On a car with a manual transmission, a single-disk, dry, central diaphragm spring clutch is installed
The drive disc (basket) is connected to the engine flywheel with six bolts.
There are three pins pressed into the flywheel that center the clutch cover.
A diaphragm spring is installed in the casing of the drive disk, which is stamped from sheet spring steel.
In the free state, the spring has the form of a truncated cone with radial slots extending from the inner edge of the spring.
Spring slots form eighteen petals, which are elastic release levers.
Due to the elasticity of the levers, the diaphragm spring creates a more even pressure on the clutch pressure plate, which contributes to smooth engagement and disengagement of the clutch.
At three points, the clutch cover is connected by elastic steel plates to the pressure (leading) disk.
The casing with the diaphragm spring and the pressure plate form a non-separable unit (it is also called the "clutch basket"), which is balanced on the stand.
In case of failure, the clutch basket is replaced entirely.
Replacement of the "basket" is necessary in case of severe annular wear of the petals of the diaphragm spring and if the ends of the petals are not located at the same level.
We also replace the “basket” in case of a decrease in pedal force when the clutch is released (and, accordingly, an increase in the working stroke), which indicates a large wear of the pressure plate surface or “settlement” of the diaphragm spring.
The driven disk with a spring damper of torsional vibrations is located on the splines of the input shaft of the gearbox between the engine flywheel and the pressure plate.
The vibration damper dampens vibrations resulting from dynamic loads in the transmission and uneven engine operation.
Two disc friction linings are riveted on both sides to a spring plate, which in turn is riveted to one of the two damper plates.
The spring plate has a wavy shape.
When the clutch is engaged, the friction linings compress the spring plate, which contributes to the smooth engagement of the clutch.
A disk hub is installed between the damper plates.
Damper springs are installed in the grooves of the hub and damper plates.
The damper plates are connected by support posts.
There are notches in the disc hub opposite the support legs that allow the hub to rotate within certain limits relative to the damper plates, while compressing the damper springs.
This allows you to reduce dynamic loads in the transmission when starting the car and shifting gears.
An idle damper is located on the hub of the driven disk in a plastic housing, which serves to eliminate knocking in the gearbox when the engine is idling.
The driven disk is replaced if its axial runout in the area of the friction linings is more than 0.5 mm, oiling, cracking, scuffing or uniform wear of the linings, loosening of rivet joints, and also if the distance between the working surface of the lining and the head of the rivet is less than 0.2 mm.
The working cylinder of the hydraulic drive is made as a single unit with the clutch release bearing (release bearing) and is located inside the clutch housing.
The slave cylinder is attached to the clutch housing.
The movable part of the working cylinder is connected to a bearing that can move along the input shaft of the gearbox.
A spring (covered with a rubber corrugated boot) located between the cylinder and the bearing race constantly presses the bearing against the diaphragm spring of the clutch basket.
Therefore, there are no gaps in the clutch mechanism and no adjustment is provided.
Closed release bearing.
There is grease inside the bearing.
The clutch hydraulic actuator consists of a master and slave cylinder, which are connected by a pipeline.
The working fluid is poured into a reservoir mounted on the main brake cylinder.
The clutch master cylinder is connected to the reservoir by a rubber hose.
The master cylinder is mounted on the bulkhead, and its rod is connected to the clutch pedal.
To bleed the clutch hydraulic drive, there is a fitting on the plastic tip of the hydraulic drive tube, closed with a rubber cap.
Clutch disengagement is as follows.
When the pedal is pressed, the clutch release hydraulic system is pressurized.
Fluid pressure is transferred to the piston of the working cylinder, which moves the clutch release bearing along the axis of the gearbox input shaft.
The bearing presses on the petals of the diaphragm spring of the pressure plate.
The spring, deforming, retracts the pressure plate, as a result, the pressure plate ceases to press the driven disc against the flywheel.
The crankshaft of the engine and the input shaft of the gearbox in this case can rotate independently of each other.
When the clutch pedal is released, the bearing returns to its original position, while the diaphragm spring again begins to press on the pressure plate, which in turn presses the driven disc against the flywheel - as a result, the transmission of torque resumes.
Bleeding the hydraulic clutch
We pump the clutch hydraulic drive to remove air from it after depressurization when replacing the main or working clutch cylinders, tubes and hoses, as well as when removing the main brake cylinder or reservoir of hydraulic brakes and clutch.
For bleeding the hydraulic clutch, there is a fitting on the plastic tip of the tube, closed with a rubber cap.
The adapter, on which the tip of the tube is put on, is not fixed in the clutch housing, therefore, for the convenience of pumping, we recommend making a locking washer from a metal washer (1.0-1.2 mm thick, 23 mm outer diameter and washer for adapter.
Before pumping, we check the levels The amount of fluid in the reservoir. If necessary, add liquid.
We install the manufactured lock washer in the groove of the adapter (for clarity, it is shown with the tube tip removed).
Remove the protective cap from the bleed valve.
We put a transparent hose on the fitting, the other end of which is lowered into a container partially filled with working fluid so that the free end of the hose is immersed in the liquid.
The assistant presses the clutch pedal several times and keeps it pressed.
Press on the spring retainer of the tube tip
Move the tip of the adapter tube by 4 - 6 mm
At the same time, part of the brake fluid and air are displaced into the container.
Air bubbles are clearly visible in the liquid container.
After the liquid stops flowing into the container, we put the tip of the tube on the adapter until it stops.
The assistant can then release the clutch pedal.
Repeat this operation until the exit of air bubbles from the hose stops.
Remove the hose and put a protective cap on the fitting.
When pumping, we control the level of liquid in the tank and, if necessary, add liquid.
Possible clutch failures and solutions
Cause of failure (Remedy)
Incomplete clutch disengagement (clutch leads):
- Reduced full travel of the clutch pedal
Repair the clutch release
- Warping of the driven disk (end runout)
Replace driven disc
- Irregularities on the surfaces of the friction linings of the driven disk
Replace driven disc
- Loose rivets or breakage of the friction linings of the driven disk
Replace driven disc
- Jamming of the hub of the driven disk on the splines of the input shaft of the gearbox
Clean the splines, coat with LSC-15 grease
If jamming is caused by crushed or worn splines, replace the input shaft or driven disc
- Air ingress into the hydraulic drive system
Bleed the system
- Fluid leakage from the master or slave cylinder of the clutch release
Replace master or slave cylinder
- Loosening the rivets of the pressure spring
Replace clutch cover with pressure plate assembly
- Skewed or warped pressure plate
Replace clutch cover with pressure plate assembly
Incomplete clutch engagement (clutch slips):
- Increased wear or burning of the friction linings of the driven disk
Replace driven disc assembly
- Damage or jamming of the clutch release actuator
Troubleshoot
Clutch jerks:
- Jamming of the hub of the driven disk on the splines of the input shaft
Clean splines, grease with graphite grease
- Breakage or decrease in the elasticity of the driven disk damper springs
Replace driven disc
- Jamming in the clutch release mechanism
Replace deformed parts
- Increased wear of the friction linings of the driven disk
Replace driven disc
- Loosening the rivets of the friction linings of the driven disk
Replace driven disc
- Basket damage
Replace clutch basket
Increased noise when disengaging the clutch:
- Wear, damage or leakage of grease from the clutch release bearing
Replace bearing
Increased clutch noise:
- Breakage of the plates connecting the pressure plate to the casing
Replace clutch basket
Clutch slippage can be easily determined by the tachometer.
If, while driving, when you sharply press the gas pedal, the speed rises sharply, and then does not they fall a lot and the car starts to accelerate, the clutch needs repair.