The transfer box VAZ-2123 is designed to change the amount of torque and distribute it between the front and rear axles.
The transfer case has two gears with gear ratios of 1.20 and 2.135.
The parts of the transfer case are cast from aluminum alloy and are interconnected with studs and nuts. A hatch is made in the upper part of the crankcase, closed with a stamped steel cover.
The front cover is centered on the crankcase by two dowel pins.
There are cardboard gaskets between the covers and the crankcase (when repairing, you can use sealant - gasket instead).
All shafts are sealed with rubber-metal cuffs (oil seals).
The shaft of the speed sensor drive, the shafts of the shift forks and the differential lock are sealed with rubber rings.
There are two holes in the front cover - a filler (it is also a control) and a drain.
Driven transfer case: 1 - differential lock clutch fork; 2 - differential lock fork rod; 3 - protective cover of the rod; 4 - lock washer; 5 - bushing of the lever axis; 6 - axis of the lever; 7 - differential lock lever; 8 - fork locking bolt; 9 - switch of a control lamp of blocking of differential; 10 - a rod of a fork of a gear change; 11 - thrust of the differential lock lever; 12 - fork bracket of the control lever; 13 - control lever; 14 - fork of the gear shift clutch; 15 - remote bushing; 16 - spring and retainer ball; 17 - latch spring bushing; 13 - flange of the drive shaft; 19 - front cover; 20 - drive shaft seal; 21 - bearing thrust ring; 22 - front bearing of the drive shaft; 23 - gear of the highest gear; 24 - gear shift clutch; 25 - transfer case housing; 26 - low gear; 27 - rear bearing of the drive shaft; 23 - adjusting ring of the rear bearing of the drive shaft; 29 - drive shaft; 30 - bushing; 31 - hub; 32 - back cover; 33 - rear bearing of the intermediate shaft; 34 - intermediate shaft; 35 - rear differential bearing; 36 - bearing of the rear axle drive shaft; 37 - flange; 33 - rear axle drive shaft seal; 39 - rear differential housing; 40 - gear support washer; 41 - rear axle drive gear; 42 - axis of the satellites; 43 - retaining ring; 44 spring washer; 45 - side suspension bracket; 46 - satellite thrust washer; 47 - front axle drive housing; 48 - satellite; 49 - differential driven gear; 50 - front differential housing; 51 - retaining ring; 52 - spring washer; 53 - front bearing of the differential housing; 54 - differential lock clutch; 55 - adjusting ring of the front bearing of the differential; 56 - oil deflector; 57 - front axle drive shaft seal; 58 - front axle drive shaft bearing; 59 - front axle drive shaft; 60 - flange of the front axle drive shaft; 61 - oil drain plug; 62 - driven gear of the speed sensor drive; 63 - intermediate shaft roller bearing; 64 - drive gear of the speed sensor drive; 65 - filler plug
The drive shaft is mounted on two ball bearings, the outer rings of which are located in the sockets of the front cover and crankcase.
The front bearing inner race is clamped between the shaft shoulder and the thrust washer by a self-locking shaft flange nut.
The inner ring of the rear bearing is sandwiched between the shoulder of the shaft and the thrust washer, located halfway through the nut of the rear end of the shaft.
The nut is locked by pressing its edge into the grooves on the shaft.
The drive shaft is fixed against axial displacement by a set ring in a groove on the outer ring of the rear bearing, sandwiched between the crankcase and the rear cover. There are two drive gears on the drive shaft.
The front (large) is the highest gear, it rotates freely on a heat-treated shaft neck.
Rear (smaller) - low gear, rotates freely on a heat-treated bushing mounted on the shaft with an interference fit.
Gears have two rims.
The helical (large) rims are in constant engagement with the corresponding countershaft gears, and the gearshift clutch is connected to the spur (small) rims when the gear is engaged.
The clutch moves along a hub rigidly fitted on the splines of the shaft between the drive gears.
In the middle position of the clutch, both gears are off ("neutral") and the torque from the engine is not transmitted to the wheels.
The intermediate shaft is a block of two helical gears that are in constant mesh with the gears of the input shaft.
The front gear is also in mesh with the driven gear mounted on the differential housing.
the intermediate shaft rotates in two bearings: the front one is roller bearing, the rear one is ball bearing.
The shaft is fixed against axial displacement by a set ring in the groove of the outer ring of the rear bearing, which is sandwiched between the crankcase and the rear cover (same as for the drive shaft).
A steel drive gear of the speed sensor drive is pressed into the front end of the shaft.
The driven gear is plastic, mounted on a roller rotating in the sleeve of the speed sensor drive housing.
The housing is attached to the front cover of the transfer case.
View of the rear side of the transfer case: 1 - left suspension bracket; 2 - cross member of the rear suspension bracket; 3 - rear propeller shaft; 4 - rear cover of the transfer case; 5 - front driveshaft
The front end of the front axle drive shaft rests on a ball bearing in the front axle drive housing.
