1967 CHEVROLET CAMARO fluid rear

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 7-32

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 7-36

TURBO HYDRA-MATIC TRANSMISSION

INDEX

Page

General Description . . , . 7-36

Maintenance and Adjustments . 7-37

Transmission Fluid 7-37

Fluid Level Indicator 7-37

Shift Control Linkage Adjustment ........... 7-37

Neutral Safety Switch Adjustment 7-37

Draining and Refilling Transmission . . . 7-37

Pressure Regulator Valve 7-38

Control Valve Body . 7-39

Governor ..'.... 7-40

Modulator and Modulator Valve 7-40

Parking Linkage . . 7-40
Page

Rear Seal -. 7-40

Other Service Operations . . 7-40

Transmission Replacement 7-40

Turbo Hydra-Matic Diagnosis Procedure. ......... 7-41

Sequence . ; ; 7-41

Oil Level and Condition Check 7-41

Manual Linkage 7-41

Oil Leaks .' 7-41

Case Porosity - Repair ................ 7-42

Oil Pressure Check 7-42

Transmission Shift Points 7-42

Special Tools 7-43

GENERAL DESCRIPTION

The Turbo Hydra-Matic transmission is a fully auto-

matic unit consisting primarily of a 3-element hydraulic

torque converter and a compound planetary gear set.

Three multiple-disc clutches, one sprag unit, one roller

clutch and two bands provide the friction elements re-

quired to obtain the desired function of the compound

planetary gear set.

The torque converter couples the engine to the plane-

tary gears through oil and provides hydraulic torque

multiplication when required. The compound planetary

gear set produces three forward speeds and reverse.

The
3-
element torque converter consists of a pump or

driving member, a turbine or driven member, and a

stator assembly. The stator is mounted on a one-way

roller clutch which will allow the stator to turn clock-

wise but not counter-clockwise.

The torque converter housing is filled with oil and

is attached to the engine crankshaft by a flex plate and

always rotates at engine speed. The converter pump is

an integral part of the converter housing, therefore the

pump blades, rotating at engine speed, set the oil within

the converter into motion and direct it to the turbine,

causing the turbine to rotate.

As the oil passes through the turbine it is traveling in

such a direction that if it were not re-directed by the

stator it would hit the rear of the converter pump blades

and impede its pumping action. So at low turbine speeds,

the oil is re-directed by the stator to the converter pump

in such a manner that it actually assists the converter

pump to deliver power or multiply engine torque.

As turbine speed increases, the direction of the oil

leaving the turbine changes and flows against the rear

side of the stator vanes in a clockwise direction. Since

the stator is now impeding the smooth flow of oil, its

roller clutch releases and it revolves freely on its shaft.

Once the stator becomes inactive, there is no further

multiplication of engine torque within the converter. At

this point, the converter is merely acting as a fluid

coupling as both the converter pump and turbine are

being driven at approximately the same speed - or at a

one-to-one ratio.

A hydraulic system pressurized by a gear type pump

provides the working pressure required to operate the

friction elements and automatic controls.

External control connections to transmission are:
Manual Linkage

Engine Vacuum

12 Volt Electrical

Signal
To select the desired op-

erating range.

To operate a vacuum mod-

ulator unit.

To operate an electrical

detent solenoid.

A vacuum modulator is used to automatically sense

any change in the torque input to the transmission. The

vacuum, modulator transmits this signal to the pressure

regulator for line pressure control, to the 1-2 accumula-

tor valve, and to the shift valves so that all torque re-

quirements of the transmission are met and smooth

shifts are obtained at all throttle openings.

The detent solenoid is activated by an alectric switch

on the carburetor. When the throttle is fully opened, the

switch on the carburetor is closed, activating the detent

solenoid and. causing the transmission to downshift at

speeds below approximately 70 MPH.

The selector quadrant has six selector positions: P,R,

N,D,
L2,L1.

P.
*
- Park position positively locks the output shaft to

the transmission case by means of a locking pawl

to prevent the vehicle from rolling in either di-

rection. The engine may be started in Park

position.

R. - Reverse enables the vehicle to be operated in a

reverse direction.

N.
- Neutral position enables the engine to be started

and run without driving the vehicle.

D,
- Drive Range is used for all normal driving condi-

tions and maximum economy. Drive Range has

three gear ratios, from the starting ratio to

direct drive. Detent downshifts are available by

depressing the accelerator to the floor.

L2.
- L2 Range has the same starting ratio as Drive

Range, but prevents the transmission from shift-

ing above second speed to retain second speed

acceleration when extra performance is desired.

L2 Range can also be used for engine braking.

L2 Range can be selected at any vehicle speed,

and the transmission will shift to second gear and

remain in second until the vehicle speed or the

throttle are changed to obtain first gear operation

in the same manner as in D Range.

CHIVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-37

LI.
- LI Range can be selected at any vehicle speed,

and the transmission will shift to second gear

and remain in second until vehicle speed is re-

duced to approximately 40 MPH, .depending on

axle ratio. LI Range position prevents the trans-

mission from shifting out of first gear.
It is very important that any communication concerning

the Turbo Hydra-Matic always contain the transmission

serial number and that all transmission parts returned

to Chevrolet Motor Division always be tagged with the

transmission serial number.

MAINTENANCE AND ADJUSTMENTS

TRANSMISSION FLUID

Transmission fluid level should be checked with trans-

mission warm and selector lever in "P" Park position,

every time engine oil level is checked or as specified in

Section 0 when engine oil is changed.

CAUTION: Since the Turbo Hydra-Matic trans-

mission is very sensitive to oil level, special

precautions should be taken when checking the

oil level, to insure against an overfifE

Transmission fluid should be changed as specified in

Section 0.

FLUID LEVEL INDICATOR

The fluid level indicator is located in the filler pipe at

the right rear corner of the engine. To bring the fluid

level from the add mark to the full mark add 1 pint.

Fluid level should be to the full mark with transmission

at normal operating temperature. With cold fluid the

level should be at the add mark or slightly below.

SHIFT CONTROL LINKAGE ADJUSTMENT

Adjust linkage as shown below and in Figure 2.

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 selector 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.

See schematic diagram.

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

Steps 2 and 6. -

l(h Readjust indicator needle if necessary to agree with

the transmission detent" positions. See Section 9.

11.
Readjust neutral safety switch if necessary to pro-

vide the correct relationship to the transmission de-

tent positions. See Section 12.

12.
When properly adjusted the following conditions must

be met by manual operation of the steering column

shift lever:

a. From reverse to drive position travel, the trans-

mission detent feel must be noted and related to

indicated position on dial.

b.
When in drive and reverse positions, pull lever

rearward (towards steering wheel) and then re-

lease. It must drop back into position with no

restrictions.

NEUTRAL SAFETY SWITCH ADJUSTMENT

The neutral safety switch must be adjusted so that the

car will start in the park or neutral position, but will not

start in the other positions. For replacement refer to

Section 12 of this Manual.

DRAINING AND REFILLING TRANSMISSION

Drain oil immediately after operation before it has had

an opportunity to cool.

To drain oil proceed as follows:

1.
Remove bottom pan attaching screws, pan, and gas-

ket.

2.
Remove oil strainer. Remove "O" ring seal from

pick-up pipe and discard.

3.
Discard strainer if dirty.

4.
Install new "O" ring seal on pick-up pipe and install

strainer and pipe assembly.

5.
Thoroughly clean bottom pan.

6.. Affix new gasket to bottom pan with petroleum jelly.

7.
Install bottom pan with attaching screws and torque

to specifications;

8. If only the pan has been removed, pour approximately

7-1/2 pints of fluid into the transmission. If the

valve body has also been removed use 9-1/2 pints.

After a complete overhaul approximately 19 pints

are required. Be sure container, spout, or funnel is

clean.

9. Start engine and let idle (carburetor off fast idle

step).
Place selector lever in P position and apply

hand brake.

10.
With transmission warm (approximately 150°F), add

fluid to bring level to full mark on indicator.

CAUTION: Do not overfill. Foaming will re-

sult.

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-41

CAUTION: Use converter holding ToolJ-5384

when lowering transmission or keep rear of

transmission lower than front so as not to lose
converter.

The installation of the transmission is the reverse of

the removal.

TURBO HYDRA-MATIC DIAGNOSIS PROCEDURE

Accurate diagnosis of transmission problems begins

with a thorough understanding of normal transmission

operation. In particular, knowing which units are in-

volved in the various speeds or shifts so that the specific

units or circuits involved in the problem can be isolated

and investigated further. Analytical diagnosis will pro-

tect the technician from come backs and certainly will

improve owner satisfaction.

An important and often overlooked aspect of diagnosis

is finding out specifically what the customer is com-

plaining of. For this purpose a short ride with the cus-

tomer will often prove beneficial. It may be found that

the condition the customer wants corrected is standard

and should not be altered.

The following sequence, based on field experience, pro-

vides the desired information quickly and in most cases

actually corrects the malfunction without requiring the

removal of the transmission. Details of the items listed

in this sequence are covered further in the text.

SEQUENCE FOR TURBO HYDRA-MATIC

DIAGNOSIS PROCEDURE

1.
Check oil level and condition.

2.
Check and correct detent switch.

3.
Check and correct vacuum line and fittings.

4.
Check and correct manual linkage.

OIL LEVEL AND CONDITION CHECK

Always check the oil level before road testing. Oil

must be visible on dip stick prior to operating the ve-

hicle. Erratic shifting, pump noise, or other malfunc-

tions can in some cases be traced to improper oil level.

Oil level should be checked with the selector lever in

the Park (P) position, engine running, and the vehicle on

level pavement.

Fluid level should be to the FULL mark with the trans-

mission at normal operating temperature (170°-190°
F.).

