SECTION 6r

ENGINE - DIAPHRAGM CLUTCH

CONTENTS OF THIS SECTION

General Description
Operation

General Description

The clutch used on all 6 cylinder standard transmission models and on V-8's equipped with the 2-barrel carburetor, is a single plate dry disc type consisting of two basic assemblies, the driven disc and facing assembly and the cover, pressure plate and diaphragm spring assembly. See figure 1 for a cross section of the clutch.

The cover and pressure plate assembly is bolted directly to the flywheel. The driven disc assembly is splined to the clutch gear. The pressure plate forces the disc against the flywheel (when engaged) providing the drive between the flywheel and transmission clutch gear. The driven disc assembly, which includes a hub and torsional springs, has conventional clutch facing riveted on both sides of the disc.

The pressure plate and diaphragm spring are assembled in the clutch cover and mounted to the flywheel over the driven disc assembly. The pressure plate is driven through three equally spaced double spring steel straps, riveted to the cover which is bolted to the engine flywheel, and bolted to the pressure plate. The diaphragm spring is dished to maintain a constant pressure on the pressure plate which in turn holds the driven disc in contact with the flywheel face. This spring has eighteen tapered fingers pointing inward and is made from very high quality steel, carefully heat treated and shot blasted to provide long life. The action of this diaphragm spring can be compared to the flexing action of the bottom of an ordinary oil can. By depressing the clutch pedal, the throwout bearing is forced against the diaphragm spring fingers causing the diaphragm spring to pivot on pivot rings, (fig. 2).

An oil impregnate type pilot bearing is installed in the end of the crankshaft and serves as a pilot for the transmission clutch gear. The release bearing, which is a part of the clutch release collar and bearing assembly, is a sealed ball type. The release fork is ball stud mounted in the clutch housing, the inner end of the fork engaging the grooves in the release collar for actuating the collar and bearing. A spring on the fork is provided to take up clearance between the fork and collar groove.

The clutch pedal is of the suspended type, providing maximum toe space in the driver's leg room area and reducing noise and fume sealing problems. A compensating type of linkage is used to connect the pedal arm to the clutch release fork. The compensating action is provided by a bell crank, ball-mounted at one end to the engine and ball mounted at the other end to the frame. A clutch pedal arm link attaches to a lever at the frame end of the bell crank. The lever at the engine end of the bell crank is connected to the clutch release fork. With this design, engine vibrations and movements are not transmitted to the clutch pedal or will not bring about a change in length of the linkage system.

Operation

The clutch is always engaged unless purposely disengaged by the driver by depressing the foot pedal. In the engaged position, the diaphragm spring fingers are flat and the entire rim of the spring exerts pressure against the pressure plate (fig. 3).

When the clutch pedal is depressed, pressure of the throwout bearing on the inner ends of the diaphragm fingers causes a diaphragm action and the outer ends of the fingers, near the rim, pivot on the inner pivot ring. This action causes the rim of the diaphragm spring and the pressure plate to move away from the clutch disc, disengaging the clutch (fig. 4). When the clutch pedal is released and the throwout bearing no longer contacts the fingers, the spring in the diaphragm causes the fingers to pivot about the rear pivot ring and the rim to bear against the pressure plate. Pedal overhaul operations are covered in section 5 of this manual.

Care, Maintenance and Adjustments

Clutch Pedal Free Travel
Clutch Retracting Springs

There is only one adjusting point on the clutch linkage. This will compensate for all normal clutch wear.

Clutch Pedal Free Travel

The pedal should travel 3/4" to 1" before the bearing engages the spring. This may be checked by moving the pedal with the hand to feel the free travel area and measuring the movement.

NOTE: Make this check by hand and not by foot as this feel is sensitive.

1. Remove cotter pin, washer and spring "1" (fig. 5).
2. Turn adjusting block "2" ( fig. 5) until free pedal travel is 3/4" to 1". (One turn equals approximately 3/16" at pedal.)
3. Reinstall spring, washer, and cotter pin.

