Disassembly of a partially synchronized gearbox

Disassemble in the following order:

Remove the side cover with the shifting mechanism.

Remove the input shaft bearing cover

Turn the input shaft with the cutout towards the intermediate shaft drive gear and take out the input shaft with rollers and a synchronizer blocking ring.

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Remove the reverse gear block axle retaining screw and press the axle back while removing the reverse gear block (fig. 4).

Remove the plates securing the output shaft rear bearing.

Remove the locking ring of the synchroniser hub (fig. 5) and take the output shaft back. In this case, all gears will be removed from the shaft, and the bearing will remain on the shaft.

Unscrew the cover of the front bearing of the intermediate shaft with a special wrench.

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Unscrew the nut of the front bearing of the intermediate shaft with a special wrench and remove the intermediate shaft with the bearing back (fig. 6). In this case, the gears of the drive of the II and III gears will be removed from the shaft.

Unscrew the input shaft bearing nut, which has a left-hand thread, with a special wrench.

Remove the bearing from the input shaft using a puller (fig. 7).

Remove the intermediate shaft rear bearing with a puller. The bearing retaining bolt has a left-hand thread and is secured with a Belleville washer spring.

Disassembly of the synchronized gearbox

Disassemble in the following order:

Remove the side cover with the shifting mechanism.

Using the M8 threaded hole in the rear end of the intermediate reverse gear axle, press the axle back, remove the gear.

Remove the input shaft bearing cover.

Remove the front intermediate shaft bearing cover.

Unscrew the bolt securing the rear bearing of the intermediate shaft (the bolt has a left-hand thread) and remove the washer spring of the bolt.

Using a puller, remove the rear bearings of the input and output shafts by their retaining rings.

Remove the intermediate shaft rear bearing retaining ring.

Install the box so that the countershaft is up, move the countershaft forward until the countershaft gear block stops in the crankcase.

Bring the intermediate shaft together with the rear bearing back until the inner race of the front bearing comes out of the rollers and the rear bearing comes out of the crankcase.

Remove the intermediate shaft rear bearing with a puller.

Place the transmission with the shift hatch facing up.

Remove the input shaft, 4th gear locking ring, output shaft assembly (supporting the 1st gear spacer ring) and intermediate shaft assembly from the transaxle case.

Disassembly of the output shaft

Remove the thrust washer and the 1st gear with the needle bearing.

Remove the synchroniser hub retaining rings using a puller and a thrust washer.

Remove the synchronizer of the 1st and 2nd gears together with the gear of the 2nd gear.

Remove the circlip, key and bearing of the 2nd gear gear.

Remove the synchronizer of III and IV gears together with the gear wheel of III gear.

Remove the circlip, key, spacer sleeve and bearing for the 3rd gear.

Assembling a Synchronized Gearbox

Assemble the gearbox, starting with the subassembly of its units, in the following order:

Assembling the input shaft

Разборка и сборка КПП УАЗ-3151

Grind the locking ring on the taper of the shaft to a size of 0.8–1.25 mm, as shown in fig. 36

Press in the ball bearing with the O-ring against the stop against the bearing nut.

Screw on the bearing retaining nut (left-hand thread) and lock it by punching it into the groove in the shaft.

Apply grease to the shaft bore and insert the rollers (14 pieces).

Synchronizer assembly

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Select a set of coupling and synchronizer hub with minimum clearances for free movement according to Fig. 37 or use kits 469-1701117 and 469-1701138, selected by the manufacturer.

Put three springs (fig. 38), three guide springs, three balls and three crackers in the hub and install the clutch on the hub (the clutch of the 1st and 2nd gears is made in one piece with the reverse gear).

Install the crackers with the side with the holes of the smaller diameter towards the coupling.

Assembling the output shaft

Разборка и сборка КПП УАЗ-3151

Install the 3rd gear needle bearing, bearing spacer, circlip and key.

Grind the blocking ring of the synchroniser on the cone of the gear wheel of the 3rd gear to a size of 0.8–1.25 mm, as shown in fig. 39.