With warm fluid (room temperature), the level should be

at or slightly below the ADD mark.

If oil level was low, refer to Oil Leaks.

The condition of the oil is often an indication of whether

the transmission should be removed from the vehicle, or

to make further tests. When checking oil level, a burned

smell and discoloration indicate burned clutches or bands

and the transmission 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

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 flow"

around the engine and transmission.

The suspected area should be wiped clean of all oil be-

fore 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 filler 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.

POSSIBLE POINTS OF OIL LEAKS

• 1. TRANSMISSION OIL PAN LEAK

a. Attaching bolts not correctly torqued.

b.
Improperly installed or damaged pan gasket.

c. Oil pan gasket mounting face not flat.

2.
REAR EXTENSION LEAK

a. Attaching bolts not correctly torqued.

b.
Rear seal assembly — damaged or improperly

installed.

c. Gasket seal — (extension to case) damaged or

improperly installed.

d. Porous casting.

3.
CASE LEAK

a. Filler pipe "O" ring seal damaged or missing;

misposition of filler pipe bracket to engine —

"loading" one side of
"O"
ring.

b.
Modulator assembly "O" ring seal
—
damaged or

improperly installed.

c. Governor cover, gasket and bolts — damaged,

loose; case face leak.

d. Speedo gear
—
"O" ring damaged.

e. Manual shaft seal — damaged, improperly in-

stalled.

f. line pressure tap plug — stripped, shy sealer

compound.

g. Parking pawl shaft cup plug
—
damaged, improp-

erly installed.

h. Vent pipe (refer to Item 5).

i. Porous case.

4.
FRONT END LEAK

a. Front seal - damaged (check converter neck for

nicks,
etc., also for pump bushing moved for-

ward);
garter spring missing from pump to con-

verter seaL

b.
Pump attaching bolts and seals
—
damaged, miss-

ing, bolts loose.

CHEVROLET a
SERVICE

STEERING 9-34

Fig.
64-Over Center Adjustment

transmission fluid "Type A" bearing the mark

"AQ-ATF" followed by a number and the suffix

letter "A".

ADJUSTMENTS

POWER STEERING GEAR

Chevrolet, Chevelle, and Camaro

The over-center adjustment (fig. 64) is the only power

steering gear adjustment which can be made on the car.

However, in order to make this adjustment, it is also

necessary to check the combined ball and thrust bearing

preload.

If the vehicle is equipped with a tilt column it will be

necessary to disconnect the steering coupling to obtain a

torque reading of the column. This torque should then be

subtracted from any reading taken on the gear.

1.
Disconnect the pitman arm from the relay rod.

2.
Loosen the pitman shaft adjusting screw loeknut and

thread the adjusting screw out to the limit of its

travel through the side cover. '. •

3.
Disconnect steering column harness at chassis wir-

ing connector plug.

4.
Remove horn button.

5.
Turn the steering wheel through its full travel, then

locate the wheel at its center of travel.

6. Gheck the combined ball and thrust bearing preload

with an inch-pound torque wrench on the steering

shaft nut by rotating through the center of travel

(approximately 1/4 turn in each direction). Note the

highest reading.

7.
Tighten the pitman shaft adjusting screw and check

torque at steering shaft nut until over center preload

and total steering gear preload falls within speci-

fications. Refer to torque specifications at rear of

manual for correct torque values.

8. Install horn button. Connect steering column harness

at wiring connector plug.
Chevy II and Corvette

The steering gear used with power steering is adjusted

in the same manner as the manual steering gear.

PUMP BELT TENSION

1.
Loosen nut on pivot bolt and pump brace adjusting

nut.

CAUTION: Do not move pump by prying against

reservoir or by pulling on filler neck.

2.
Move pump, with belt in place until belt is tensioned

to specifications as indicated by Tool J-7316 (Fig-.

65).

3.
Tighten pump brace adjusting nut. Then tighten pivot

bolt nut.

HYDRAULIC SYSTEM CHECKS

The following procedure outlines methods to identify

and isolate power steering hydraulic circuit difficulties.

This test is divided into two parts. Test number one

provides means of determining whether power steering

system hydraulic parts are actually faulty. If test number

one results in readings indicating faulty hydraulic opera-

tion, test number two will identify the faulty part. Be-

fore performing hydraulic circuit test, carefully check

belt tension and condition of driving pulley. Strand

tension of belt should be 125 lbs. on new belts and 75 lbs.

on old belts, as indicated by Tool J-7316 (Fig. 65).

Test Number One—Oil Circuit Open

Engine must be at normal operating temperature. In-

flate front, tires to correct pressure. All tests are made

with engine idling, so adjust engine idle speed to correct

specifications listed in Section 6 and proceed as follows:

a. With engine not running, disconnect flexible pres-

sure line from pump and install Tool J-5176 as

Fig.
65— Checking Belt Tension with Tool J-7316

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