Section 6r

Engine - Clutch

Index
Figure Index
General Description
Operation
Care, Maintenance and Adjustments
Clutch Pedal Height
Clutch Pedal Pull Back Spring
Clutch Pedal Free Travel
Clutch Retracting Springs
Clutch And Brake Pedals
Major Service Operations
Removal
Disassembly
Inspection
Repairs
Pilot Bearing
Assembly
Troubles and Remedies
Clutch Specifications

Figure Index

The clutch used on all standard transmission models 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 entire clutch assembly is mounted on a splined transmission clutch gear and bolted to the flywheel through the clutch cover. 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 caps, 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.

The clutch pedal is of the suspended type, providing maximum toe space in the drivers 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 either to the clutch pedal or to 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

There are three adjusting points on the clutch linkage. A complete adjustment covers all three.

CLUTCH PEDAL HEIGHT

Should the level or height of the clutch pedal not match that of the brake pedal, the clutch lever bumper bracket "1," fig. 5, located on the right side of the dash panel to instrument panel brace, may be adjusted. The bracket is held in place by a bolt and nut. The slotted hole in the brace allows for sufficient adjustment to bring the clutch pedal to the same level as the brake pedal.

A change in clutch Pedal height may necessitate a pull back spring adjustment and a pedal free travel adjustment.

NOTE: If pedal is low and clutch lever is not contacting or compressing rubber bumper on return stop, it will be necessary to increase the pull back spring tension before the height is adjusted.

Clutch Pedal Pull Back Spring

A heavy spring is utilized for the dual purpose of pulling the pedal back against the stop and assisting clutch operation through an over-center action. The over-center action is not adjustable separately from the pull-back action. Should the pedal fail to return to the stop upon a slow-pedal release, or excessive pedal pressure is evident a noted in the free travel check, an adjustment is provided at the upper end of the clutch pedal. With the correct adjustment, 6 to 9 pounds should be required to push the pedal off the stop. A change in pull back spring tension may require a small change in pedal height.

1. Remove rubber bumper from clutch pedal return stop bracket on right side of dash panel to instrument panel brace.
2. Allow pedal to rise until clutch rod lever is against stop bracket.
3. Insert a screw-driver or pry bar between the underside of the dash panel to instrument panel brace and the topside of the clutch pedal return spring lever, "2", fig. 14.
4. Loosen the two clutch pedal to clutch pedal return spring lever bolts, reposition lever to increase or decrease spring tension as required, and retighten bolts.
5. Depress clutch pedal and install rubber bumper in clutch rod lever stop bracket.
6. Check adjustment.

The most important adjustment as far as clutch operation is concerned is free travel, or pedal travel before release or throwout bearing contacts clutch diaphragm spring fingers. The pedal should travel 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. If free travel is very difficult to feel, the pull back spring tension should be decreased to allow the travel to be checked. This indicates excessive tension.

1. Loosen check nut "3" (fig. 5).
2. Turn adjusting nut "4" to remove all lash at fork, then back off two turns.
3. Tighten check nut "3."

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.

Integral clutch and brake pedal assemblies are provided on passenger models equipped with syncro-mesh transmissions. The same brake pedal assembly is used on models equipped with Powerglide. In either case the pedal assembly is suspended from a brace fastened from the instrument panel to dash panel fig. 14. Both pedal assemblies are removable for service. The brake pedal assembly is mounted to the panel brace utilizing nylon bushings on the brake shaft which is installed through the opening provided on the panel brace. Since the brake pedal shaft is hollow, the clutch pedal shaft is conveniently installed through the brake pedal shaft, again using nylon bushings and adjustable linkage. A brake pedal coil spring used in the assembly returns the pedal to its original position after brake application. A clutch pull back spring permits smooth light operation to engage or disengage the clutch. When the pedals are not in use, spring tension from the springs holds the pedal arms back against rubber stops. The rubber stops are removable for replacement.

Clutch Pedal Assembly

Removal

1. Disconnect the clutch push rod from the push rod lever.
2. Release the pull back spring tension by pushing the clutch pedal down to the end of its forward travel against the floor board.
3. Remove the adjustable bolt after securely tightening the non-adjustable bolt.
4. Loosen the upper non-adjusting bolt slowly relieving pull back spring tension.
5. Pull pedal back against the stop bracket.
6. Remove the pull back spring.
7. Remove the clutch push-rod lever retaining bolt.
8. Remove the clutch push rod lever and spacer.
9. Remove the clutch pedal shaft assembly and bushing.

