Preparation for disassembly
Before disassembly, we wash and clean the gearbox.
We drain the oil from the gearbox.
To perform the work you will need: screwdrivers (two), interchangeable sockets «13», «17», extension bar, ratchet handle, wrenches «10», «13» (two), «17», «19», «30», impact screwdriver, circlip remover, hammer, universal pullers.
We remove the flexible coupling flange from the nose of the gearbox output shaft.
See the article for the disassembly and assembly of the gearbox gear selection mechanism — «Disassembly of the gearbox gear selection mechanism».
We install the gearbox with the clutch housing on the workbench.
Removing the lower cover
Using the «10» socket, we unscrew ten nuts securing the lower cover of the gearbox.
We remove the cover.
We remove the sealing gasket.
Removing the rear cover
With a screwdriver, through the opening of the gear selection mechanism, we shift the rod of the I–II gear shift fork downwards (the II gear is engaged).
Using the «13» wrench, we unscrew the nut securing the rear cover, located inside the gearbox housing.
Using the «13» wrench, we unscrew the five nuts securing the rear cover, located outside the housing.
We tap the lugs of the cover with a hammer, while holding the rear bearing on the output shaft with a screwdriver (or a suitable pipe section when the output shaft oil seal is removed).
We shift the cover off the studs and remove it, turning it clockwise (when viewed from the tail end of the output shaft), to prevent the cover from catching on the rods and the V gear and reverse gear cluster.
We remove the cover gasket.
Removing the bearing of the V gear and reverse gear cluster
To replace the bearing of the V gear and reverse gear cluster, we pry up the bearing rollers with a screwdriver and remove the rollers from the cage.
We remove the cage.
We pry up the outer ring of the bearing with a hook.
We remove the bearing from the seat of the rear cover.
Removing the output shaft bearings
We remove the thrust ring of the rear output shaft bearing.
We remove the outer ring of the bearing with the cage and rollers.
We remove the inner ring of the bearing.
We remove the spacer sleeve.
We remove the oil deflector washer.
Locking the shafts and removing the V gear and reverse gear cluster
To lock the shafts against turning, two gears must be engaged. The II gear was engaged when removing the rear cover.
Before engaging reverse or V gear, we release the shift fork of these gears.
To do this, using the «10» wrench, we unscrew the bolt securing the fork to the rod.
Pressing the fork down with a screwdriver, we engage reverse gear.
Using a box-end wrench (socket) «17», we unscrew the bolt securing the V gear and reverse gear cluster.
We remove the bolt.
We remove the gear cluster from the splines of the intermediate shaft.
Disassembling the V gear and reverse gear cluster
We clamp the V gear and reverse gear cluster in a vise with soft metal jaw inserts.
With two screwdrivers, we press off the inner ring of the gear cluster bearing.
We remove the inner ring.
We remove the bushing of the V gear.
We remove the gear itself together with the synchronizer blocking ring.
We remove the hub.
We remove the synchronizer sleeve.
Turning the V gear and reverse gear shift fork on the rod towards the output shaft, we remove the reverse gear intermediate gear.
Removing the detent cover and the rods
Using the «13» box-end wrench, we unscrew the two bolts securing the detent cover.
We remove the cover and the gasket.
We remove the detent springs (the spring of the V gear and reverse gear rod is longer than the other two and has a dark-coloured coating).
With a magnetized screwdriver, we remove all three detents.
We remove the V gear and reverse gear shift rod together with the fork.
We remove the fork from the rod.
With a magnetized screwdriver, we remove the blocking key from the opening of the gearbox housing, located between the housing seats for the V gear and reverse gear and III–IV gear rods.
We remove the reverse gear driven gear from the output shaft.
We remove the key from the shaft groove.
Removing the III–IV and I–II gear rods
Using the «10» socket, we unscrew the bolt securing the III–IV gear shift fork to the rod.
We remove the rod.
A blocking key is inserted into the opening of the rod; we remove it.
With a magnetized screwdriver, we remove the blocking key from the opening of the gearbox housing.
The opening is located between the housing seats for the I–II and III and IV gear rods (this key is noticeably longer than the key located between the V gear — reverse gear rod and the III–IV gear rod).
Using the «10» socket, we unscrew the bolt securing the I–II gear shift fork to the rod.
We remove the rod.
Removing the retaining plate and the reverse gear intermediate gear axle
With an impact screwdriver with a Phillips tip, we unscrew the three screws securing the retaining plate of the output shaft intermediate bearing.
