1967 CHEVROLET CAMARO recommended oil

ENGINE-ELECTRICAL
6Y-21

Fig.
6i—Distributor Lead Arrangements

NOTE:
End of cam
lubricant wick should
be

adjusted
to
just touch
cam
lobes. Over lubrica-

tion
of cam
resulting
in
grease
on
contact points

can-
be
caused
by cam
lubrication wick bearing

too hard against
cam
surface.
A
correctly
ad-

justed
cam
lubricator wick will provide adequate

lubrication
for cam. Do not
apply additional

grease
to cam
surface.

7.
Start engine
and
check point dwell
and
ignition

timing.
ACTUAL
POINT OPENING
.021

.016
FEELER GAUGE

LOCATOR ___JH^H

(ROUND)
V~^3H|

CENTRIFUGAL
\
jdft

ADVANCE
-~-»JBlMBl

MECHANISM
«H

CAM g^k. / X

LUBRICATOR
V^^^

REPLACEMENT
^£9

^-ADJUST
SQUARELY

AND
JUST

TOUCHING
LOBE

OF
CAM
.ROTOR

I^^I^BL
LOCATOR

(PBV 7
(SQUARE)

SBSSF
/

WWjga^/
^/
LUBRICATOR

H^f
CAUTION!

S5y
NEVER
OIL

•-^
CAM
LUBRICATOR-

REPLACE
WICK

WHEN
NECESSARY
Fig.
8i—Inaccurate Gauging
of
Rough Points

SETTING DWELL ANGLE

Four
and Six
Cylinder Engine Distributors

The point opening
of new
points
can be
checked with
a

feeler gauge,
but the use of a
feeler gauge
on
rough
or

uncleaned used points
is not
recommended since accurate

mechanical gauging cannot
be
done
on
such points (fig. 8i).

Contact points must
be set to the
proper opening.

Points
set too
close
may
tend
to
burn and
pit
rapidly.

Points with excessive separation tend
to
cause
a
weak

spark
at
high speed. Proper point setting
for all

models
are:

.019"
for new
points

.016"
for
used points

New points must
be set to the
larger opening
as the

rubbing block will wear down slightly while seating
to the

cam. Contact points should
be
cleaned before adjusting
if

they have been
in
service.

LATERAL

MISALIGNMENT
PROPER

LATERAL
ALIGNMENT

pCORRECT
LATERAL MISALIGNMENT
BY

M
BENDING FIXED CONTACT SUPPORT

[NEVER
BEND BREAKER LEVER

Fig.
7i—Top View
of
Distributor

Fig.
9i—Alignment
of
Points

CHEVROLET
CHASSIS SERVICE /MANUAL

ENGINE-ELECTRICAL 6Y-28

terminals on eoil. On Corvettes equipped with radio,

remove bolts securing ignition shield over distribu-

tor and coil.

2.
Pull high tension wire from center terminal of coil.

3.
Remove the two coil support mounting bolts or loosen

friction clamp screw and remove coil.

4.
Place new coil in position and install attaching bolts

or tighten clamp screw.

5.
Place high tension lead securely in center terminal

of coil and connect ignition switch and distributor

primary leads to terminals on coil. Replace ignition

shield on Corvettes.

6. Start engine and test coil operation.

IGNITION PULSE AMPLIFIER

DISASSEMBLY

To check the amplifier for defective components, pro-

ceed as follows:

1.
Remove the bottom plate from the amplifier.

2.
To aid in reassembly, note the locations of the lead

connections to the panel board.

3.
Remove the three panel board attaching screws, and

lift the assembly from the housing.

4.
To aid in reassembly, note any identifying markings

on the two transistors and their respective locations

on the panel board and heat sink assembly.

5.
Note the insulators between the transistors.and the

heat sink, and the insulators separating the heat sink

from the panel board.

6. Remove the transistor attaching screws, and sepa-

rate the two transistors and heat sink from the panel

board.

7.
Carefully examine the panel board for evidence of

damage.

