CLUTCH AND TRANSMISSIONS 7-3
DETENT CAM
DETENT SPRING
DETENT CAM
2-3 SHIFT
FORK
DETENT CAM
PIVOT PIN
1ST & REV. 1ST& REV.
SHIFTER SHAFT SHIFT FORK
DETENT CAM
RETAINER RING
2-3 SHIFTER SHAFT
Fig. 3A
•*
Transmission Side Cover, Shift Fork and Detent Assembly
5. Reinstall propeller shaft and any items removed to
obtain clearance.
TRANSMISSION SIDE COVER
Removal •
1.
Disconnect control rods from levers; remove 2-3
cross shaft (Chevrolet)
2.
Shift transmission into neutral detent positions before
removing cover.
3.
Remove cover assembly from transmission case
carefully and allow oil to drain.
Disassembly (Fig. 3A)
1.
Remove the outer shifter levers.
2.
Remove both shift forks from shifter shaft assem-
blies.
Remove both shifter shaft assemblies from
cover. "OM ring seals around shifter shaft may now
be pryed out if replacement is required because of
damage.
3.
Remove detent cam spring and pivot retainer "C"
ring. Remove both detent cams.
4.
Replace damaged parts.
Assembly (Fig. 3A)
1.
With,
detent spring tang projecting up over the
2nd
and
3rd shifter shaft cover opening install the first and
reverse detent cam onto the detent cam pivot pin.
With the detent spring tang projecting up over the
first and reverse shifter shaft cover hole install the
2nd an£ 3rd detent cam.
2.
Install detent cam retaining "C" ring to pivot shaft,
and hook spring into detent cam notches.
3.
Install both 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 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.
3.
Install cover attaching bolts and tighten evenly to
specified torque.
4.
Remove filler plug and add lubricant specified in
Section 0, to level of filler plug hole.
COMPONENT PART REPLACEMENT
TRANSMISSION REPLACEMENT (EXC. CORVETTE)
Removal From Vehicle
1.
Remove propeller shaft assembly.
2.
Disconnect speedometer cable at transmission.
3.
Disconnect shifter rods at transmission levers.
4.
Support engine assembly.
5. Remove transmission to clutch housing bolts.
6. Remove transmission crossmember to mount bolts.
7. Loosen transmission crossmember and move rear-
ward or remove.
8. Slide transmission rearward and remove.
Installation in Vehicle
1.
Raise transmission into position and slide forward
piloting clutch gear retainer into clutch housing.
2.
Install transmission to clutch housing retaining bolts
and lock washers, torque to 50 ft. lbs.
3.
Repositioning transmission crossmember and install
retaining bolts.
4.
Install transmission crossmember to mount bolts.
5. Connect and adjust shift rods at transmission levers
and cordon shaft to 2nd and 3rd lever on Chevrolet
Models. (Fig. 4A)
Fig. 4A - Chevrolet 2-3 Shift Lever Cordon Shaft
CHEVROLET CHASSIS SERVICE MANUAL
CLUTCH AND TRANSMISSIONS 7-12
DIAGNOSIS-OVERDRIVE
MECHANICAL
Any one of the following general complaints may be due
to non-standard mechanical conditions in the overdrive
unit:
1.
Does not drive unless locked up manually.
2.
Does not engage, or lock-up does not release.
3.
Engages with a severe jolt, or noise.
4.
Free-wheels at speeds over 30 mph.
These^ troubles may be diagnosed and remedied as de-
scribed in the following paragraphs.
1.
Does not drive unless locked up manually.
a. Occasionally, the unit may not drive the car for-
ward in direct drive, unless locked up by pulling
the dash control. This may be caused by one or
more broken rollers in the roller clutch, the
remedy for which is the replacement of the entire
set of rollers.
b.
This may also be caused by sticking of the roller
retainer upon the cam. This retainer must move
freely to push the rollers into engaging position,
under the pressure of the two actuating springs.
c. Sometimes this is due to slight indentations, worn
in the cam faces by the rollers spinning, remedied
by replacement of the cam.
2.
Does not engage, or lock-up does not release
.. a. Dash control improperly connected—-Unless the
overdrive dash control wire is connected to the
lockup lever on the left side of the overdrive
housing in such a manner as to move the lever
all the way back when the dash control knob is
pushed in, it may hold the shift rail in such a po-
sition as to interlock the pawl against full engage-
ment resulting in a buzzing noise when overdrive
engagement is attempted.