Inspection

1. Clean all metal parts with a good cleaning solvent.
2. Wipe the nylon bushings clean with a clean cloth.
3. Inspect the clutch pedal shaft for damage to the serration on the end of the shaft.
4. Inspect the clutch pedal lever for wear, bend, or damaged teeth.
5. Inspect the nylon bushings for wear.
6. Replace all worn or damaged parts.

Installation

1. Install the clutch pedal pull back spring lever to the clutch pedal with the non-adjustable retaining bolt only.
2. Tighten the retaining bolt until the lock washer is partly compressed and there is a heavy drag between the bracket and pedal arm with hand pressure.
3. Lubricate the nylon bushings with lubriplate or a similar lubricant and install one on the clutch pedal shaft with the shoulder of the bushing flush against the pedal arm.
4. Lubricate the clutch pedal shaft with lubriplate or a similar lubricant and install the assembly through the brake pedal sleeve.
5. Install the second nylon bushing on the clutch pedal shaft and push it into the brake pedal sleeve, lubriplate pull back spring ends.
6. Connect the clutch pull back spring on the instrument panel brace with the short hook of the spring to the panel brace.
7. Connect the other end of the pull back spring to the clutch pedal arm.
8. Pull the clutch pedal back to the end of its return travel.
9. Insert a large screwdriver or other suitable tool under the panel brace and over the clutch pull back spring lever.
10. Pull down on the spring lever with the tool until the slotted hole in the clutch pedal pull back spring lever is aligned with the tapped hole in the clutch pedal arm.
11. Install the adjusting bolt, flat washer and lock washer at the approximate center of the slot.
12. Install the steel spacer over the serrated end of the clutch shaft next to the nylon bushings. CAUTION: Be sure the nylon bushing is correctly seated.
13. Install the push rod lever on the clutch shaft with the arm next to the spacer.
14. Install the push rod lever retaining bolt, lock washer and nut.
15. Adjust the clutch pedal pull back spring tension as outlined under "Clutch Pull Back Spring Adjustment" below.
16. Connect the clutch pedal push rod lever and push rod with the spring, flat washer and cotter pin.

Clutch Pedal Pull Back Spring Adjustment

The clutch pedal requires 6 to 9 pounds to be moved off the stop and returns to the rubber stop by proper adjustment of the clutch pedal pull back spring which is located above the clutch pedal arm.

It has approximately 175 pounds pull under load.

It is important that the pull back spring be correctly adjusted and the adjustment be maintained in order to preserve the feel of ease in operation when the driver engages or disengages the clutch pedal. Due to the high tension of the spring when it is under load, care must be used when the adjustment is made.

1. Remove the rubber stop.
2. Loosen the adjustable bolt.
3. With a suitable tool or large screwdriver resting under the instrument panel brace and over the return spring lever, push the return spring lever down against the force of the spring and until the bracket is located in the approximate center of the slot.
4. Tighten the adjustable bolt securely in this position.
5. Remove the pry bar or heavy screwdriver.
6. Install the rubber stop. NOTE: With correct adjustment the clutch pedal requires 6 to 9 pounds to move it off its stop, stop will be compressed, free travel may be felt.

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 1" free travel before the clutch starts to disengage.
2. Check the clutch pedal bushing for sticking on the shaft or loose mountings.
3. Lubricate the pedal linkage.
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.

REMOVAL

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 Clutch Pilot Tool, J-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.

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 Pilot Bearing Puller J-1448 and remove bearing from crankshaft (fig. 7). In replacing this bearing, use clutch pilot bearing driver J-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 attaching bolts and tighten each one a turn at a time to prevent distorting the cover as the spring pressure is taken up.
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.

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

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

Noisy

a. Worn throwout bearing
a. Replace bearing

Pedal Height, Tension

a. Pedal low, clutch lever not contacting rubber stop bumper.
a. Increase pull-back spring tension.

b. Pedal low, clutch lever compressing rubber stop bumper.
b. Adjust pedal stop.

c. Pedal high.
c. Adjust pedal stop.

d. Lack of free pedal travel feel.
d. Decrease pull-back spring tension.

Clutch Specifications

Type - Single Plate Dry Disc
Disc Diameter-V-8 - 10"
Disc Diameter-In Line 6 - 9 1/2"

Clutch Pressure Spring
Type - Diaphragm
Diameter - 9"

Clutch Release Bearing
Type - Sealed Ball
Make - New Departure

Clutch Pilot Bearing
Type - Oil Impregnated Bushing

Clutch Pedal
Pedal Pressure - 6 to 9 Pounds To Start Pedal Movement