MOUNTING

SCREW

RESISTOR R5 jgSfe. / DIODE Dl

TRANSISTOR TR2

(UNDERNEATH)

1H L >©V

[So

To
I
/'%**jt\
\
TRANSISTC>R"""

1 X ^^w^ X \ (UNDERNEATH)

9^ESISTORR^^^H|^^^^^H

^B
RESISTOR
R4
^HPH^^H

WM'
RESISTOR
R3
I^B^^^^I^U

N .6 ®

mm

N%|/MOUNTING

• tr^i^w ^\ vjR SCREW

CAPACITOR
Cl\
pNkj^^A^
\
RESISTOR
Rl

MOUNTING ^55S^^ \ CAPACITOR C3

SCREW I RESISTOR R6 CAPACITOR C2

TRANSISTOR TR3
COMPONENT CHECKS (Figs. \7\ and 18i)

With the two transistors separated from the assembly,

an ohmmeter may be used to check the transistors and

components on the panel board for defects. An ohmmeter

having a 1-1/2 volt cell, which is the type usually found

in service stations, is recommended. The low range

scale on the ohmmeter should be used except where

specified otherwise.

A 25 watt soldering gun is recommended, and a 60% tin

40%
lead solder should be used when re-soldering. Avoid

excessive heat which may damage the panel board. Chip

away any epoxy involved, and apply new epoxy which is

commercially available.

In order to check the panel board assembly, it is

necessary to unsolder at the locations indicated in Fig-

ure 18i the two capacitors C2 and C3. In all of the fol-

lowing checks, connect the ohmmeter as shown and then

reverse the ohmmeter leads to obtain two readings. The

amplifier circuitry is shown in Figure 19i.

1.
Transistors TR1 and TR2: Check each transistor by

referring to Figure 20i. If both readings in Step 1

are zero, the transistor is shorted. If both readings

in Step 2 are zero, the transistor is shorted; and if

both readings are infinite, the transistor is open.

Interpret Step 3 the same as Step 2.

2.
Trigger Transistor TR3:
11
both readings in Step 1

are zero, the transistor is shorted. If both readings

in Step 2 are zero, the transistor is shorted; and if

both readings are infinite, the transistor is open.

Interpret Step 3 the same as Step 2.

3.
Diode Dl: 11 both readings are zero, the diode is

shorted; and if both readings are infinite, the diode

is open.

4.
Capacitor Cl: If both readings are zero, the capaci-

tor is shorted.

5.
Capacitors C2 and C3: Connect the ohmmeter across

CHECKING

RESISTOR Rl

UNSOLDER
I
CHECKING TRIGGER

TRANSISTOR TR3
CHECKING

CAPACITOR C

Fig.
171—Pulse Amplifier Panel Board
Fig.
18i—Pulse
Amplifier
Component
Checks

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH
AND
TRANSMISSIONS
7-23

Assembly (Fig.
4X)

1.
With detent spring tang projecting
up
over
the 3rd

and
4th
shifter shaft cover opening install
the
first

and second detent
cam
onto
the
detent
cam
pivot
pin.

With
the
detent spring tang projecting
up
over
the

first
and
second shifter shaft cover hole install
the

3rd
and 4th
detent
cam,

NOTE:
The 1-2
detent
cam has a
.090" greater

contour
on the
inside detent notch.

2.

3.
Install detent
cam
retaining
"C"
ring
to
pivot shaft,

and hook spring into detent
cam
notches.

Install
1-2 and 3-4
shifter shaft assemblies
in
cover

being careful
not to
damage seals. Install both shift

forks
to
shifter shaft assemblies, lifting
up on
detent
cam
to
allow forks
to
fully seat into position.

4.
Install reverse detent ball
and
spring
to
cover, then

install reverse shifter shaft assembly
to
cover.

5.
Install outer shifter levers, flat washers, lock wash-

ers
and
bolts.

Installation

1.
Shift shifter levers into neutral detent (center) posi-

tion. Position cover gasket
on
case.

2.
Carefully position side cover into place making sure

the shift forks
are
aligned with their respective

mainshaft clutch sliding sleeves.

Install cover attaching bolts
and
tighten evenly
to

specified torque.