To correctly make this connection, loosen bind-
ing post at lever, pull dash control knob out 1/4",
move lever all the way to the rear, and tighten
binding post.
b.
Transmission and overdrive improperly aligned—
The same symptoms as above may also result
from misalignment, at assembly, of the overdrive
housing to the transmission case, resulting in
binding of the overdrive shift rail, so that the re-
tractor spring cannot move the rail fully forward,
when the dash control knob is pushed in, and the
transmission is not in reverse. Under such con-
ditions, the unit may remain fully locked up.
To test for this, be sure that the transmission
is not in reverse; disconnect the dash control
wire from the lockup lever, and feel the lever for
free forward movement. If the lever can be
moved forward more than 1/4", it indicates that
misalignment probably exists. To correct this,
Jposen the capscrews between the overdrive hous-
ing and transmission case, and tap the adpater
plate and overdrive housing until a position is
found where the rail shifts freely; tighten cap-
screws.
c. Kickdown switch improperly adjusted—The posi-
tion of the kickdown switch should be adjusted,
by means of the two large nuts which clamp the
switch shank, so the switch plunger travels 3/16"
before the throttle lever touches its stop.
Occasionally the large nuts which clamp the
switch through the switch bracket are tightened
sufficiently to bend the switch shank, thus pre-
venting free motion of the switch stem. This may
usually be remedied by loosening the upper of the
two nuts.
d. Improper installation of solenoid—If car cannot
be rolled backward under any circumstances and
there is no relay click when the ignition is turned
on, it probably indicates that the solenoid has
been installed directly, without twisting into the
bayonet lock between solenoid stem and pawl, thus
jamming the pawl permanently into overdrive en-
gagement. If the car will occasionally roll back-
wards, but not always, (and there is no relay click
when the ignition switch is turned on) it may indi-
cate that, upon installation, the bayonet lock was
caught, and the solenoid forcibly twisted into
alignment with the attaching flange, thus shearing
off the internal keying of the solenoid. Under
these circumstances, the end of the solenoid stem
may not catch in the pawl, and upon release of the
solenoid, the pawl will not be withdrawn promptly
from engagement, but simply drift out. If the
solenoid stem end has its two flats exactly facing
the two solenoid flange holes, it will not withdraw
the pawl properly. If the stem can be rotated
when grasped by a pair of pliers, it indicates that
the internal keying has been sheared.
e. Improper positioning of blocker ring—Occasion-
ally, either in assembly at the factory, or in
service operations in the field, the internal parts
of the overdrive unit may have been rotated with
the solenoid pawl removed, causing the blocker
ring to rotate, so that its two lugs are not located
with respect to- the pawl as shown in Figure 12B.
In other words, the solid portion of the blocker
ring may be in alignment with the pawl, which will
prevent fill} engagement of the pawl with the sun
gear control plate/
To test for this condition, remove solenoid
cover, pull dash control knob out, roll car 2 ft.
forward. Push dash control in, turn ignition
switch on. Then ground the "KD" terminal of
relay, and watch movement of center stem of
solenoid. It should not move more than 1/8" when
the solenoid clicks. Then, with the relay terminal
still grounded, shift into low gear, and roll car
forward by hand. Solenoid stem should then move
an additional 3/8", as the pawl engages fully.
These two tests indicate proper blocker action.
Unless both tests are met, the blocker ring is
probably not in the correct position.
3.
Engages with a severe jolt or noise
Insufficient blocker ring friction may cause the ring
to lose its grip on the hub of the sun gear control
plate. Check the fit and tension of the ring as de-
scribed under "Cleaning and Inspection".
4.
Free-wheels at speeds over 30 MPH
If cam roller retainer spring tension is weak the unit
will free wheel at all times. Check spring action as
described under "Cleaning and Inspection".
CHEVROLET CHASSIS SERVICE MANUAL
CLUTCH AND TRANSMISSIONS 7-19
2.
With handle in full down position—adjust cable to ac-
quire dimension shown, be certain that cable is pulled
taut.
3.
Tighten set screw to 15-20 in. lbs.
4.
Bend excess wire and cut - be certain that wire does
not interfere with I.D. of lever or threads of shifter
knob.
NOTE: Handle must return freely from any
position.
