The clutch of cars is dry, single-disk, with a damper device, installed in a cast aluminum crankcase (Fig. 1)

The clutch of the GAZ-66 car differs from the clutch of the GAZ-53A car only by different thrust pins of the clutch release forks (due to different clutch release drives), covers of the ignition installation hatches and the presence of an ignition installation pin pressed into the clutch housing of the GA3-66 car ( there is no pin in the GAZ-53A clutch housing).

Pressure and driven disks, as well as clutch release clutches for GAZ-53A and GAZ-66 cars have no differences.

The drive for disengaging the clutch of the GAZ-53A car is mechanical (see Fig. 1), the GAZ-66 car (race 2) is hydraulic.

Clutch maintenance

When lubricating the thrust bearing of the clutch release clutch, it is necessary to squeeze out the lubricant in the amount of one full filling of the cap oiler.

More frequent and heavy lubrication may cause excess lubricant to get on the clutch discs, which may cause failure.

Rather lubrication of the bearing leads to thickening of the lubricant in the holes that supply it from the annular cavity of the coupling to the bearing, and to the subsequent failure of the bearing due to the cessation of the supply of lubricant.

Special attention should be paid to caring for the GAZ-66 clutch release drive in connection with the use of GTZh-22 fluid as a working fluid, since it has strong oxidizing properties.

For the normal operation of the clutch of the GAZ-53A car, it is necessary to ensure a gap between the heads of the clutch release levers and the thrust bearing of 4 mm.

To obtain this clearance, it is necessary to periodically check and adjust the free play of the clutch pedal, which should be 35-45 mm.

The free travel of the clutch pedal is regulated by changing the length of the rod connecting the clutch release fork to the lever on the pedal shaft.

An increase in free play is achieved by unscrewing the nut on the rod, a decrease - by wrapping it.

For the normal operation of the clutch of the GAZ-66 car, it is necessary to ensure a gap between the heads of the release levers and the thrust bearing of 2 mm and a gap between the pusher and the master cylinder piston of 0.5-1.5 mm.

When adjusting the clutch release drive, first adjust the gap between the pusher and the master cylinder piston with an eccentric bolt 26 (see Fig. 2).

Normal clearance corresponds to a pedal free play of 3.5 - 10 mm.

After adjusting, tighten the nut of bolt 26.

If with the help of an eccentric bolt it is not possible to provide the required free play of the pedal, then it is preliminarily regulated by changing the length of the rod 7.

The gap between the thrust bearing of the clutch release and the heads of the levers is adjusted by changing the length of the pusher of the working cylinder, while it is necessary to obtain a free play of the end of the clutch release fork of 3.5 mm.

After adjustment, the total pedal travel should be 30-37 mm.

For normal operation of the clutch, it is also necessary to ensure that the piston stroke of the working cylinder is at least 23 mm.

With a smaller stroke, the clutch may not fully disengage. The piston stroke of the working cylinder is not regulated.

Reduced travel indicates air in the hydraulic drive system. In this case, it is necessary to pump the fluid in the hydraulic drive.

To do this, after removing the rubber protective cap from the head of the bypass valve of the working cylinder, put a bleed hose on the head.

Dip the end of the hose into a glass vessel, into which a little liquid is poured, and unscrew the valves by - ¾ turn.

Having screwed the tire pump hose to the threaded tip of the master cylinder plug, create a slight pressure in the system with the pump (Fig. 3).

This forces fluid from the master cylinder reservoir to fill the hydraulic drive system, forcing air out through the slave cylinder bypass valve.

The air from the hose will pass through the liquid in the glass vessel in the form of bubbles.

After the air stops flowing from the hydraulic drive system (bubbles stop coming out of the bleed hose), close the valve, remove the bleed hose.

Put a protective cap on the bypass valve head and, unscrewing the master cylinder plug, add liquid to a level of 15-20 mm below the upper edge of the filler hole; wrap the cork.