Remove filler plug
and add
lubricant specified
in

Section
0, to
level
of
filler plug hole.
3.

4.

ALUMINUM POWERGLIDE

INDEX

Page

General
Description
7-23

Maintenance
and
Adjustments .............. 7—23

Oil
Level Check
7-23

Periodic
Oil
Change
7-24

Periodic
Low
Band Adjustment
7-24

Manual
Shift Linkage Check
and
Adjust
7-24

Floor
Shift Linkage
7-25

Floor
Mounted Control Lever
and

Bracket
Assembly
7-29

Throttle
Valve Linkage
.... 7-29

Neutral
Safety Switch
.. . 7-30

Throttle
Return Check Valve (Dashpot)
7-30

Component
Parts Replacement
7-30

Transmission
Replacement .............. 7—30
Page

Other
Service Operations
7-32

Diagnosis
7-32

Warming
Up
Transmission
7-32

Shop
Warm
Up , 7-32

Road
Warm
Up 7-32

Checking
Fluid Level
and
Condition
7-32

Manual
Linkage
7-32

Oil
Leaks
7-33

Basic
Pressure Checks
7-33

Wide
Open Throttle Upshift Pressure Check
.... 7-33

Idle
Pressure
in
Drive Range
7-33

Manual
"Low"
Range Pressure Check .......
7-33

Drive
Range Overrun (Coast) Pressure
.
.......
7-33

Powerglide
Shift Points
. . 7-35

GENERAL DESCRIPTION

The case
and
converter housing
of the two
speed alumi-

num Powerglide Transmission
is a
single case aluminum

unit. When
the
manual control
is
placed
in the
drive
po-

sition,
the
transmission automatically shifts
to low
gear

for initial vehicle movement.
As the car
gains speed
and

depending
on
load
and
throttle position,
an
automatic shift

is made
to
high gear.
A
forced downshift feature
pro-

vides
a
passing gear
by
returning
the
transmission
to low

range.

The
oil
pump assembly
is a
conventional gear type
and

the
oil
pump housing
is of the
large diameter type acting

as
the
front bulkhead
of the
transmission.
The
torque

converter
is a
conventional three element welded design

bolted
to the
engine flywheel which drives through
a
two-

speed planetary gearset.
The
high clutch assembly
is

typical
of the
designs used
in
this type transmission.
The

aluminum Powerglide uses
an
output shaft mounted
gov-
ernor which requires
a
hole through
the
output shaft.
The

reverse clutch assembly
is a
multiple disc type clutch.

The steel plates
are
splined directly
to the
case while
the

face plates
are
splined
to the
internal
or
ring gear.
The

clutch piston operates within
the
rear portion
of the
case.

The internal diameter
of the
pistoh
is
sealed to
an
integral

hub portion
of the
case rear bulkhead.
The
outside
dia-

meter
is
sealed
to a
machined portion
of the
case.
The

piston
is
hydraulically applied
and is
released
by
separate

coil springs.
The
valve body assembly
is
bolted
to the

bottom
of the
transmission case
and is
accessible
for

service
by
removing
the oil pan
assembly.
The
valve

body consists
of an
upper
and
lower body located
on
either

side
of a
transfer plate.
The
vacuum modulator
is lo-

cated
on the
left rear face
of the
transmission case.
The

modulator valve bore
is
located
in the
upper valve body.

MAINTENANCE
AND
ADJUSTMENTS

OIL LEVEL CHECK

The transmission
oil
level should
be
checked period-

ically
as
recommended
in
Section
0. Oil
should
be
added

only when level
is on or
below
the
"ADD" mark
on the dip

stick with
oil hot or at
operating temperature.
The oil

level
dip
stick
is
located
at the
right rear
of the
engine
compartment. Fill with
oil
specified
in
Section
0.

In order
to
check
oil
level accurately,
the
engine should

be idled with
the
transmission
oil hot and the
control

lever
in
neutral (N) position.

