The transfer case (Fig. 1) has two gears: forward and lower

In order to reduce the amount of work in operation, ball bearings are used in the transfer case, which do not require adjustments.

Transfer case GAZ-66

The transfer case is controlled by two levers. The left lever is used to turn on the front axle and has two positions: front - the axle is on and rear - the axle is off.

The right lever is used to shift gears in the transfer case and has three positions: forward - direct gear is engaged; neutral (middle) position and reverse - downshift is engaged.

The gear shift mechanism of the transfer case is equipped with a locking device that excludes the possibility of engaging a lower gear when the front axle is off, as well as disengaging the front axle when the lower gear is engaged.

The locking device protects the driveline and rear axle parts from overload.

Transfer box maintenance

Care for the transfer case during operation consists in checking the attachment, maintaining the required level of lubrication and periodically changing the oil in the crankcase.

In some cases, troubleshooting requires removing the transfer case from the car and disassembling it.

Depending on the nature of the malfunction, disassembly can be partial or complete

Distribution box malfunctions and solutions

- Causes of malfunction


Increased noise during operation of transfer case:

- Increased lateral clearance in the engagement of gears as a result of wear on their teeth

Replace worn gears

- Weak tightening of the bolts for fastening the bearing caps and nuts for fastening the cardan flanges

Tighten bolts and nuts

- Violation of the correct gear engagement due to bearing wear

Replace worn bearings

Difficult shifting gears:

- Unequal pressure in the tires of the front and rear wheels. At the same time, the front axle does not turn on while the car is moving

Align tire pressure

- Jamming in the transfer case control drive, which may be due to bending or wear of drive parts

Check the condition of the drive and replace unsuitable parts

- Crushing, chipping at the ends of the teeth of the included gears, which appeared as a result of their frequent inclusion with noise and shock

Replace bad gears

- Jamming in the splines of the drive and intermediate shafts with sliding gears

Replace defective parts

Self disengagement of gears when driving:

- Incorrect engagement of gears, which did not ensure full engagement of the gear teeth due to high wear of the forks and rods, as well as as a result of loosening the fastening of the forks on the rods

Replace worn stems and forks, ensuring the required fastening of the forks on the stems

- Misalignment of gear teeth caused by wear of the following parts: forks and rods (no fixation is felt when shifting gears); grooves for forks and splines on the gears for engaging the rear and front axles; transfer case shaft bearings

Replace worn parts and tighten bolts.

When installing new parts, special attention must be paid to ensuring that the sliding gears are firmly seated on the drive and intermediate shafts.

In this case, the shafts and sliding gears should be selected so that there is no perceptible angular play of the gears when they slide freely along the splines of both shafts

- Axial movement of the transfer case shafts, as a result of loosening the bolts securing the bearing caps, which secure the shafts from axial movements.

Tighten the bolts

Oil leak from crankcase transfer box:

- Wear of oil seals and flange surfaces on which oil seals work

Replace worn parts

- Wear of oil seals on rods

Tighten gland nuts

- Weak tightening of the bolts securing the covers of the transfer case

Tighten the bolts

- Cracks in the crankcase and covers, damage to gaskets

Replace unusable parts

- Unsatisfactory operation of the breather (contamination with dirt)

Clean the breather of dirt or replace it with a new one

Premature wear or destruction of transfer case bearings:

- Disbalance of cardan shafts

Check cardan shaft balance and condition of cardan connections

- Weak tightening of the bolts bearing cap seals

Tighten the bearing cap bolts

Retaining half rings falling outintermediate shaft:

- Unsatisfactory shaft assembly

Correctly assemble the shaft

Removing the transfer case from the car

Disconnect from the rods of the transfer case control levers. Disconnect the horizontal handbrake link from the lever.

Disconnect the intermediate cardan shaft, the front axle drive shaft and the rear axle drive cardan shaft, remove the transfer case.

Disassembling the transfer case

Remove the central brake drum from the driven shaft flange.

Remove and unscrew the nut of the driven shaft flange, remove the flange and the central brake.

Remove the upper hatch cover and remove the retainer balls with springs from the holes.

Unscrew the plug from the hole for the locking sliders. Remove the shift rods, plugs and sliders of the rod blocking device with a spring from the crankcase.

Unscrew the stuffing box nuts from the crankcase, remove the sealing rings, washers and stuffing boxes.

Remove the stem caps.

Punch out and remove the driveshaft flange nut. Remove the flange and ball bearing cap of the input shaft.

Remove the drive shaft with the bearing assembly and the gear for engaging the rear axle and downshift from the crankcase.

Unscrew the speedometer drive driven gear fitting from the output shaft bearing cover and remove the latter from the cover.

Removing the rear bearing from the driven shaft of the GAZ-66 transfer case

Remove the bearing cover of the driven shaft, remove the rear ball bearing from the driven shaft (Fig. 2) and the speedometer drive gear.