SPEEDOMETER DRIVEN GEAR AND OIL SEAL
Replacement
Disconnect speedometer cable, remove retainer to
housing bolt and lock washer and remove retainer. In-
sert screw driver in slot in fitting and pry fitting, gear
and shaft from housing. Pry "O" ring in groove in fitting.
Install new "O" ring in groove and insert shaft Hold
the assembly so slot in fitting is toward boss on housing
and install in housing. Push fitting into housing until re-
tainer can be inserted in groove and install retainer lock
washer and bolt.
Fig.
5M - Installing Side Cover Assembly
TRANSMISSION SIDE COVER
Removal
1.
Disconnect control rods from levers.
2.
Shift transmission into second speed before removing
cover, by moving 1-2 (Rear Cover) shifter lever into
forward detent position.
3.
Remove cover assembly -from transmission case
carefully and allow oil to drain.
Disassembly (Fig. 4M)
1.
Remove the outer shifter lever nuts,*lock washers
and flat washers. Pull levers from shafts.
2.
Remove both shift forks from shifter shaft and detent
plate assemblies. Remove both shifter shaft assem-
blies from cover. Lip seals in side cover may now
be pryed out if replacement is required because of
damage.
1-2 DETENT CAM DETENT SPRING
3-4 DETENT CAM
1-2 SHIFTER SHAFT
1-2 SHIFT FORK
3-4 SHIFT
FORK
DETENT CAM \ 3-4 SHIFTER SHAFT
RETAINER RING
DETENT CAM PIVOT PIN
3.
Remove detent cam spring and pivot retainer "C"
ring. Remove both detent cams.
4.
Replace necessary parts.
Assembly (Fig. 4M)
1.
Install 1-2 detent cam to cover pivot pin first, then
install 3-4 detent cam so the detent spring notches
are offset or opposite each other. Detent cam
notches must be facing downward.
2.
Install detent cam retaining "C" ring to pivot shaft,
and hook spring into detent cam notches.
3.
Install both shifter shaft assemblies in cover being
careful not to damage lip seals. Install both shift
forks to detent plates, lifting up on detent cam to
allow forks to fully seat into position.
4.
Install outer shifter levers, flat washers, lock wash-
ers and nuts.
Installation (Fig. 5M)
1.
Shift 1-2 shifter lever into second speed (forward)
position. 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.
3.
Install cover attaching bolts and tighten evenly to
15-20 ft. lbs. torque.
4.
Remove filler plug and add lubricant specified in
Section 0, to level of filler plug hole.
EXTENSION OIL SEAL
Replacement
1.
Remove propeller shaft.
2.
Pry out the extension oil seal.
3.
Prelubricate between sealing lips and press new oil
seal carefully into place in extension using J-5154 or
similar tool.
Fig.
4M - Transmission Side Cover/ Shift Fork and
Detent Assembly
CAUTION: Do not excessively force the seal
against the seat in the extension.
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
FUEL TANK AND EXHAUST SYSTEMS 8-20
4.
Attach the retaining straps with strap guide attached
to the fuel tank support, and secure with-the nut and
lockwasher assembly.
5. Connect the filler neck boot to the drain hose of the
tank and install boot around filler neck,
6. Connect the fuel pickup line, ground wire and make
certain that the fuel drain line is flush to 1/2" in-
board of the rear bumper opening.
7. Attach tank metering unit wires (fig. 25).
8. Replace fuel in tank. Replace gas cap.
9. Check for possible leaks.
10.
Reconnect the exhaust system by reversing the above
removal procedures (see "Exhaust System").
11.
Install spare tire carrier by securing the bolt
attachment.
12.
Install the spare tire in the tire carrier.
Removal (36 Gallon Tank)
1.
Remove cover (fig. 26).
2.
Disconnect hoses and drain tank and remove two
fittings at bottom of tank.
3.
Disconnect fuel and vent lines and wires at tank
(fig. 27).
4.
Remove straps.
installation (36 Gallon Tank)
Reverse removal procedure to install.
FUEL TANK METERING UNIT OR GAUGE
SENDING UNIT AND STRAINER
The fuel tank metering unit is located at the bottom of
the fuel tank. The fuel strainer is attached at the end of
the sending unit inside the tank.
Replacement (20 Gallon Tank)
1.
Follow fuel tank removal procedure through Step 2.
2.
Drain the tank. Disconnect the attaching wires.
