Pay attention to the position of your left foot when driving a car. Most novice drivers have their foot tied to the clutch pedal. The worst thing for the clutch is if the car with the novice driver starts to skid. In these conditions, if no one more experienced intervenes in time, the clutch will not last very long.
Clutch faults can be divided into two categories: those that can be fixed without removal and disassembly; can only be eliminated by replacing the failed parts with new ones.
The first category includes faults related to the violation of the free travel of the clutch pedal and air entering the hydraulic system of the clutch drive. Free travel of the pedal is a serious factor affecting the correct operation and lifespan of the clutch. The operation of the clutch without slipping depends on the free travel. Incomplete disengagement of the clutch is often accompanied by noise when engaging gears and is caused by an increase in the free travel of the clutch pedal.
If air has entered the hydraulic system, first of all it is necessary to find out which part or connection is to blame for the air getting into the system. It is necessary to carefully inspect the entire route from the fluid reservoir to the clutch slave cylinder. Air can be sucked in through cracks in the tubes when the sealing rings of the master or slave cylinders are damaged. Where there are fluid leaks, air can also be sucked in. Naturally, tubes with cracks are replaced with new ones, and the system is bled. If fluid leaks are detected near the master or slave cylinders, they are removed, disassembled and the sealing rings are replaced - the most likely sources of leaks.
If you are going to replace one of the units or parts of the hydraulic clutch drive, you must first drain the brake fluid (remember that the hydraulic clutch drive system contains Neva brake fluid). This is very easy to do. One end of the hose should be put on the nipple 8 (see fig. 27) of the working cylinder, and lower the other end into a clean vessel; unscrew the nipple by 1/2-3/4 of a turn, press the clutch pedal until all the fluid flows out of the hydraulic drive. Let's assume that during the check a leak of fluid from the master cylinder is detected. This is already a malfunction related to the second category. The cylinder must be removed, disassembled and the failed parts replaced. To remove the master cylinder, you only need to unscrew the two nuts that secure it to the pedal bracket and remove the flexible hose connecting the reservoir to the cylinder.
The master cylinder should be disassembled on a clean table, with a tray of brake fluid, a brush for cleaning the parts, and lint-free napkins at hand. It is especially important to ensure that the parts of the master (working) cylinder do not come into contact with mineral oils, gasoline, kerosene, or diesel fuel. Remember that rubber parts operating in the Neva brake fluid environment do not tolerate these materials.
When starting disassembly, remove the rubber protective cap 12 (see fig. 26) and a retaining ring, then piston 5, sealing rings 4 and 13, floating piston 3 and spring 15. Having disassembled the master cylinder, assess the condition of the cylinder mirror. There should be no scratches or marks on it. Having replaced the sealing rings with new ones and having washed all the parts in brake fluid, the master cylinder can be assembled and installed in place. Before assembly, lubricate the parts only with brake fluid.
If the main suspicions fall on the rubber parts of the working cylinder, the cylinder must be removed, for which purpose the spring 6 (see fig. 27), unscrew the tube, remove the pusher and unscrew the two cylinder mounting screws. Cylinder disassembly begins with protective cap 11. Then remove pusher 3 and piston 12. Compressed air will help push out the piston, for which connect the pump hose to nipple 8, and close the hole in the housing plug with your finger. To disassemble the piston, remove the retaining ring, washer, spring. After replacing the seal or ring 10 and thoroughly washing housing 9, plug 7 and all disassembled parts in brake fluid, the working cylinder is assembled and installed in place.
The presence of air in the system can be easily determined by the behavior of the clutch pedal. It will move with little resistance (fail). The air is removed by bleeding the system. This is a simple operation. The only inconvenience is that it must be done by two people and on an inspection ditch or overpass. The operation is very similar to bleeding the brakes and is performed in the following sequence:
- remove the protective cap from the nipple 8 (see fig. 27) to bleed the clutch drive and remove dirt from the nipple;
- add fluid to the hydraulic drive reservoir to the required level (to the lower edge of the filler neck);
- put a hose on the head of the fitting and lower its lower end into a container with liquid;
- unscrew the nipple by 1/2-3/4 of a turn and sharply press the clutch pedal, then release it smoothly. These exercises should be performed until air stops coming out of the system.
During the pumping process, make sure that the end of the tube is not exposed (otherwise air will be sucked into the system), connecting the reservoir to the master cylinder, and the end of the bleed hose was constantly immersed in liquid.
The second category of faults also includes: warping of the driven disk; loose rivets, uneven surfaces or broken friction linings of the driven disk; breakage of the plates connecting the thrust flange to the clutch housing; jamming of the driven disk hub on the splines of the drive shaft; loosening of the pressure spring rivets.
To find out which of these defects is to blame for the incomplete disengagement of the clutch, it is necessary to remove the clutch and inspect each of its parts. The clutch is removed on an inspection ditch or overpass. Getting to the clutch is not so easy. There is a lot of work, although not very difficult, since the clutch is clamped on one side by the engine, and on the other - by the gearbox, propeller shaft, etc. When removing the clutch, the car must be securely standing on an inspection ditch or overpass with stops under the front wheels and stands under the rear jack sockets (the rear axle needs to be lifted). Since you will need to manually turn the driveshafts while standing below, be sure to set the gearshift lever to neutral and disconnect the wires from the battery.