A rattle in the clutch assembly at idling speeds with the clutch released may be caused by insufficient tension on the pressure plate retracting springs. This noise can easily be remedied by replacing the springs, as follows:

1. Remove the clutch housing underpan.
2. Crank the engine until one retracting spring attaching bolt is at the bottom. Remove the bolt and retracting spring and install a new spring.
3. Replace the other retracting springs in the same manner.
4. Replace clutch housing underpan.

Major Service Operations
Removal
Disassembly
Inspection, Repairs Pilot Bearing
Assembly

Major Service Operations

There are many things which affect good clutch operation. Therefore, it is necessary, before performing any major clutch operations, to make certain preliminary inspections to determine whether or not the trouble is actually in the clutch.

1. Check the clutch pedal and make sure that the pedal has 3/4" to if' free travel before the clutch starts to disengage. NOTE: It is very important to ascertain that the free travel felt is the true lash and not lash due to looseness in the pedal linkage. To check this, grasp the clutch pedal push rod with the hand and hold it firmly to prevent movement. Check for lash feel at the pedal. If any is felt, it is probably looseness at the upset joint between the pedal and its shaft, or the pedal shaft lever is not properly tightened on the serrations of the shaft. This looseness must be corrected before free travel is set.
2. Check the clutch pedal bushing for sticking on the shaft or loose mountings.
3. Lubricate the pedal linkage and overcenter spring ends.
4. Tighten all front and rear engine mounting bolts. Should the mountings be oil soaked, it will be necessary to replace them.
5. Check clutch bell crank between engine and frame for sticking or looseness.
6. Also, check for excessive end play due to a worn or compressed condition of the felt washers.
7. Check for proper pedal height. The top of the clutch pedal pad should be at least 7" ( 1/4" ) above the deadener felt glued on the metal floor pan (not the floor mat) to provide proper pedal travel for release. If less than this, cut off rubber bumper stop to obtain proper pedal height. Proper pedal travel is 7 3/8" (total) measured as chord of are traveled by pedal pad.

1. Remove transmission as outlined in "Transmission Section."
2. Remove clutch throwout bearing from the fork.
3. Remove clutch fork tension spring from fork. Disconnect clutch fork push rod.
4. Remove clutch fork by forcing it forward and toward the center of the vehicle.
5. Install Tool 5824 to support the clutch assembly during removal.
6. Loosen the clutch attaching bolts one turn at a time until diaphragm spring is released.
7. Remove Clutch Pilot Tool and remove clutch assembly from vehicle.

1. Remove three drive-strap to pressure plate bolts (fig. 6) and retracting springs and remove pressure plate from clutch cover. NOTE: When disassembling, note position of grooves on edge of pressure plate and cover. These marks must be aligned in assembly to maintain balance.
2. The clutch diaphragm spring and two pivot rings are riveted to the clutch cover. Spring, rings and cover should be inspected for excessive wear or damage and if there is a defect, it is necessary to replace the complete cover assembly.

Inspection

1. Wash all parts, except throwout bearing in cleaning solvent. NOTE: The throwout bearing is permanently packed with lubricant and should not be soaked in cleaning solvent as this may dissolve the lubricant.
2. Inspect pressure plate and flywheel for scores on the contact surfaces.
3. Check drive-straps for looseness at the clutch cover rivets and evidence of looseness at pressure plate bolt holes.
4. Check throwout bearing for roughness and free fit on the sleeve of the transmission clutch gear bearing retainer.
5. Inspect clutch disc for worn, loose or oil soaked facings, broken springs, loose rivets or riding.
6. Examine splines in hub and make sure they slide freely on splines of transmission clutch shaft. If splines are worn, the clutch disc or clutch gear should be replaced as necessary.