3.
Remove metering unit with a fuel tank gauge unit
Spanner J-8950 (revised).
4.
'Remove metering unit and gasket.
CAUTION: Carefully remove unit so as not to
damage screen on the end of the pipe.
5. Clean strainer screen by blowing out with com-
pressed air.
6. Reverse procedure to install.
Replacement (36 Gallon Tank)
1.
Remove cover.
2.
Follow Steps 2 thru 6 as outlined under replacement
for 20 gallon tank.
FUEL LINES
20 Gallon Tank
The fuel lines are conveniently located along the out-
side of the right frame rail (fig. 28). The lines extend
Fig.
26—Gasoline Tank (36 Gallon) Compartment Cover
from the fuel tank pickup at the bottom of the tank, along
the rear frame crossmember to the right frame rail,
extending through the rail at the kickup area and along the
top inside edge of the frame to the fuel pump, Flexible
hoses are located at the fuel tank pickup and at the fuel
pump.
36 Gallon Tank
The 36 gallon tank fuel lines are routed from the bot-
tom of both sides of the tank to the right frame rail
(fig. 20).
Maintenance
CAUTION: Always drain gasoline from the
complete fuel system including carburetor, fuel
pump and all fuel lines and fuel tank if the vehi-
cle is to be stored for any great length of time.
This precaution will prevent accumulation~ol
gum formation and resultant poor engine
performance.
. The fuel lines should occasionally be inspected for
leaks,
kinks or dents, especially when work has been
done on the underside of car or after the car has been
traveling over rough or stone roads at higher speeds.
If evidence of dirt is found in the carburetor or fuel pump
at disassembly, the lines should be disconnected and
blown put. Check the fuel tank strainer for damage or
omission.
Fuel lines are beaded-type ends for connection to
hoses and flared ends for secure metal-to-metal line
connections.
CHEVROLET CHASSIS SERVICE MANUAL
SECTION 10
WHEELS AND TIRES
INDEX
Page
General Description
10-1
Maintenance
and
Adjustments
.............. 10—1
Tires
10-1
Pressures . 10-1
Inspection 10-1
Wear 10-1
Rotation 10-4
Noise 10-4
Cleaning 10-4
Change (W/Wheels) 10-4
Wheels 10-5
Static Balancing (w/Tire) 10-5
Page
Dynamic Balancing (w/Tire) . 10-5
Run Out (w/o Tire) 10-5
Cleaning 10-5
Service Operations 10-5
Tires 10-5
Removal 10-5
Installation 10-5
Repair 10^6
Wheels . 10-6
Valve Assembly 10-6
Repair (Rim) 10-7
GENERAL DESCRIPTION
WHEELS
Chevrolet, Chevelle, Camaro, Chevy n, and Corvette
are base equipped with welded steel wheels. Five studs
with nuts fasten each wheel to the front hub or rear axle
flange. Disc brake equipped vehicles (except Chevrolet
and Corvette) require special 14 inch diameter wheels
with a revised design for clearance, Chevrolet disc brake
equipped vehicles have 15 in. diameter wheels as do all
Corvettes.
Chevrolet station wagons, Chevelle Super Sport 396,
Corvette and Camaro Super Sport 350 are base equipped
with 6 in. width wheels. All other vehicles have 5 in.
width wheels, except Chevy n 100, 300 and 500 Series
Sedans, which have 4 in. width wheels.
Do not install 6 inch width wheels or snow chains on
Chevrolets equipped with rear fender skirts.
TIRES
The factory installed tires on Chevrolet passenger
cars are selected to provide the best all around tire
performance for all normal operation. They are de-
signed to operate satisfactorily with loads up to and in-
cluding the specified full rated load capacity of the
automobile when inflated as recommended in the Vehicle
Capacity Rating and Recommended Tire Inflation Pres-
sures Table (see Specifications).
Optional Oversize and 8-Ply Rating Tires
{Chevrolet and Chevelle Only)
Oversize or 8-ply rating tires are not necessary on
passenger cars for normal requirements. However, an
extra margin of tire service is available when these
options are used at loads up to and including full rated
load.
Optional oversize 4-ply rating and/or 8-ply rating
tires are available on models as indicated in the Tire
Usage Chart (see Specifications). On some models (ex-
ample—Station Wagon), space limitations do not permit
the use of a larger size tire; hence, the 8-ply rating
tire is an available option.