It
is
important that
the oil
level
be
maintained
no

higher than
the
"FULL" mark
on the
transmission
oil

level gauge.
DO NOT
OVERFILL,
for
when
the oil
level

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-24

is at the full mark on the dip stick, it is just slightly be-

low the planetary gear unit. If additional oil is added,

bringing the oil level above the full mark, the planetary

unit will run in the oil, foaming and aerating the oil. This

aerated oil carried through the various oil pressure pas-

sages (low servo, reverse servo, clutch apply, converter,

etc.) may cause malfunction of the transmission assem-

bly, resulting in cavitation noise in the converter and

improper band or clutch application. Overheating may

also occur.

If the transmission is found consistently low on oil, a

thorough inspection should be made to find and correct

all external oil leaks.

PERIODIC OIL CHANGE

The transmission oil should be changed periodically as

recommended in Section 0, and whenever transmission is

to be removed from the vehicle for repairs.

1.
Run engine for one minute in neutral prior to chang-

ing.

2.
Be sure vehicle is level or raise from the rear only.

3.
Remove the oil pan drain plug and allow oil to drain

thoroughly into a pan or can.

Replace drain plug and refill with approximately two

quarts of oil specified in Section 0.

NOTE: To refill the transmission, remove dip

stick from oil filler tube and refill transmission

with oil specified in Section 0 using filler tube

and funnel J-4264. Then, after shifting into all

ranges at idle speed to fill all oil passages, the

engine should be run at 800-1000 rpm with the

transmission in Neutral until the oil warms up,

then add oil as required to raise the fluid level

to the full mark on the dip stick. Refill capacity

is approximately 2 qts.
4.

Fig.
1PG - Adjusting Low Band Using J-21848
PERIODIC LOW BAND ADJUSTMENT (Fig. 1PG)

Low band adjustment should be periodically performed

at 12,000 mile intervals, or sooner, as necessary if op-

erating performance indicates low band slippage.

1.
Raise vehicle and place selector lever in neutral.

2.
Remove protective cap from transmission adjusting

screw.

3.
a. On Corvette Models: Drop left exhaust pipe for

clearance.

b.
On Chevelle Models: To gain clearance between

underbody and transmission, it may be necessary

to remove rear mount bolts from crossmember,

and move transmission slightly toward passenger

side of vehicle. .

4.
Loosen adjusting screw lock nut 1/4 turn and hold in

this position with wrench.

5.
Using Special Tool J-21848 adjust band to 70 in. lbs.

and back off four (4) complete turns for a band which

has been in operation for 6,000 miles or more,.or

three (3) turns for one in use less than 6,000 miles.

CAUTION: Be sure to hold the adjusting screw

lock nut at 1/4 turn loose with a wrench during"

the.adjusting procedure.

6. Tighten the adjusting screw lock nut to specified

torque.

CAUTION: The amount of back-off is not an

approximate figure, it must be exact.

MANUAL SHIFT LINKAGE CHECK & ADJUST

(Column Type)

1.
The shift tube and lever assembly must be free in the

mast jacket. See Section 9 for alignment of steering

column assembly if necessary.

2.
To check for proper shift linkage adjustment, lift

the transmission selector lever towards the steering

wheel. Allow the selector lever to be positioned in

drive (D) by the transmission detent.

NOTE: Do not use the indicator pointer as a

reference to position the selected lever. When

performing linkage adjustment, pointer is ad-

justed last.

3.
Release the selector lever. The lever should be in-

hibited from engaging low range unless the lever is

lifted.

4.
Lift the selector lever towards the steering wheel,

and allow the lever to be positioned in neutral (N) by

the transmission detent.

5.
Release the selector lever. The lever should now

be inhibited from engaging reverse range unless the

lever is lifted.

6. A properly adjusted linkage will prevent the selector

lever from moving beyond both the neutral detent, and

the drive detent unless the lever is lifted to pass

over the mechanical stop in the steering column.

7.
In the event that an adjustment is required, place

the selector lever in drive (D) position as determined

by the transmission detent. See Steps 2 and 3.

8. Loosen the adjustment swivel at the cross-shaft,

and rotate the transmission lever so that it contacts

the drive stop in the steering column.