When pumping, the bottom of the master cylinder must not be exposed.

Therefore, if about a glass of liquid has leaked out of the system, stop pumping and continue it only after adding liquid to the main cylinder.

Clutch problems and how to fix them

- Causes of malfunction

Remedies

Unsmooth clutch engagement:

- Oiling the friction linings of the driven disk

Replace the driven disc or install new friction linings.

If the oiling is small, then you can sand the lining with fine sandpaper, after washing them with gasoline

- Non-simultaneous pressing of the thrust bearing on the heads of the clutch release levers

Adjust the relative position of the lever heads using nuts 7 (see Fig. 1) of the support forks

- High wear of friction linings (before rivets)

Replace disc or change pads

Incomplete clutch disengagement - “clutch will reduce” (difficult gear engagement and gear noise in the gearbox when shifting):

- Presence of air in the hydraulic drive system

Bleed fluid in the system

- Large clutch pedal free play

Adjust clutch pedal freeplay

- deformation of the driven disk

Replace or repair disc

- Non-simultaneous pressing of the bearing on the heads of the clutch release levers

Adjust the relative position of the levers

- Wear of the inner cuff of the master cylinder

Replace cuff

Incomplete engagement - “clutch slips”:

- Lack of clearance between the heads of the clutch release levers and the end face of the thrust bearing

Adjust clutch pedal freeplay

- Weakening of the clutch pressure springs

Replace springs

- Oiling discs

Replace discs or friction linings

- Excessive wear of the friction linings, friction surface of the flywheel or pressure plate

Replace the driven discs or disc linings, and repair the flywheel and pressure plate by grinding the friction surfaces

Noise, squeak when pressing the clutch pedal:

- Lack of lubrication in the clutch release bearing

Lubricate the bearing

- Clutch release bearing wear

Replace bearing

Clutch repair

The main parts of the clutch that require replacement or repair during operation are the driven and pressure plates, as well as the clutch release bearing.

Replacing the clutch release bearing

To remove the clutch release clutch bearing, remove the gearbox together with the clutch, disconnect the clutch return spring, remove the clutch and press the bearing off it.

Before pressing a new bearing onto the coupling, check that it is filled with grease.

When installing a gearbox with a clutch on a car, make sure that the lubricant supply hose to the bearing is not damaged, to do this, fill it inside the clutch housing before final installation of the gearbox on the clutch housing studs.

If the hose for supplying grease to the bearing was removed or replaced for any reason, then fill it with grease when installing.

To do this, squeeze the contents of a fully filled cap oiler into it twice; only the third time the oiler will supply grease to the clutch release bearing.

Removing the clutch discs

To remove the clutch discs from the vehicle, remove the gearbox.

Having removed the lower part of the clutch housing, unscrew the bolts securing the clutch housing to the flywheel through the lower crankcase hatch.

In this case, all the bolts should be unscrewed gradually so as not to bend the casing support legs or break the bolts that are unscrewed last.

Clutch discs separated from the flywheel are removed from the crankcase in a certain position.

First, the pressure plate is removed by turning it down with one of the paws of the casing and lifting the driven disc (Fig. 4), then the driven one.

Disassembly and assembly of the clutch pressure plate

The pressure plate is disassembled in the following order:

• - make marks on the casing and pressure plate in order to maintain the original position of these parts during assembly and, therefore, maintain balance coding;
• - put the disk on the press table, placing a wooden stand under the disk so that the paws of the casing can move down;
• - a wooden block is placed on top of the casing so that it does not cover any of the adjusting nuts of the support forks of the clutch release levers (Fig. 5);
• - pressing the bar with a press, compress the clutch springs in order to unload the clutch release levers from the forces, unscrew the nuts of the support forks of the levers, slowly release the press, remove the clutch cover, support fork springs and pressure springs;
• - carefully remove the fingers that fit in the protrusions of the pressure plate, separate the levers with support forks from the pressure plate and assemble the rollers of the needle bearings;
• - carefully remove the fingers of the support forks of the levers, separate the support forks and assemble the rollers of the needle bearings.