Repairs

Pilot Bearing

The clutch pilot bearing is an oil impregnated type bearing pressed into the crankshaft. This bearing requires attention only when the clutch is removed from the vehicle, at which time it should be cleaned and inspected for excessive wear or damage and should be replaced if necessary. To remove, install Tool 1448 and remove bearing from crankshaft (fig. 7). In replacing this bearing, use Tool 1522. Place bearing on pilot of tool with radius in bore of bearing next to shoulder on tool and drive into crankshaft

Assembly

1. Install the pressure plate in the cover assembly, lining up the groove on the edge of the pressure plate with the groove on the edge of the cover.
2. Install pressure plate retracting springs and drive strap to pressure plate bolts and lockwashers and tighten to 11 ft. lbs. torque. The clutch is now ready to be installed.
3. Hand crank the engine until "X" mark on flywheel is at the bottom.
4. Install clutch disc, pressure plate and cover assembly and support them with clutch pilot tool.
5. Turn clutch assembly until "X" mark on clutch cover flange lines up with "X" mark on flywheel. Align nearest bolt holes in clutch and in flywheel.
6. Install bolts in 3 holes marked "L" in cover assembly first and pull down gradually until tight. Then install remaining 3 bolts.
7. Remove clutch pilot.
8. Pack clutch fork ball seat with a small amount of high melting point grease.
9. Replace clutch fork on the clutch fork ball in clutch housing.
10. Lubricate the recess on the inside of the throwout bearing collar and coat the throwout fork groove with a small amount of graphite grease (fig. 8). CAUTION: Be careful not to use too much lubricant.
11. Install throwout bearing assembly to the throwout fork and hook up linkage.
12. Install transmission as outlined in Transmission Section.

DIAPHRAGM CLUTCH

Symptom and Probable Cause
Probable Remedy

Slipping

a. Improper adjustment.
a. Adjust pedal travel.

b. Oil soaked.
b. Install new disc.

c. Worn splines on clutch gear.
c. Replace transmission clutch gear.

d. Lining torn loose from disc.
d. Install new disc.

e. Warped pressure plate or flywheel.
e. Replace pressure ate or flywheel.


Grabbing

a. Oil on lining.
a. Install new disc.

b. Worn splines on clutch gear.
b. Replace transmission clutch gear.

c. Loose engine mountings.
c. Tighten or replace mountings.

d. Warped pressure plate or flywheel.
d. Replace pressure plate or flywheel.


Rattling

a. Weak retracting springs.
a. Replace springs.

b. Throwout fork loose on ball stud or in bearing groove.
b. Check ball stud and retaining spring and replace if necessary.


Noisy

a. Worn throwout bearing.
a. Replace bearing.


Pedal Height, Tension

a. Pedal low, clutch lever not contacting rubber stop bumper.
a. Pedal return is preset, however it can be modified somewhat by cutting off both
clutch and brake pedal bumpers.

b. Pedal low, clutch lever compressing rubber stop bumper.
b. Pedal return is preset, however it can be modified somewhat by cutting off both
clutch and brake pedal bumpers.

c. Pedal high.
c. Pedal return is preset, however it can be modified somewhat by cutting off both
clutch and brake pedal bumpers.

d. Lack of free pedal travel feel.
d. Pedal return is preset, however it can be modified somewhat by cutting off both
clutch and brake pedal bumpers.

Diaphragm Clutch Specifications

Type - Single Plate Dry Disc
Disc Diameter-V-8 - 10"
-Line 6 - 9 1/2"
Clutch Pressure Spring
Type - Diaphragm
Diameter - 91"
Clutch Release Bearing
Type - Sealed Ball
Make - New Departure
Clutch Pilot Bearing
Type - Oil Impregnated Bushing
Clutch Pedal
Pedal Pressure - 4 to 9 Pounds To Start Pedal Movement

General Description

The clutch used on all V-8 engines equipped with Power Package is a semi-centrifugal, coil spring single plate dry disc type. In this design, pressure plate load increases with engine speed giving a greater capacity at high speed. This centrifugal action is provided by three roller assemblies built into the pressure plate. There is no adjustment for wear provided for in the clutch itself, as in some other types of clutches. An individual adjustment is provided for locating each lever in manufacturing but the adjusting nut is locked in place and should never be disturbed, unless the clutch is dismantled for replacement of parts.