The screws are secured with special washers.
We remove the retaining plate.
Using the «19» box-end wrench, we unscrew the nut securing the reverse gear intermediate gear axle, holding the axle from turning with the «24» wrench.
We remove the reverse gear intermediate gear axle.
Separating the clutch housing and the gearbox housing
Having unscrewed the nuts securing the clutch housing, we separate the clutch housing and the gearbox housing.
We remove the gasket.
We remove the spring washer with a conical surface from the input shaft (with its smaller diameter facing the bearing).
Removing the intermediate shaft bearings
We clamp the splined part of the input shaft in a vise with soft metal jaw inserts.
Using the «19» box-end wrench, we unscrew the bolt of the clamping washer of the front intermediate shaft bearing.
We remove the bearing clamping washer.
With two screwdrivers, we pry up the front double-row intermediate shaft bearing by the mounting ring.
We remove the bearing. When removing the bearing, its rear inner ring may remain on the shaft.
With two screwdrivers, we press off the rear inner ring of the bearing and remove it.
We remove the thrust ring of the rear intermediate shaft bearing.
Inserting a screwdriver between the ends of the bearing and the I gear of the intermediate shaft, we shift the rear bearing.
We remove the outer ring of the bearing with the cage and rollers.
We remove the inner ring of the bearing from the shaft nose.
We shift the intermediate shaft backwards.
We remove the intermediate shaft from the gearbox housing.
Removing the input and output shafts
We pry up with two screwdrivers by the mounting ring the rear bearing of the input shaft.
We remove the input shaft together with the bearing and the synchronizer blocking ring.
We remove the needle bearing from the front nose of the output shaft.
We remove the I and II, III and IV gear shift forks.
With two screwdrivers, we pry up by the mounting ring the output shaft intermediate bearing and remove it.
Tilting it, we remove the output shaft together with the gears, sleeves, hubs and synchronizer blocking rings from the gearbox housing.
Assembling the gearbox
We perform the gearbox assembly in the reverse order.
If, when removing the front double-row intermediate shaft bearing, its rear inner ring remained on the shaft, the bearing must be assembled before installation.
To do this, using a screwdriver, we carefully remove the cage with balls from the bearing outer ring and place it on the inner ring (removed from the shaft).
We insert the cage with balls and the inner ring into the bearing outer ring.
When assembling the input shaft, using a suitable pipe section, we press the bearing onto the shaft, resting on its inner ring.
After installing the output and intermediate shafts into the gearbox housing, we press in the front and rear intermediate shaft bearings, the output shaft intermediate bearing and the inner ring of the gear cluster bearing.
We press the outer ring of the V gear and reverse gear cluster bearing into the seat of the rear cover using a socket of a suitable size (pipe section).
We insert the cage and rollers into the bearing outer ring.
To prevent the bolt securing the V gear and reverse gear cluster from loosening, we apply thread locking compound to the bolt thread.
For convenient installation of the rear cover, we install the rear bearing assembly on the output shaft.
It is advisable to lubricate all sealing gaskets with a thin layer of silicone sealant.
When assembling the gear selection mechanism, we apply Litol-24 grease to the ball joint.
The gearbox assembly technology and fault assessment are described in the article — «Gearbox assembly technology».
See the article for the disassembly of the input and output shafts — «Disassembly of the gearbox shafts».
Materials and tools used
- Screwdrivers (two), including a magnetized screwdriver — for prying up rings and removing detents and keys.
- Interchangeable sockets «10», «13», «17», extension bar, ratchet handle — for unscrewing nuts and bolts.
- Wrenches «10», «13» (two), «17», «19», «24», «30» — for unscrewing nuts and bolts of various fasteners.
- Impact screwdriver with a Phillips tip — for unscrewing the retaining plate screws.
- Circlip remover — for removing retaining and mounting rings.
- Hammer — for tapping the cover lugs.
- Universal pullers — for pressing off bearings and rings.
- Vise with soft metal jaw inserts — for clamping the gear cluster and the splined part of the input shaft.
- Pipe section — for pressing on bearings and holding the bearing when removing the cover.
- Thread locking compound — for the bolt securing the V gear and reverse gear cluster.
- Silicone sealant — for the sealing gaskets.
- Litol-24 grease — for the ball joint of the gear selection mechanism.
- New gaskets, retaining and mounting rings, bearings, oil seals — replacement parts in case of wear.