Lubricate the bearing with transmission oil, install the III gear with a locking ring, a thrust ring, install the III and IV gear synchronizer and circlip with a cut to the hub key.

Grind the synchronizer blocking rings on the cones of the 1st and 2nd gears to a size of 0.8–1.25 mm, as shown in fig. 39.

Install the 2nd gear needle bearing, circlip.

Lubricate the bearing with gear oil, install the 2nd gear with a locking ring, a thrust ring, install the 1st and 2nd gear synchronizer.

Install the thrust ring, the circlip, the 1st gear with a locking ring and a lubricated bearing, install the spacer ring (oil deflector) so that the pin of the output shaft falls into the groove of the spacer ring (oil deflector).

Install the locking collar and secure it (the locking collar will facilitate the installation of the pinion shaft assembly in the transaxle case).

Reverse gear sub-assembly with bearing

It is carried out in the same way as the assembly of the reverse gear with the gearbox bearing, partially synchronized.

The assembly of gearshift mechanisms for cars of the UAZ-31512 and UAZ-3741 family is carried out similarly to the assembly of gearshift mechanisms, partially synchronized.

Assembling the gearbox from sub-assemblies

Perform further assembly of the gearbox in the following order:

Insert the assembled intermediate shaft (with gear block, circlip and roller bearing inner race) into the transmission case.

Insert the assembled output shaft into the gearbox housing, remove the locking sleeve.

Install (press in) the output shaft rear bearing with the circlip installed on it. When pressing in the output shaft, place an emphasis on the end of the shaft journal under the synchronizer hub with a mandrel. When pressing in, pay attention to the correct installation of the thrust washer of the 1st gear.

Install (press) the assembled input shaft into the gearbox housing so that the groove for the bearing circlip is recessed into the crankcase.

Reinstall the countershaft by engaging the gears.

Install (press in) the rear bearing of the intermediate shaft with the retaining ring installed on it until the inner race of the bearing stops against the end of the shaft and the circlip at the end of the crankcase.

Install the front bearing outer race with cage and rollers onto the front end of the countershaft.

Secure the countershaft rear bearing with the Belleville washer bolt.

Correct the input shaft so that the groove for the circlip comes out of the gearbox housing, install the circlip and seat the input shaft against the stop ring in the crankcase.

Install (press in) the intermediate shaft front bearing cover until the ends of the cover and the crankcase match.

Install a gasket on the front end of the crankcase so that the cutout in it coincides with the oil drain hole.

Install the bearing cover on the input shaft so that the oil drain line is aligned with the cutout in the gasket.

Fasten the cover with four bolts and lock washers. Install the clutch release bearing take-off spring bracket under the two left-hand bolts.

Secure the pinion shaft rear bearing to the shaft using a thrust and circlip.

Insert the reverse gear shaft into the hole in the crankcase from the rear mating plane.

Insert the reverse gear into the crankcase so that the axle enters it from the side opposite to the groove for the shift fork.

Press in the reverse gear axle until it stops in the crankcase according to Fig. 40.

Разборка и сборка КПП УАЗ-3151

Assembling the gearbox from sub-assemblies

Carry out further assembly of the gearbox in the following order:

Insert the assembled countershaft into the transmission case.

From the rear, put the spacer ring, the 2nd gear gear, the 3rd gear gear and the intermediate shaft drive gear on it in sequence.

Разборка и сборка КПП УАЗ-3151

Install the shaft (fig. 31) with the bearing until the bearing ring stops in the crankcase.

Install a washer, bearing and tighten the special nut on the front end of the intermediate shaft.

Open the nut to lock it. Axial movement of gears along the shaft is not allowed.

Screw the cover with the rubber O-ring into the front hole of the crankcase, flush with the end of the crankcase.

Do not overtighten the cap to avoid damaging the o-ring.

Lubricate the journals of the II and III gears of the assembled secondary shaft with liquid oil and, inserting it from the back into the upper hole of the crankcase, successively put on it the gear of the 1st gear, the gear of the II gear, the gear of the III gear with the synchronizer ring, the thrust washer, the synchronizer assembly.

Set the pinion shaft bearing together with the shaft up to the groove in the bearing.