9. Tighten the swivel and recheck the adjustment. See

2 and 6.

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-31

with the "white" stripe painted on the engine

side of the flywheel outer rim, denoting the

"heavy" side of the engine.

1.
Mount transmission on transmission lifting equip-

ment installed on jack or other lifting device.

2.
Remove converter holding tool.

CAUTION: Do not permit converter to move

forward after removal of holding tool.

3.
Raise transmission into place at rear of engine and

install transmission case to engine upper mounting

bolts,
then install remainder of the mounting*bolts.

Torque bolts to 35 ft. lbs.

4.
Remove support from beneath engine, then raise

rear of transmission to final position.

5. Through flywheel cover opening align as closely as

possible the "white" flywheel balance mark stripe

and the "blue" painted stripe on the end of converter

cover and housing. If scribed during removal, align

scribe marks on flywheel and converter cover. In-

stall converter to flywheel attaching bolts. Torque

bolts to 15-20 ft. lbs.

6. Install converter under pan.

7. Reinstall transmission support crossmember to

transmission and frame.

8. Remove transmission lift equipment.

9. Connect propeller shaft to transmissions.

10.
Connect manual and TV control lever rods to

transmission.

11.
Connect oil cooler lines (if so equipped), vacuum

Fig.
13PG - Converter Holding Tool
modulato:* line, and speedometer drive cable to

transmission.

12.
Refill transmission through filler tube, using Funnel

J-4264 and following the recommended procedure

provided earlier in this section.

13.
Check transmission for proper operation and for

leakage. Check and, if necessary, adjust linkage.

CORVETTE POWERGLIDE TRANSMISSION

Replacement

1.
Disconnect battery ground cable.

2.
Remove ball end from transmission shift control

lever.

3.
Raise front and rear of vehicle.

4.
Insert a block of wood between the top of the dif-

ferential carrier housing and the underbody (to

prevent upward travel of the carrier when the car-

rier front support is disconnected).

5. Disconnect the differential carrier front support

from its frame bracket, by removing the nut on the

underside of the biscuit mount.

6. Pry the carrier downward to relieve load while re-

moving the two center mounting bolts from the

carrier front support. (To pry carrier downward

insert crowfoot end of a pry bar**hrough the open-

ing in the carrier front support, hooking end of bar

over top of the center mounting bolt pad cast in the

underside of the carrier).

7. Pivot carrier support downward for access to prop

shaft "U"-joint.

8. Disconnect prop shaft front and then rear
"U"
bolts.

9. Disconnect parking brake cable from ball socket at

idler lever located near center of underbody.

10.
Remove prop shaft by moving shaft forward.

11.
Remove left bank exhaust pipe.

12.
Remove right bank exhaust pipe and heat riser.

13.
Disassemble the transmission mount, as follows:

a. Remove the two bolts that attach rear mount

cushion to the rear mount bracket.

b.
Support engine under oil pan and raise engine to

remove load from rear mount cushion.

CAUTION: To avoid damage to oil pan, a suit-

able wide base, heavy wood platform should be

placed between the jack pad and the oil pan.

c. Remove the three transmission mount bracket-

to-crossmember bolts, then remove mount

bracket.

d. Remove the two bolts from mount pad to trans-

mission case and remove rubber mount cushion

and exhaust pipe "yoke".

14.
Disconnect oil cooler lines at transmission and

swing lines clear.

15.
Remove connector underpan.

16.
Remove converter to flywheel attaching bolts.

17.
At transmission disconnect vacuum modulator line

and speedometer cable.

18.
Disconnect transmission shift linkage from trans-

mission gearshift control lever. Remove shift lever.

19.
At transmission, remove throttle valve linkage and

disconnect neutral safety switch linkage, also re-

move the gearshift control linkage.

20.
Remove neutral safety switch from transmission

control bracket.

CHEVROLET CHASSIS SERVICE

CLUTCH AND TRANSMISSIONS 7-32

21.
Remove transmission output shaft slip yoke and in-

sert a plastic shipping plug in end of extension to

prevent spillage of transmission fluid.