If warpage, scoring, annular grooves or cracks caused by overheating are found on the friction surface of the pressure plate, the disc is replaced or repaired by turning and grinding; the thickness of the repaired disc should be less than the thickness of the new disc by no more than 1.5 mm.

The difference in size from each of the axes of the three holes under the axis of the clutch release levers to the machined surface should be no more than 0.15 mm, and the surface itself should be flat (when checking on the plate, the 0.05 mm probe should not pass through).

Broken or loose pressure springs must be replaced (preferably all springs should be replaced).

The pressure spring force should be 62.5-68 kg when compressed from a free length of 61 mm to a length of 40 mm.

The springs of the support forks of the clutch release levers that have lost their elasticity must also be replaced, because otherwise, at high engine speeds, the heads of the release levers can move back, and this will cause continuous operation of the thrust bearing and premature wear.

When the support fork spring is compressed from a free length of 12.5 mm to a length of 9.5 mm, the spring force should be 14 ± 1.5 kg.

The pressure plate with the casing and levers is assembled in the following order:

• - assemble clutch release levers with support forks; for this, rubber balls with a diameter of 8.5 mm are placed in the corresponding holes of the levers, after which the gaps between the balls and the walls of the holes are filled with rollers of needle bearings (each bearing should have 19 rollers). Rubber balls are necessary so that the rollers do not crumble during assembly.
• - After installing the rollers, one or two drops of oil used to lubricate the gearbox are injected into the holes of the levers;
• - insert the clutch release levers with rollers into the slots of the support forks, then carefully insert the fingers and cotter them. Rubber balls are pushed out with fingers during assembly;
• - in the same way they assemble the pressure plate with the clutch release levers;
• - using, as in disassembly, a press, a wooden lining and a bar, they assemble the pressure plate with a casing, springs and heat-insulating washers. At the same time, the marks applied during disassembly on the disk and casing are aligned.

When assembling a casing with a repaired disk, metal washers are placed under the pressure springs in addition to heat-insulating washers to compensate for the reduction in the thickness of the disk and thus preserve the force of the pressure springs (instead of placing washers under the springs, you can make an annular groove of the flywheel under the paws of the pressure disk, the depth of the groove should be equal to the amount by which the thickness of the pressure plate has decreased after repair).

After assembly, adjust the position of the heads of the clutch release levers.

In the absence of a fixture, this operation can be carried out using a free flywheel.

To do this, the pressure plate, assembled with the casing, is placed on the friction surface of the flywheel.

Between the pressure plate and the flywheel, washers 10.2 mm thick are placed in three places and the bolts securing the casing to the flywheel are wrapped.

With the help of adjusting nuts of the pull levers, it is ensured that the size from the surface of the flywheel to the ends of the levers is 53 ± 0.75 mm (Fig. 6), and the deviation of the ends of the levers from one plane is no more than 0.3 mm;

- after that, the adjusting nuts are punched. Instead of washers when adjusting, you can use a new driven disk.

Clutch disc repair

In case of high wear (almost to the rivets) or damage to the friction linings of the driven disk, the linings are replaced.

Both pads must be replaced at the same time, as the difference in the thickness of the pads will disrupt the normal operation of the clutch.

To remove worn or damaged linings, drill and carefully tap out the rivets securing the linings to the leaf springs and disc.

Rivet new linings so that the rivet sinking depth is at least 1.5 mm.

The runout of a disc with new linings should be no more than 0.7 mm when measured at a radius of 125 mm from the center of the disc.

If the disc runout is greater than the allowable value, then when disengaged, the clutch will “lead” (incomplete disengagement of the clutch).

If necessary, the driven disk is corrected using the mandrel shown in fig. 7.