Secure the entire gear set with a snap ring by placing it in the groove on the front end of the pinion shaft. Gears of II and III gears should turn freely by hand.

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Secure the rear bearing (fig. 32) of the output shaft with two plates with screws.

Install the locking ring, lapped against the input shaft cone, into the synchroniser hub.

Insert the assembled input shaft into the gearbox housing with the cutout down to the intermediate shaft drive gear.

Using a mandrel, install the shaft (fig. 33) and bearing until the bearing ring stops in the crankcase.

Install a gasket on the front end of the crankcase so that the cutout in it coincides with the oil drain hole.

Install the bearing cover on the input shaft so that the oil passage of the cover aligns with the oil drain hole of the crankcase.

Разборка и сборка КПП УАЗ-3151

Secure the bearing cover (figure 34) with four bolts and lock washers.

Install the clutch release bearing take-off spring bracket under the two left-hand bolts.

Tighten the bolts with a torque of 12 to 18 Nm (1.2–1.8 kgf · m).

Lubricate the bearing of the reverse gear block with liquid grease, insert the gear block with a large rim against the hole in the crankcase and insert the axle into the block through the hole in the crankcase.

Press the pinion shaft into the crankcase so that the hole in the axle aligns with the M6 threaded hole in the crankcase wall.

Разборка и сборка КПП УАЗ-3151

Screw in the set screw flush with the plane of the crankcase connector (figure 35).

Install the shift mechanism to the transmission and secure it with bolts and lock washers.

Before installing the shift mechanism, make sure the gears in the transmission and the shift forks are in neutral.

Tighten the bolts with a torque of 12 to 18 Nm (1.2–1.8 kgf · m).

Assembly of the gearbox, partially synchronized

Assemble the gearbox, starting with the subassembly of its units, in the following order:

Assembling the input shaft

Разборка и сборка КПП УАЗ-3151

Grind the locking ring on the taper of the shaft to a size of 0.8–1.25 mm, as shown in fig. sixteen.

Install the oil deflector.

Press the ball bearing onto the shaft until it stops against the end of the oil deflector so that the groove in the outer ring of the bearing is offset away from the ring gear.

Screw on the bearing retaining nut (left-hand thread) and lock the nut by punching into the groove in the shaft.

Place the thrust washer on the ball bearing.

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Apply grease to the shaft bore and insert the rollers (14 pieces).

Insert the roller retaining ring.

Assembling the output shaft

Install the oil deflector.

Press on the double row ball bearing with the marking towards the gearbox.

Secure the bearing to the shaft with a thrust washer and circlip.

Assembling the intermediate shaft

Разборка и сборка КПП УАЗ-3151

Press the bearing against the stop on the rear end of the intermediate shaft so that the groove in the outer ring of the bearing is displaced towards the gear.

Install the Belleville washer with the bulge toward the bolt head.

Tighten the bearing retaining bolt (left-hand thread).

Place the thrust washer on the bearing.

Assembling the third gear set

Grind the synchronizer blocking ring on the cone of the gear wheel of the 3rd gear to a size of 0.8–1.25 mm, as shown in fig. sixteen.

Sub-assembly of the reverse gear block with bearing

Install the circlip into one of the two grooves in the hole in the gear block.

Place the thrust washer, bearing and one more thrust washer in the hole in sequence.

Place the circlip securely in the groove.

Synchronizer assembly

Select the set of the coupling and the synchronizer hub with the minimum clearances for free movement according to or use the set 451D – 1701116–11, selected by the manufacturer.

Разборка и сборка КПП УАЗ-3151

Разборка и сборка КПП УАЗ-3151

Place in the hub three springs (Fig. 20), three crackers, three balls and install the shift clutch on the hub.

Moreover, place the longer part of the hub towards the end of the coupling, which has a shaped chamfer (Fig. 21).

The holes in the bread crumbs are made stepped. Install the crackers on the side with the smaller holes and on the side of the sleeve.

It is possible to install whole biscuits with protruding hemispheres acting as balls into synchronizers.

Intermediate shaft cover assembly

Install the rubber ring into the groove in the cover.