NOTE:
The yoke is removed to avoid tearing

the heat reflecting pad on the underbbdy, when

the transmission is being removed.

22.
Remove bright metal ignition shielding from dis-

tributor area.

23.
Remove the transmission dip stick and tube

assembly.

24.
Disconnect transmission vacuum modulator line at

distributor advance line tee.

25.
Position transmission hoist under transmission and

attach safety chain to transmission.

26.
Remove transmission converter housing-to-engine

attaching foolts and slide transmission rearward.
NOTE:
Observe converter when moving trans-

mission rearward. If converter does not move

with the transmission, pry it free of flywheel

before proceeding.

27.
Install converter retaining strap.

28.
Lower and remove transmission from vehicle by

tilting the front down and to the right while inter-

mittently lowering the transmission to facilitate its

• removal.

29.
Reinstall transmission assembly by performing the

above steps in reverse order.

Bolt Torques

Transmission Case to Flywheel

Housing Bolts 35 ft. lbs.

Converter to Flywheel Bolts. . , . . 35 ft. lbs.

OTHER SERVICE OPERATIONS

Although certain operations, such as oil pan or gasket

replacement, valve body, governor, filler pipe "O" ring,

speedometer drive gear, case extension "0" ring and

rear oil seal, vacuum modulator, and servo cover or

gasket service may be performed from underneath the
vehicle without removing the Powerglide; their service

procedure is covered in the Passenger Overhaul Manual

and is not repeated here. Refer to the- Powerglide Sec-

tion of the Passenger Overhaul Manual for all other

service operations not covered here.

DIAGNOSIS

Proper operation of the Powerglide transmission may

be affected by a number of factors, all of which must be

considered when trouble in the unit is diagnosed.

Proper trouble diagnosis can only be accomplished

when performed in a thorough step by step procedure.

The following procedure has been devised and tested and

is recommended for all trouble diagnosis complaints and

if the service man will follow this checking procedure,

accurate and dependable diagnosis may be accomplished.

This will result in a savings of time, not only to the

service man, but to the customer as well.

WARMING UP TRANSMISSION

Before attempting to check and/or correct any com-

plaints on the Powerglide transmission it is absolutely

essential that the oil level be checked and corrected if

necessary. An oil level which is either too high or too

low can be the cause of a number of abnormal conditions

from excessive noise to slippage in all ranges.

It must be remembered that cold oil will slow up the

action of the hydraulic controls in the transmission. For

this reason a trouble or oil leak diagnosis should not be

attempted until the transmission has been warmed up by

either of the following procedures:

Shop Warm Up

1.
Connect tachometer to engine.

2.
Set parking brake tight and start engine.

3.
Place selector light in
"D"
(drive) range.

4.
Adjust carburetor idle speed adjusting screw to run

engine at approximately 750 rpm and operate in this

manner for two minutes. At the end of two minutes

of operation, the transmission will be sufficiently

warmed up for diagnosis purposes.
NOTE:
At this point, readjust the engine idle

speed to 450-475 rpm in
"D"
range.

Road Warm Up

Drive the car approximately 5 miles with frequent

starts and stops.

NOTE:
At this point, make sure the engine idle

speed is set to 450-475 rpm in
"D"
range.

CHECKING FLUID LEVEL AND CONDITION

After transmission has been warmed up, check the

fluid level with the engine idling, parking brake set and

control lever in "N" (neutral). If the fluid level is low,

add fluid to bring level up to the full mark on gauge rod,

CAUTION: If fluid level is too high, fluid may

be aerated by the planet carrier. Aerated fluid

will cause turbulence in the converter which will

result in lost power, lower stall speed and lower

pressures in control circuits. Lower fluid level

to full mark, then shut off engine to allow air

bubbles to work out of fluid.

When checking oil level, aburned smell and discolora-

tion indicate burned clutches or bands and the transmis-

sion will have to be removed.

MANUAL LINKAGE

Manual linkage adjustment and the associated neutral

safety switch are important from a safety standpoint.

The neutral safety switch should be adjusted so that the

engine will start in the Park and Neutral positions only.