In either case, these tires are applicable to extended
operation at or near full rated load or for trailer towing
when an extra margin of tire service is desired. How-
ever, use of a larger tire or an 8-ply rating tire should
not be construed as permitting an increase in the full
rated vehicle load (see Specifications).
MAINTENANCE AND ADJUSTMENTS
TIRES
Inflation Pressures
To ensure the proper tire inflation pressure for the
owners particular requirements follow the recommenda-
tions in the Vehicle Capacity Rating and Recommended
Tire Inflation Pressures Table (seeSpecifications). Keep
tires properly inflated, and check inflation pressures
periodically. This will ensure the best tire life and riding
comfort, over the full range of driving conditions.
Inspection
Every few thousand miles and at each lubrication, tires
should be checked for sharp objects or stones in the
tread. H tire is punctured, it should be repaired using
one of several repair kits available through tire manu-
facturers1 outlets.
Wear
Misalignment
This is wear due to excessive toe-in or toe-out. In
CHEVROLET CHASSIS SERVICE MANUAL
WHEELS AND TIRES 10-5
WHEELS
The wheel and tire assembly should be removed from
vehicles equipped with disc brakes to properly perform
balancing operations. This is necessary due to drag of
the spring loaded brake shoes on the disc.
Static Balancing (W/Tire)
Static Balance (still balance) is the equal distribution
of weight of the wheel and tire assembly about the axis
of rotation so that the assembly has no tendency to rotate
by
itself.
Static unbalance causes the pounding action of
the front wheels that is called "tramp".
To correct static unbalance (front and rear): The
quickest and best methods to correct static unbalance
are through the use of wheel balancers which are com-
mercially available. Refer to the Information and in-
structions included with these balaricers.
Dynamic Balancing (W/Tire)
Dynamic Balance (running balance) requires the wheel
to be not only in static balance, but balanced and running
smoothly while turning on an axis which runs through the
centerline of the wheel and tire perpendicular to the axis
of rotation.
The quickest and best methods of testing and correcting
dynamic unbalance are by the use of dynamic wheel
balancers which are commercially available. These bal-
ancers include all necessary information on where and
how the balancing weights should be placed. The follow-
ing information, however, will help in the correction of
dynamic balance.
NOTE:
Before attempting to balance the
wheels, check to be certain that no foreign
matter has been trapped in the wheel ventila-
tion slots or in the accessory wheel discs. This
is especially important if the vehicle has been
run in soft mud and then parked in freezing
weather.
When a wheel that is statically unbalanced is dynam-
ically in balance the dynamic balance can be retained
while correcting "the static balance by installing the cor-
rective weights so that half of the weight required is
placed on the inner edge of the rim and the other half
on the outer edge of the rim.
Dynamic unbalance can be corrected without destroying
static balance by installing weights so half of weight
required for dynamic balance is placed on the rim op-
posite the heavy point, while the other half is placed 180°
away and on the opposite side of the rim.
NOTE:
Vehicles with wire wheel covers should
have the wheels balanced with the wire wheel
covers installed on the wheels.
Run Out (W/OTire)
The wheels should not run out (wobble) more than
1/16" as measured on the side of the rim at the base
of the tire. Excessive run-out is the result of a bent
wheel, an improperly mounted wheel, worn knuckle bear-
ings or steering connections. These parts should be
checked for correct adjustment, proper alignment and
wear whenever excessive run-out is encountered.
The wheels should also run concentric with the steering
knuckle spindle within 1/16 inch as measured on the tire
bead seat of the rim with the tire removed.
Wheel run-out, eccentricity and balance are closely
associated with steering and front wheel alignment.
Further information on these subjects will be found under
"Suspension".
Cleaning Aluminum Wheels
Do not use wire brush or abrasive cleaners when
cleaning wheels. Use only cleaners that will not react
with aluminum.
SERVICE OPERATIONS
TIRES
Removal
Dismounting tubeless tires presents no problems if the
correct procedures are used and the following precau-
tions observed.
1.
Remove the valve cap and valve core. Let out all the
air.
2.
Press the inner side of the tire into the rim well.
Use bead loosening tool or if regular tire irons are
used, take particular care not to injure or tear the
sealing ribs on the bead.
CAUTION: Never use tire irons with sharp
edges or corners.
3.