Remove the retaining ring from the groove on the outer race of the front ball bearing of the driven shaft and remove the driven shaft assembly with the bearing from the crankcase through the side hatch.

Remove the intermediate shaft covers.

Remove and unscrew the nut securing the intermediate shaft front bearing and remove the retaining half rings from the intermediate shaft.

Compress the intermediate shaft front bearing, remove the thrust washer (some vehicles do not have a thrust washer).

Remove the intermediate shaft assembly with the rear bearing and the gears for engaging the front axle and downshift.

Remove the nut securing the drive shaft flange to the front axle.

Remove the drive shaft covers to the front axle.

Remove and unscrew the nut securing the rear ball bearing of the drive shaft to the front axle and press the bearing.

Remove the drive shaft to the front axle and gear from the crankcase.

Compress the ball bearing of the input shaft.

Remove the snap ring from the groove of the outer race of the bearing.

Press the front ball bearing off the output shaft.

Pressing the GAZ-66 transfer case roller bearing from the driven shaft seat

Press out the roller bearing from the socket of the driven shaft (Fig. 3).

Press the driveshaft front ball bearing against the front axle.

Remove the snap ring from the groove of the outer race of the bearing.

Remove the circlip from the groove of the shaft.

Remove the intermediate shaft rear bearing.

Determination of the technical condition of the transfer case parts. Inspect all parts before assembling the transfer case.

The requirements for the technical condition of the parts of the transfer case are similar to the requirements for the parts of the gearbox.

The allowable radial clearance in the transfer case bearings and the way to check it are the same as for the gearbox bearings, with the exception of the drive shaft roller bearing, for which the allowable radial clearance is 0.06 mm when checked under a load of 5 kg.

Transfer Box Assembly

Before assembling, lubricate all parts of the transfer case to prevent scuffing during the initial period of operation.

When assembling, use only new gaskets and seals. Soak the felt rings of the selector rods in the tank with grease for gas valves.

Pressing the rear bearing onto the driven shaft of the GAZ-66 transfer case

Assemble the transfer case in the reverse order of disassembly, taking into account the following instructions.

Select the intermediate shaft and gear for engaging the front axle, as well as the drive shaft and gear for engaging the rear axle and lowering transmission for ease of movement.

After selection, the gears should easily move along the splines of the shafts from the effort of the hand, but not have a noticeable axial play.

When pressing ball bearings on the journal of the input shaft and on the front journal of the driven shaft, put the bearings with the groove outward.

When pressing the central brake lever pin into the driven shaft cover, maintain a dimension of 29.5+0.25mm from the end of the pin to the end of the boss.

Some cars do not have spacer and oil rings at the front end of the front axle drive shaft.

After mounting the drive shaft to the front axle, insert the front axle engagement gear and the downshift driven gear into the crankcase.

Insert the countershaft assembly with the rear ball bearing into the crankcase through these gears so that the threaded end of the shaft comes out of the bearing hole.

Put two locking half rings into the shaft groove, place the underdrive gear washer and press the front ball bearing into the crankcase bore and onto the shaft neck until it stops against the thrust ring.

Dip the speedometer driven gear in oil before installing.

Before installing the fitting on the shank of the driven gear of the speedometer drive, lubricate its threaded part with a thin layer of sealing paste.

Pressing into the crankcase of the rear bearing assembly with the drive transfer shaft GAZ-66

Installing the rear bearing on the driven shaft is shown in fig. 4, and in fig. 5 - pressing it into the crankcase assembly with the drive shaft.

Nuts for fastening bearings and cardan flanges to core over the grooves of the shafts.

When the rear axle and downshift engagement rod enters the rear opening of the crankcase, press the locking slider with a mandrel.

Tighten the stem gland nuts until they turn tight.

Put the assembled transfer case on a test bench, fill in oil (spindle oil at ambient temperature, or nigrol heated to 60 - 80 ° C) and check the operation of the transfer case for noise in all gears at 1500 rpm of the drive shaft in for 3-5 minutes.

When checking, there should be no noise from grazing the forks on the gears and gears on other parts.

Oil leaks from the transfer case in any place are not allowed.

After testing, drain the oil from the transfer case, remove it from the stand, unscrew the nut securing the driven shaft flange and install the central brake on the bearing cap of the driven shaft.

Then put the flange of the output shaft, the washer and nut, screw it into the groove of the shaft and screw the central brake drum to the flange with screws.

The transfer case is installed on the car in the reverse order of removal.

Adjusting the transfer case

In the transfer case, the gear shift control drive is adjusted.

The adjustment should ensure that the gears are fully engaged. The required position of the control levers is provided by adjusting the lengths of the rods.

To adjust the position of the lever, unpin the link pin, remove it from the fork, move the rod until the required gear is fully engaged (the lock should clearly fix the position of the rod), put the lever in the position corresponding to the engaged gear, and set the required length of the link by rotating the fork.< /p>

Then, align the holes in the lever and the link fork, insert the pin, cotter it and tighten the locknut on the link.