Installing clutch discs. Repaired clutch discs are installed on the car in the following order:

• - in the hole of the ball bearing of the drive shaft of the gearbox installed in the flywheel, put a refractory grease (constaline or grease 1-13);
• - wipe the friction surfaces of the flywheel and pressure plate with a piece of clean cloth slightly moistened with gasoline;
• - they are brought into the crankcase, first the driven disk, making sure that the short part of its hub is facing the flywheel, then the pressure disk is inserted, turning one of its support legs down and pressing it against the flywheel;

• - center the driven disk in relation to the axis of the engine crankshaft. For this, a mandrel is inserted into the splined hole of the disc hub through the rear hole of the clutch housing, shown in Fig. 8, so that the end of it enters the ball bearing in the flywheel.
• To center the driven disk, you can use the free drive shaft of the gearbox;
• - before fixing the clutch cover on the flywheel, the marks on the flywheel and the cover are combined, which are knocked out at the factory after the joint balancing of the crankshaft with the flywheel and the clutch;
• - gradually tighten all the bolts securing the casing to the flywheel;
• - install the gearbox and the lower part of the clutch housing.

Repair of the GAZ-66 clutch release drive

After disassembling the master and slave cylinders, inspect their parts, as well as the parts of the pedal bracket.

Nominal dimensions and limit dimensions to which wear of parts without repair is permissible are indicated in Table. 5.

Tab. 5 Nominal and maximum permissible dimensions without repair clutch release drive parts, mm
name	Nominal size	Size allowed
Hole diameter master cylinder for piston	22+0.023	22,085
Piston outer diameter master cylinder	22-0.040	21,810
Diameter of the bore of the working cylinder for the piston	24+0.023	24,085
Outer diameter of the piston of the working cylinder	24-0.020	23,840
Clutch pedal sleeve inner diameter	18+0.105	18,250
Internal diameter of pusher axle bushing	14+0.070	14,210

If scuffs or scratches are found on the mirror of the main or working cylinder, the cylinder should be replaced or it should be ground and honed to one of the repair sizes recommended in Table. 6 and 7.

Tab. 6 Repair dimensions of master cylinder parts clutch release drive
Name	Diameter, mm
	Cylinder	Pistons	Working Edges internal cuffs
Rated	22+0.023	22-0.040	23±0.2
1st repair	22.25+0.023	22.25-0.040	23.5±0.2
2nd repair	22.50+0.023	22.50-0.040	23.5±0.2

When assembling, it is allowed to install internal sealing collars of nominal size in the main cylinder of the first repair size.

Outer sealing collars of the nominal size can be installed for the first and second repair sizes.

In the working cylinder of the first repair size, it is allowed to install a sealing cuff of nominal size.

Repair dimensions of parts of the working cylinder of the drive clutch release
Year of issue	Size	Diameter, mm
		cylinder	piston	Working edges cuffs
Before June 1967	value	24+0.023	24-0.02	25+0.20
	1st repair	24.25+0.023	24.25-0.02	25.5+0.20
	2nd repair	24.5+0.023	24.5-0.02	25.5+0.20
Since June 1967	value	22+0.023	22-0.02	22.7+0.20
	1st repair	22.25+0.023	22.25-0.02	23.2+0.20
	2nd repair	22.5+0.023	22.5-0.04	23.2+0.20

The spherical tips of the pushers of the main and working cylinders, as well as the spherical recesses in the pistons of the cylinders and in the thrust pin of the clutch fork must be smooth, without scratches.

The tips of the pushers must mate with the notch mi pistons on a spot in the center of the spheres. If the contact occurs along the ring, then the pairing is incorrect and can cause sticking of the pusher, misalignment and wear of the piston.

When cleaning the sphere on the pushers with an emery cloth, it is necessary to ensure that the touch is not on the ring, but on the spot.

Inspect the ends of all plastic bushings and washers of the pedal bracket, carefully clean the burrs on their ends.

Check if the release and return springs are weakened.

If the springs are weak, replace them.