Using tire irons on the opposite side, remove bead,
taking small "bites" around the rim.
4.
Turn the tire over, and use two tire irons, one be-
tween the rim flange and the bead to pry the rim
upward, the other iron to pry outward between the
bead seat and the bead.
Installation
Extreme care must be exercised to prevent injury to
the sealing bead and circumferential bead when forcing
tire over rim.
1.
Apply a light film of Ruglyde or other suitable rubber
lubricant to sealing bead of tire.
NOTE:
The use of excessive lubrication may
lead to rim slippage and subsequent breaking of
air seal.
2.
Carefully mount the outer bead in usual manner by
using tire irons, taking small "bites" around rim,
being careful not to injure the tire bead.
CAUTION: DO NOT use a hammer, as damage
to the bead will result.
3.
Install the inner bead in the same manner.
NOTE:
If a seal cannot be effected in the fore-
going manner with the rush of air it can be
, accomplished by applying to the circumference
of the tire a tire mounting band or heavy sash
cord and tightening with the use of a tire iron.
On tire mounting machines, bouncing the tire
assembly is not required. The tire should be
CHEVROLET CHASSIS SERVICE MANUAL
WHEELS AND TIRES
10-6
lifted on the rim to force the top tire bead
against the top rim flange. The weight of the
tire will seat the bottom bead.
Repair
When a tire loses all or most of its air pressure,
particularly when driving at high legal speeds on today1 s
super-highways, recommended procedure is to remove it
from the wheel for complete inspection to be sure no
tire damage has occurred. Punctured tires should be
removed from the wheel and permanently repaired from
the inside.
Externally applied plug type repairs should be con-?
sidered temporary and the tire should be permanently
repaired as soon as possible.
Hot Patch Method
It is essential to thoroughly clean and remove all
foreign matter from the hole left by the puncturing-object
without enlarging the injury and then follow the manu-
facturer's instructions for vulcanizing the patch.
Rubber Plug Methods
There are several types of rubber plugs--some are
inserted from the inside of the tire; others are inserted
from the outside of the tire without demounting the tire
from the rim.
When using the plug method be sure to clean and
lubricate the hole with repair cement before inserting
the plug. Your tire supplier has available complete kits
containing materials, tools and detailed instructions for
making repairs with plugs. Follow instructions in the kit
you use.
Cold Patch Method
(Self Vulcanizing Type)
In this method it is essential to thoroughly clean and
remove all foreign matter from the hole left by the
puncturing object without enlarging the injury; also on
the inside of the tire, buff an area large enough for the
patch. Follow the manufacturer1 s instructions for appli-
cation of the special cement and self-vulcanizing cold
patch.
Pressure Gun Method
Several types of pressure guns are available. Consult
your tire supplier for materials and instructions.
Tire Installation Safety Precautions
When tires are mounted on dirty or corroded rims, or
when they are not properly centered on rims, the tire
bead may "bind" on the rim, and refuse to seat. Allowing
pressure to continue to build up within the assembly in
an attempt to seat the tire bead is a DANGEROUS PRAC-
TICE which can result in a broken tire bead, and serious
injury to the serviceman.
1.
Make sure that rim flanges and bead ledge (espe-
cially hump and radius) areas are smooth and clean.
Remove any oxidized rubber, dried soap solution,
rust, heavy paint, etc. with a wire brush, or, in ex-
treme cases, a file.
2.
Lubricate tire beads, rim flanges, and bead ledge
areas with a liberal amount of thin vegetable oil
soap solution, or approved rubber lubricant,
3.
Insure that air pressure build-up during the bead
seating process is not allowed to exceed 40 pounds
pressure. If beads have not seated by the time pres-
sure reaches 40 pounds, assembly should be deflated,
re-positioned on rim, re-lubricated and re-inflated.
4.
Make sure valve core is inserted in valve stem
prior to inflating.
5.
Use an extension gauge with clip on chuck so air
pressure build-up can be closely watched and so
that you can stand well back from the assembly
during the bead seating process.
WHEELS
Valve Assembly
Replace
NOTE: Always use new valve assembly when
replacing.
1.
Cut or drive old valve assembly out of rim.
2.
Clean valve hole and surrounding area on inside of
flange with steel wool.
Fig. 6 - Installing Valve
Fig. 7 - Rim Inspection
CHEVROLET CHASSIS SERVICE MANUAL