With the selector lever in the Park position, the park-

ing pawl should freely engage and prevent the vehicle

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-33

from rolling. The pointer on the indicator quadrant

should line up properly with the range indicators in all

ranges.

OIL LEAKS

Before attempting to correct an oil leak, the actual

source of the leak must be determined. In many cases

the source of the leak can be deceiving due to "wind flow1 f

around the engine and transmission.

The suspected area should be wiped clean of all oil

before inspecting for the source of the leak. Red dye is

used in the transmission oil at the assembly plant and

will indicate if the oil leak is from the transmission.

The use of a "black light"* to identify the oil at the

source of leak is also helpful. Comparing the oil from

the leak to that on the engine or transmission dip stick

(when viewed by black light) will determine the source

of the leak.

Oil leaks around the engine and transmission are gen-

erally carried toward the rear of the car by the air

stream. For example, a transmission "oil filter tube

to case leak" will sometimes appear as a leak at the

rear of the transmission. In determining the source of

an oil leak it is most helpful to keep the engine running.

The mating surfaces of servo cover, converter housing,

transmission case and transmission case extension

should be carefully examined for signs of leakage. The

vacuum modulator must also be checked to insure that

the diaphragm has not ruptured as this would allow trans-

mission oil to be drawn into the intake manifold. Us-

ually, the exhaust will be excessively smoky if the

diaphragm ruptures due to the transmission oil added to

the combustion. The transmission case extension rear

oil seal should also be checked. All test plugs should be

checked to make sure that they are tight and that there

is no sign of leakage at these points. The converter

underpan should also be removed. Any appreciable quan-

tity of oil in this area would indicate leakage at the pump

square seal ring, pump seal assembly, or pump bolt

sealing washers.

BASIC PRESSURE CHECKS

Four basic pressure checks are used for diagnosis and

operational checks for the Aluminum Powerglide trans-

mission. All checks should be made only after thoroughly

warming up the transmission.

• Wide Open Throttle Upshift Pressure.

• Idle Pressure in "Drive" Range.

• Manual "Low" Range Pressure.

• "Drive" Range Overrun (Coast) Pressure.

It is not recommended that stall tests be conducted

which would result in engine vacuum falling below 10" Hg.

Pressure gauge hose connections should be made at

the low servo apply (main line) test point (fig. 14PG).

Run the gauge line into the driving compartment by

pushing aside the mast jacket seal. The line out of the

way of the drivers feet and connect to pressure gauge

J-21867.

• Wide Open Throttle Upshift Pressure Check

Refer to the pressure check chart for upshift pressure
SERVO APPLY

PRESSURE

Fig.
14PG - Pressure Test Plug

points as indicated on the lower servo apply (main line)

gauge.

• Idle Pressure in "Drive" Range

In addition tp the oil pressure gauges, a vacuum gauge

is needed for this check.

With the parking brake applied and the shift selector

lever in "Drive", low servo apply (main line) pressure

should be as shown on the pressure check chart.

If pressures are not within these ranges, the following

items should be checked for oil circuit leakage:

1.
Pressure regulator valve stuck.

2.
Vacuum modulator valve stuck.

3.
Hydraulic modulator valve stuck.

4.
Leak at low servo piston ring (between ring and

bore).

5.
Leak at low servo piston rod (between rod and bore).

6. Leak at valve body to case gasket.

7.
Leak at valve body gaskets.

8. Front pump clearances.

9. Check passages in transmission case for porosity.

• Manual "Low" Range Pressure Check

Connect a tachometer, apply the parking brake, place

the selector lever in "Low" range, and adjust the engine

speed to 1000 rpm with the car stationary.

Low servo apply (main line) pressure should be as

shown on the pressure check chart.

Pressures not within this range can indicate the fol-

lowing possibilities:

1.
Partially plugged oil suction screen.

2.
Broken or damaged ring low servo.

CHEVROLET CHASSIS SERVICE MANUAL

WHEELS AND TIRES 10-4

the road and it slips, grinding off the tread on the inside

half of the tire at an excessive rate. This type of tire

shows much the same appearance of tread wear as tire

wear caused by negative camber.

