Removing the master brake cylinder of a GAZ-53A car must be done in the following sequence

Stop the engine and release the vacuum from the booster by depressing the brake pedal several times.

Disconnect the pipeline from the master cylinder coupling.

Displace the brake fluid from the master cylinder into the vessel by pressing the pedal several times.

Remove the rubber cap with compression ring from the end of the master cylinder.

Remove the brake pedal return spring. Remove the pin, pusher with rod and remove the protective cap with the clamping ring.

Remove the master cylinder from the pedal bracket. When unscrewing the bolts, it is recommended to use the wrench shown in fig. 1.

Removing the master brake cylinder of a GAZ-53A car

Removing the brake and clutch master cylinder of a GAZ-66 car must be performed in the following sequence.

Release the vacuum from the amplifier.

Disconnect the pipes from the master cylinder couplings.

Displace liquid from the main cylinder into the vessel.

Remove the master cylinder bracket with pedals assembly.

Remove the rubber caps with compression rings from the piston thrust cover.

Unscrew the nuts of the eccentric axles, remove the eccentric axles, remove the piston pushers with bushings (under the eccentric axles) and protective rubber caps from the cylinders.

Remove the cylinder from the pedal bracket.

Disassembly of the brake master cylinder must be done in the following sequence.

Clean the outer surface of the cylinder. Remove filler plug with gasket. Pour out the brake fluid remaining in the cylinder and reservoir.

Remove the couplings with copper gaskets.

Remove the retaining ring, thrust washer from the cylinder (or remove the thrust cover with gasket for GAZ-66), piston, cuff, spring with holder and valve.

Parts can be removed by blowing compressed air into the cylinder through the outlet port at the end of the cylinder.

Remove the master cylinder cover with gasket.

Repair of master cylinder parts

Wash all parts of the master cylinder in pure alcohol and wipe with a clean cloth. Check parts for wear and condition. The data of the maximum permissible dimensions of the parts of the main cylinder are indicated in Table. 1.

Nominal* and overhaul dimensions of master cylinder parts, mm


cylinder diameter

piston diameter

edge diameter

work cuffs


32.00+0.027 (32.08)

32.00-0.025 (31.85)

33 ± 0.2 (32.75)

1st repair



33.50 ± 0.2

2nd repair


32.50 —0.025

3rd repair



34.00 ±0.2

4th repair



Dimensions in parentheses are acceptable without repair

Master cylinder housing. Check for burrs and corrosion on the cylinder running surface. Clear

Crankcase overflow and outlet holes with a wooden stick, and compensation hole with soft blunt wire Ø 0.6 mm.

If there are signs of scuffing, corrosion and wear on the surface of the cylinder, it is honed to a diameter not exceeding 32.152 mm. In this case, install new cuffs.

If a leak appears after repair, then bore the cylinder, and then honing it to one of the repair sizes. At the same time, the corresponding sizes of pistons and cuffs are set.

Master cylinder pistonCheck for nicks, corrosion, wear, or clogged bypass holes.

If the spring valve riveted to the front end of the piston is not seated securely or has shifted so that the piston holes are open, reinstall the valve and secure it with additional punching.

Valve. Clean the valve before washing with a blunt tool and soak in alcohol to flush. Any damage or swelling must be replaced.

Carefully clean the filler plug of the cylinder from dirt and clean the ventilation hole.

Cuffs of the piston of the master cylinder must be elastic, and the working edges must be sharp and without flaws.

Assembly, installation on the vehicle and testing of the master cylinder

Before assembling, wash all parts of the master cylinder in pure alcohol and blow with compressed air. Lubricate the cuffs and the mirror of the cylinder with brake fluid.

Assemble the master cylinder in the reverse order of disassembly.

After the spring with valve and holder assembly, inner collar and piston are installed in the cylinder, check whether the piston returns well under the action of the spring.

After installing the washer and the retaining ring in the cylinder, check with a soft wire Ø 0.6 mm with a blunt end that the cuff compensation hole is not blocked.

After assembling the master brake cylinder, hole "A" with a diameter of 0.7 mm must not be blocked by a rubber cuff (Fig. 2). This is checked with a wire with a diameter of 0.6 mm.

The distance from the crankcase mounting flange to the end of the pusher must be 92.5 mm. The piston stroke must be no more than 37 mm (see fig. 2).

Brake master cylinder GAZ-66, GAZ-53

After installing the cylinder on the pedal bracket, install the pusher with cap assembly into the cylinder piston without putting the cap on the body.

Test the master cylinder, for this you need:

  • - install a hydraulic pressure gauge in the outlet;
  • - fill the cylinder reservoir with brake fluid to a normal level. During testing and after testing, add liquid if necessary;
  • - wrap the filler cap with a gasket;
  • - pump the cylinder by pressing the brake pedal 2-3 times, wipe the cylinder;
  • - check the cylinder for tightness under a pressure of about 90 kg/cm2. Pressure is created by pressing the pedal with a constant effort.

For 1.5 minutes there should be no leakage of liquid, pressure drop and pedal movement;

  • - check the cylinder valve for leaks, to do this, press the pedal and lower it.

Notice the pressure gauge; the valve must maintain an overpressure of 0.8 kg/cm2 in the system for one hour;

  • - disconnect the pressure gauge from the cylinder and attach the coupling with two new copper gaskets to its place with a bolt;
  • - connect the pipeline to the coupling;
  • - unscrew the filler plug and fill in the brake fluid to the normal level;
  • - wrap the cork with a gasket;
  • - put a rubber cap on the crankcase and secure it with a clamping ring;
  • - bleed the brake system.

When assembling the GAZ-66 master cylinder, take into account that an overpressure valve is not installed in the cavity of the clutch drive master cylinder, and the pistons rest against the cover.

Replacing hydraulic drive parts

Clean and rinse before replacing the part.

When replacing piping, hoses or tees, be sure too tighten their connection.

Brake pipeline is replaced in case of damage, dents of section narrowing.

When bending the pipeline in relation to its installation site, be careful not to allow cracks.

To do this, put a spring sheath of the appropriate diameter on the pipeline or bend the pipeline with a roller.

The ends of the pipelines must be double flared to ensure tight connections.

In the manufacture of new pipelines, cut off their ends strictly perpendicularly, it is best with a pipe cutter so as not to crush them. Thoroughly clean the burrs on the ends along the outer and inner diameters.

Rinse the inner walls of new brake lines with pure alcohol.

Brake flex hosereplace if scratched or otherwise damaged.

When replacing the brake hose, unscrew the connecting nut of the pipeline suitable for it, then unscrew the hose fastening nut on the frame and then unscrew it from the wheel cylinder or tee on the rear axle.

Install the hose in reverse order.

When tightening the hose nut or pipe connecting nut, hold the hose with a wrench to prevent it from turning.

The hose must not touch any parts of the chassis.