When the clutch pedal is depressed the release bearing is moved toward the flywheel and contacts the inner ends of the release levers, (1) fig. 9 and fig. 10. Each release lever is pivoted on a floating pin which remains stationary in the lever and rolls across a short flat portion of the enlarged hole in the eyebolt (2). The outer end of each release lever engages the pressure plate lug by means of a strut (3), which provides knife-edge contact between the outer end of the lever and the lug. The outer ends of the eyebolts extend through holes in the stamped cover (4), and are fitted with adjusting nuts (5) to correctly position the levers.

Clutch Pedal Adjustment

One simple adjustment is necessary to maintain clutch efficiency and assure long life. This adjustment sets the amount of free clutch pedal travel before the throwout bearing contacts the clutch levers. The adjustment is made by turning the adjusting block on the clutch fork push rod (to shorten the rod) which in turn will move the throwout lever and release bearing back away from the pressure clutch plate fingers. This adjustment should give enough travel between the throwout bearing and clutch fingers so that a movement of 3/4" to 1" may be felt at the clutch pedal when moved by hand.

Major Service Operations

Removal
Disassembly
Assembly
Adjusting Levers
Installation

Removal

Before removing clutch from flywheel, mark with a punch the flywheel, clutch cover and one pressure plate lug, so that these parts may be assembled in their same relative positions, as they were balanced as an assembly.

Disengage the clutch fork from the ball stud and remove the ball stud by screwing it rearward out of the clutch housing. Loosen the holding screws a turn or two at a time to avoid bending rim of cover. When removing driven plate be sure to mark flywheel side.

NOTE: It is advantageous to place nuts or metal spacers between the 3 clutch levers and the cover to hold the levers down as the holding screws are removed.

Disassembly

1. Place the cover assembly on the bed of an arbor or drill press with a block under the pressure plate so arranged that the cover is left free to move down.
2. Place a block or bar across the top of the cover and compress the cover with the 3 spindle. Hold compressed while the adjusting nuts are removed as shown in fig. 12, then slowly release pressure to prevent springs flying out.
3. Lift off cover and all parts will be available for inspection. Note carefully the location of all parts including arrangement of the springs, (see fig. 13).
4. To remove levers grasp lever and eyebolt between thumb and fingers as shown in fig. 14, so that inner end of lever and upper end of eyebolt are close together, keeping eyebolt pin seated in its socket in lever.
5. Lift strut over ridge on end of lever, (fig. 15).
6. Lift lever and eyebolt off pressure plate.

NOTE: It is important to replace all parts which show wear.

Assembly

1. Lay the pressure plate on the block in the press and coat the lugs with a thin film of approved lubricant such as lubriplate as shown in fig. 16. Also, apply a light film of high melting point graphite grease in the eyebolt holes in the pressure plate.
2. Assemble lever, eyebolt and pin, holding eyebolt and lever as close together as possible and with the other hand grasp strut as shown in fig. 17.
3. Insert strut in the slots in the pressure plate lug, drop slightly and tilt the lower edge until it touches vertical milled surface of lug.
4. Insert lower end of eyebolt in hole in pressure plate. The short end of the lever will then be under the hook of the pressure plate and near the strut, (fig. 15).
5. Slide the strut upward in the slots of the lug, lifting it over the ridge on the short end of the lever and drop it into the groove in the lever, (fig. 14).
6. Assemble the pressure springs, on the small bosses of the pressure plate in accordance with the table shown below, in order to re

NOTE: If there are spaces for more springs than specified for the particular assembly, or if two different colors of springs are used, the table and figure 18 show the proper sequence. It is very important that each group be arranged in like sequence.

