
reassembly. Remove torque converter mounting
bolts.
Fig. 1 Remove Upper and Lower Oil Cooler Hoses
Fig. 2 Engine Support Fixture
Fig. 3 Remove Bell Housing Upper Bolts
Fig. 4 Remove or Install Left Splash Shield
Fig. 5 Remove or Install Access Plug in Right Splash Shield to Rotate Engine Crankshaft
Fig. 6 Remove or Install Wire to Neutral/Park Safety Switch
Ä TRANSAXLE 21 - 49

CAUTION: The input shaft for transaxles without a
torque converter clutch has 2 seal rings. The input
shaft for a transaxle with a torque converter clutch
has three seal rings.
Fig. 15 Loosen Kickdown Band Adjusting Screw
Fig. 16 Kickdown Band and Strut
Fig. 17 Front Clutch Assembly
Fig. 18 No. 2 Thrust Washer and Rear Clutch
Fig. 19 No. 3 Thrust Washer
Fig. 20 Front Planetary Gear Snap Ring
21 - 54 TRANSAXLE Ä

Fig. 27 No. 10 Thrust Washer
Fig. 28 Overrunning Clutch Cam Assembly
Fig. 29 Overrunning Clutch Rollers and Springs
Fig. 30 Loosen or Adjust Low-Reverse Band
Fig. 31 Low-Reverse Band and Strut
Fig. 32 No. 11 Thrust Washer
21 - 56 TRANSAXLE Ä

All subassemblies should be inspected and/or recon-
ditioned when transaxle recondition is performed. Re-
fer to appropriate subassembly in this section for
recondition procedure.
ASSEMBLY SUBASSEMBLY INSTALLATION
When rebuilding, reverse the above procedure.
VALVE BODY-RECONDITION
Tighten all valve body screws to 5 Newton-
meters (40 in.lbs.) Do not clamp any portion of valve body or transfer
plate in a vise. Any slight distortion of the aluminum
body or transfer plate will result in sticking valves,
excessive leakage or both. When removing or in-
stalling valves or plugs, slide them in or out
carefully. Do not use force. TAG ALL SPRINGS AS THEY ARE REMOVED
FOR REASSEMBLY IDENTIFICATION.
CLEANING AND INSPECTION
Allow all parts to soak a few minutes in a suitable
clean solvent. Wash thoroughly and blow dry with
compressed air. Make sure all passages are clean and
free from obstructions. Inspect manual and throttle valve operating levers
and shafts for being bent, worn or loose. If a lever is
loose on its shaft, it should be replaced. Do not attempt
to straighten bent levers. Inspect all mating surfaces for burrs, nicks and
scratches. Minor blemishes may be removed with cro-
cus cloth, using only a very light pressure. Using a
straightedge, inspect all mating surfaces for warpage
or distortion. Slight distortion may be corrected, using
a surface plate. Make sure all metering holes in steel
plate are open. Using a pen light, inspect bores in valve
body for scores, scratches, pits and irregularities. Inspect all valve springs for distortion and col-
lapsed coils. Inspect all valves and plugs for burrs,
nicks, and scores. Small nicks and scores may be re-
moved with crocus cloth, providing extreme care is
taken not to round off sharp edges. The sharpness of
these edges is important. They prevent foreign mat-
ter from lodging between valve and valve body, thus
reducing possibility of sticking. Inspect all valves
and plugs for freedom of operation in valve body
bores. When bores, valves, and plugs are clean and dry,
the valves and plugs should fall freely in the bores.
The valve body bores do not change dimensions with
use. Therefore, a valve body that was functioning
properly when vehicle was new, will operate cor-
rectly if it is properly and thoroughly cleaned. There
is no need to replace valve body unless it is damaged
in handling.
Fig. 1 Detent Spring Attaching Screw and Spring
Fig. 2 Remove Valve Body Screws
Fig. 33 Install Overrunning Clutch Rollers and Springs
Ä TRANSAXLE 21 - 57

OIL PUMP-RECONDITION
Also, check gear side clearance with a straight
edge and a feeler gauge (See Specifications).
FRONT CLUTCH-RECONDITION
INSPECTION
Inspect plates and discs for flatness. They must not
be warped or cone shaped. Inspect facing material on all driving discs. Re-
place discs that are charred, glazed or heavily pitted.
Discs should also be replaced if they show evidence of
material flaking off or if facing material can be
scraped off easily. Inspect driving disc splines for
wear or other damage. Inspect steel plate surfaces for
burning, scoring, or damaged driving lugs. Replace if
necessary. Inspect steel plate lug grooves in clutch retainer
for smooth surfaces, plates must travel freely in
grooves. Inspect band contacting surface on clutch re-
tainer for scores, the contact surface should be pro-
tected from damage during disassembly and
handling. Note ball check in clutch retainer, make
sure ball moves freely. Inspect piston seal surfaces in
clutch retainer for nicks or deep scratches, light
scratches will not interfere with sealing of seals. In-
spect clutch retainer inner bore surface for wear from
reaction shaft support seal rings. Inspect clutch re-
tainer bushing for wear or scores. Inspect inside bore of piston for score marks, if
light, remove with crocus cloth. Inspect seal grooves
for nicks and burrs. Inspect seals for deterioration,
wear, and hardness. Inspect piston spring, retainer
and snap ring for distortion.
Fig. 4 Measuring Pump Clearance (Gear to Pocket)
Fig. 1 Reaction Shaft Support Bolts
Fig. 2 Reaction Shaft Support
Fig. 3 Inner and Outer Pump Gears
21 - 62 TRANSAXLE Ä

DISASSEMBLE/ASSEMBLE
To reassemble, reverse the above procedure.
MEASURING PLATE CLEARANCE
Fig. 1 Front Clutch Waved Snap Ring
Fig. 2 Thick Steel Plate and Waved Snap Ring
Fig. 3 Front ClutchÐThree-Disc Shown
Fig. 4 Front Clutch Return Spring Snap Ring
Fig. 5 Front Clutch Return Spring and Piston
Fig. 6 Measuring Front Clutch Plate Clearance
Ä TRANSAXLE 21 - 63

REAR CLUTCH-RECONDITION
INSPECTION
Inspect facing material on all driving discs. Re-
place discs that are charred, glazed or heavily pitted.
Discs should also be replaced if they show evidence of
material flaking off or if facing material can be
scraped off easily. Inspect driving disc splines for
wear or other damage. Inspect steel plate and pres-
sure plate surface for burning, scoring or damaged
driving lugs. Re place if necessary. Inspect plates and
discs for flatness, they must not be warped or cone-
shaped. Inspect steel plate lug grooves in clutch retainer
for smooth surfaces, plates must travel freely in the
grooves. Note ball check in piston; make sure ball
moves freely. Inspect seal rings surfaces in clutch re-
tainer for nicks or deep scratches; light scratches will
not interfere with sealing of the seals. Inspect neo-
prene seal rings for deterioration, wear and hard-
ness. Inspect piston spring and waved snap ring for
distortion or breakage. Inspect teflon and/or cast iron seal rings on input
shaft for wear. Do not remove rings unless conditions
warrant. Inspect rear clutch to front clutch No. 2
thrust washer for wear. Washer thickness should be
.061 to .063 inch, replace if necessary.
DISASSEMBLE/ASSEMBLE
Fig. 1 Rear Clutch Outer Snap Ring
Fig. 2 Rear ClutchÐThree-Disc Shown
Fig. 3 Piston Spring Waved Snap Ring
Fig. 4 Rear Clutch Piston and Piston Spring
21 - 64 TRANSAXLE Ä