To get to the clutch, you need to remove the gearbox. You will have to start this work in the body interior in the following order:
- remove the front floor mat and outer gear shift boot;
- unscrew the four screws and remove the plastic cover of the gearshift lever hatch and the seal;
- pressing the lever rod down, use a thin screwdriver to remove the thrust ring from the groove on the lever rod;
- since the exhaust pipe and the mufflers themselves will interfere with removing the gearbox, you need to loosen the clamp that connects the exhaust pipe to the muffler pipe and remove them together with the muffler hangers. Also disconnect the clamp that secures the exhaust pipe to the gearbox;
- from the engine compartment, unscrew the nuts securing the inlet pipe to the exhaust manifold, after which the inlet pipe can be removed;
- unscrew the bolts securing the clutch housing cover to its lower part;
- unscrew the bolt securing the ground wire to the clutch housing;
- remove the cotter pin from the end of the pushrod;
- remove the clutch slave cylinder together with the tube connecting it to the master cylinder. Then there will be no need to bleed the hydraulic drive system;
- unscrew the nuts and remove the cardan shaft safety bracket;
- disconnect the speedometer flexible shaft from its drive; disconnect the cardan shaft. To facilitate the removal of the cardan shaft, service stations use a simple device - a hoop with a tension screw. The hoop is put on the elastic coupling and the coupling is compressed using a screw. In this position, unscrew the nuts and, turning the cardan shaft, remove the bolts securing the gearbox flange to the elastic coupling. It is advisable to make such a device yourself, as it will come in handy and help when assembling the transmission;
- move the disconnected cardan shaft together with the coupling to the side;
- end (best with a hinge) use a wrench to loosen the bolts securing the starter to the clutch housing;
- unscrew the bolts securing the rear engine mount to the crossmember, and then the nuts securing the crossmember to the body;
- using the available means, construct a reliable support for the gearbox from below and only then unscrew the four bolts securing the clutch housing to the cylinder block. It should be added that a special socket wrench with a hinge is required for this operation.
The gearbox, freed from its fasteners, must be carefully moved backwards until the end of the gearbox drive shaft goes beyond the clutch. The end of the gearbox drive shaft must not rest on the thrust flange of the clutch pressure spring under any circumstances.
So, 95% of the work is done. All that remains is to disconnect the clutch from the engine flywheel. Just in case, mark the relative positions of the clutch and flywheel. This will come in handy during assembly if you have to reinstall the old clutch. After unscrewing the mounting bolts, remove the clutch housing together with the pressure plate. Do this carefully, remembering that between the clutch and the flywheel there is a driven disk that can fall on your feet.
To inspect the clutch (Fig. 52), no complicated equipment is required. You need a table whose surface would imitate the plane of the flywheel, and ring 4, made of any hard material 8.2 mm thick.
The clutch housing should be secured to the table and the pressure spring flange should be pressed 4-5 times (approximate pressing force 1.37-1.42 kN). With 8 mm of clutch engagement travel, the pressure plate should move 1.6-1.7 mm.
Clutch housing; together with the pressure disk it is necessary to change on condition that the size 40-43 mm, i.e. the distance from the table surface to the working surface of the friction ring of the thrust flange, does not exceed 48 mm or the size 1.6-1.7 mm is not less than 1.4 mm.
Inspection of the clutch components and assemblies should tell you what to do. If you find warping, the driven disk must be replaced. If the plates connecting the thrust flange to the casing are broken, or the spring rivets (pressure) are loose, you will have to replace the clutch casing together with the pressure disk. It happens that the reason for incomplete clutch disengagement is the jamming of the driven disk hub on the splines of the gearbox input shaft, i.e. there are burrs on the splines of the shaft or hub of the driven disk that prevent the disk from moving freely.
This defect is eliminated in the following way: the detected burrs are cleaned with sandpaper, and then the splines are wiped and lubricated with a thin layer of consistent grease LSC-15 or Litol-24.
Having clarified all the questions of interest, the clutch can be installed in place. In addition to the tool available in the driver's kit, you will also need the old, worn-out, drive shaft of the gearbox to ensure the alignment of the driven disk with the crankshaft bearing. When installing the gearbox in place, in most cases the drive shaft does not fit due to the misalignment of the splines. To overcome this obstacle, you need to engage the gear and, rotating the flange (from the opposite end of the box), help the drive shaft find its place.
In order not to confuse how to install the driven disk, we remind you: the driven disk is installed with the protruding part of the hub with the annular groove towards the gearbox, the casing is applied together with the pressure plate and only then the casing and driven disk are centered relative to the bearing (Fig. 53), i.e. a mandrel or an old roller is inserted. The centered casing is fastened with bolts to the flywheel, and then everything that was removed is installed.