TYPE        Spring Bosses on          Springs used per Clutch 
             Pressure Plate              
                    BETWEEN                 BETWEEN          Arranged 
CLUTCH    TOTAL      LUGS        TOTAL       LUGS         as Shown in FIG. 
11A7       12          4            9          3                18 <

1. Assemble anti-rattle springs in cover as shown in fig. 20. The spring to the left is in operating position.
2. Install centrifugal rollers in proper seats, as shown in fig. 18.
3. Lower the cover on top of the assembled parts, (fig. 20) being sure that the anti-rattle springs are in correct position and also that the punch marks made before dismantling are matched to insure retaining the original balance.
4. Place a bar across the cover, as shown in fig. 12 and slowly compress, guiding the holes in the cover over the pressure plate lugs and all springs into their spring seats in the cover.
5. Assemble adjusting nuts on the eyebolts and screw them down until their tops are flush with the tops of the eyebolts. Slowly release pressure of spindle and remove cover assembly from press.

NOTE: To adjust levers it is necessary to use Tool 1048 on the flywheel in the car or on a spare flywheel at the bench.

1. Place gauge plate on the flywheel in the position normally occupied by the driven plate as shown in fig. 21.
2. Bolt cover on flywheel with the gauge plate centered and with the three flat machined lands placed directly under the levers.
3. Depress each lever several times with a hammer handle as shown in fig. 22 to settle all of the parts into working position.
4. Make a sheet metal lever height gauge like that shown in fig. 23 or use Tool 6456. The step (or notch), should be 1/8", by approximately 5/16" long.
5. Lay the height gauge across the hub of the gauge plate and the bearing surface of one lever and turn the adjusting nut until the lever is flush with the height gauge. Then adjust the other levers in the same manner.
6. Stake the nuts with a dull punch as shown in fig. 24 driving metal from the nut into the grooves in the eyebolt to provide a secure lock.
7. Loosen the holding screws a turn or two at a time until the spring pressure is relieved which will allow clutch and gauge plate to be removed.

1. Assemble driven plate and clutch cover assembly to flywheel in accordance with marking on driven plate for flywheel side. Depressing clutch levers on a press (using a release collar and bearing assembly) and installing spacers to hold levers down will facilitate installation and prevent cover distortion during tightening. Be sure to remove spacers after bolting clutch to flywheel. NOTE: The driven plate and/or the special, short, flat faced release collar and bearing assembly is used with this clutch and cannot be interchanged with that which is used with the diaphragm spring clutch.
2. Line up the driven plate assembly and the pilot bearing with a dummy shaft before tightening cover holding screws. Tighten holding screws before removing dummy shaft.
3. After transmission has been assembled adjust pedal as directed under "Clutch Pedal Adjustment."

COIL SPRING CLUTCH

Symptom and Probable Cause
Probable Remedy


Slipping

a. Improper adjustment.
a. Adjust pedal travel.

b. Oil soaked.
b. Install new disc.

c. Worn splines on clutch gear.
c. Replace transmission clutch gear.

d. Lining tom loose from disc.
d. Install new disc.


Grabbing

a. Oil on lining.
a. Install new disc.

b. Worn splines on clutch gear.
b. Replace transmission clutch gear.

c. Loose engine mountings.
c. Tighten or replace mountings.


Rattling

a. Weak retracting springs.
a. Replace springs.

b. Throwout fork loose on ball stud.
b. Check ball stud and retaining spring and replace if necessary.

Coil Spring Clutch Specifications

Type....................Single Plate Dry Disc
Diameter - V-8 - 10"
Clutch Pressure Spring
V-8 (with Power Package) 9 Coil Springs

Clutch Release Bearing
    Type....................Sealed Ball
    Make....................New Departure

Clutch Pilot Bearing
    Type....................Oil Impregnated Bushing

Transmission Pilot Hole
    Runout not to exceed....Bushing
.008"                  Oil Impregnated

Clutch Pedal
Free Pedal Travel - 3/4'P to 1"