Second, the transfer of weight may also over-load the

outside tires so much that they are laterally distorted

resulting in excessive wear on the outside half of the

tire producing a type of wear like that caused by ex-

cessive positive camber.

Cornering wear can be most easily distinguished from

abnormal camber wear by the rounding of the outside

shoulder or edge of the tire and by the roughening of the

tread surface which denotes abrasion.

Cornering wear often produces a fin or raised portion

along the inside edge of each row in the tread pattern.

In some cases this fin is almost as pronounced as a

toe-in fin, and in others, it tapers into a row of tread

blocks to such an extent that the tire has a definite step

wear appearance.

The only remedy for cornering wear is proper in-

struction of owners.

Fig.
5 - Tire Rotatidh

Rotation

To minimize the possibility of tire noise and to equal-

ize tire wear, it is recommended that tires be inter-

changed every 6000 miles as shown in Figure 5 or more

frequently in the case of extremely heavy wear.

NOTE:
Rotate Corvette tires at 4000 miles or

sooner.

Interchanging tires will effectively prevent undue wear

on any particular tire. II tire interchanging is followed

as recommended above, all tires will have the same

number of miles in each wheel position at the end of the

fourth change. When interchanging tires, inspect for

signs of abnormal wear, bulging, etc., stones, glass, and

nails should be removed before reinstallation.

Noise

Noise caused by the normal action of tire treads on

various road surfaces is often confused with rear axle
gears or other noises in the car.

The determination of whether tires are causing the

noise complained of is relatively simple. The car should

be driven at various speeds and note taken of part

throttle, and sudden acceleration and deceleration. Axle

and exhaust noises show definite variations under these

conditions, while tire noise will remain constant. Tire

noise is, however, most pronounced at speeds of approx-

imately twenty or thirty miles per hour.

The tires may be further checked by driving the ear

over smooth pavement with the tires at normal pressure

and again over the same stretch of pavement when the

tires have been inflated to fifty pounds pressure. Reduce

the tires to normal pressure one at a time to determine

the faulty tire or tires. This high inflation pressure

should immediately be reduced to normal after test. If

the noise for which the test is being made is caused by

tires,.
it will noticeably decrease when the tire pressure

is increased, whereas axle noise should show no change

in volume.

If, on inspection, the tires on the front wheels are

found to be creating most of the noise the alignment of

the front wheels should be checked. Excessive tire noise

usually results from lower than recommended tire pres-

sure, incorrect alignment, uneven tire wear, or defective

(thumper) tire.

Cleaning

A great deal of ordinary road dirt which collects on

white sidewall tires may be sponged off with clear water

or a mild soap solution.

A good brand of whitewall tire cleaner, however, is

a quicker and more effective cleaner for removing dirt

and stains from whitewall tires and in many cases it

will remove stains and discoloration that the simpler

method of soap and water will not remove.

Under no circumstances should gasoline, kerosene or

any cleaning fluid containing a solvent derived from oil

be used to clean whitewall tires. Oil in any form is

detrimental to tire rubber and a cleaner with an oil base

will discolor or injure whitewall tires.

Change (W/Wheels)

To change the road wheels using the jack that comes

with the car, observe the following procedure:

1.
Set hand brake and block front wheels if rear wheel

is being changed.

2.
Remove hub cap or wheel disc and break wheel

mounting nuts loose.

3.
Place the jack as directed tinder, General Informa-

tion,
Section 0 and raise car until wheel clears

ground.

4.
Remove wheel mounting nuts and remove wheel from

hub or drum.

5. To replace road wheel, reverse the above instrue-

. tions. Proper torque on nuts is 55-75 ft. lbs.

torque (70-85 ft. lbs. for Corvette aluminum wheel

nuts).

CAUTION: On models equipped with discs, in-

dex the pilot hole in the disc on the valve stem.

(To insure that the anti-rotation notches in wheel

disc register on lugs in wheel rim.)

CHEVROLET CHASSIS SERVICE MANUAL