The front axle drive housing is mounted on the front cover of the transfer case.
The bearing inner race is clamped between the shaft shoulder and the thrust washer by a self-locking shaft flange nut.
The bearing is fixed against axial displacement by a retaining ring, which is included in the groove of the front axle drive housing.
The rear splined end of the shaft is connected to the drive gear of the front differential axle.
A spur gear on the shaft is used to lock the differential.
The design and installation of the rear axle drive shaft is similar, but there is no gear on it.
The differential housing is made detachable, both parts are connected by six bolts.
These same bolts secure the driven gear to the differential housing.
The differential housing is mounted on two ball bearings.
The inner ring of the front bearing is kept from moving by a spacer spring washer resting on a retaining ring in the groove of the differential housing.
The groove on the outer race of the bearing includes a set ring sandwiched between the transfer box front cover and the front axle drive housing.
Thus, the differential housing is held against axial displacement by the front bearing; the rear bearing is not fixed.
On the front of the differential housing there are slots along which the lock-up clutch moves.
When the lock is engaged, the clutch connects to the gear on the front axle drive shaft, connecting it to the differential housing.
View of the front side of the transfer case: 1 - right suspension bracket; 2 - filler plug; 3 - intermediate shaft; 4 - speed sensor; 5 - speed sensor drive housing, 6 - front propeller shaft; 7 - front axle drive housing cover; 8 - left suspension bracket; 9 - rear driveshaft; 10 - front cover of the transfer case, 11 - transfer case housing; 12 - drain plug
In the holes of the differential housing there is an axle of the pinion gears held by two retaining rings.
Under one of the rings there is a spring washer that prevents axial movement of the axis of the satellites.
The satellites (bevel gears) located on the axle are in constant engagement with the axle drive gears.
Back-up washers are installed between the differential housing and pinion gears.
Their thickness is selected so that the axial clearance of the axle drive gears does not exceed 0.10 mm, and the moment of resistance to rotation is 14.7 Nm.
Control of the transfer case is manual, with a mechanical lever drive.
The driver shifts gears and engages the differential lock with one lever.
The lower end of the lever is connected to the gearshift rod, and through the rod connected to the lever axis, to the differential lock rod.
The other end of each rod is connected to the fork of the corresponding clutch (gear shift or differential lock), and this connection is locked with a bolt.
Each rod at the outlet of the box is sealed and protected from dust by a rubber corrugated cover.
To fix the actuator in the selected position, a ball detent is used - a spring-loaded ball enters the grooves on the rods.
There are three of them on the gearshift rod - for "neutral", higher and lower gears, on the differential lock rod - two ("on" and "off").
A switch is screwed into the cover of the front axle drive, which closes the control lamp circuit when the differential lock is engaged.
Possible malfunctions of the transfer case VAZ-2123
Ra vibration transfer box and body floor (in the area of the front seats) in all driving modes
Failure of intermediate shaft flexible coupling - Replace flexible coupling
Vibration of the transfer case and body floor (in the area of the front seats) when starting the car from a stop and accelerating to 80 km/h
Loose or damaged transfer box mountings and rear powertrain mounting - Tighten nuts and mounting bolt, replace damaged mountings
Tight rotation or binding in one of the planes of the hinges of the front or rear driveshafts - Repair the universal joints or replace the joints in the assembly
Incomplete release of the parking brake - Adjust the parking brake actuator
Tight rotation of the intermediate shaft constant velocity joint - Check the condition of the boot and the joint. If the hinge parts are worn or damaged, replace the hinge assembly
Vibration of the transfer case and body floor (in the area of the front seats) in the steady state of motion (most typical at a speed of 80-90 km/h)
Increased cardan shaft imbalance - Repair or replace cardan shafts
Increased unbalance of the center differential of the transfer case - Replace the center differential
Front or rear driveshaft universal joints sticking - Repair the joints or replace the driveshaft assemblies
Intermediate shaft CV joint sticking - Check boot and joint condition. If parts are damaged, the hinge must be replaced
Loose engine mount nuts and bolts or damaged engine mounts - Tighten mount nuts and bolts or replace mounts
Bent bolts and jackshaft flexible coupling flange - Replace bolts or jackshaft
Difficulty shifting or differential lock
Couplings sticking on the splines of the hub, differential housing, front axle drive shafts - Clean burrs, nicks or scuffs, replace damaged parts
Nicks on the teeth of the small ring gears of high or low gears, as well as on the teeth of the couplings and on the splines of the front axle drive shaft - Clean out the nicks and burrs, replace damaged parts
Difficulty shifting or differential lock
Couplings sticking on the splines of the hub, differential housing, front axle drive shafts - Clean burrs, nicks or scuffs, replace damaged parts
Nicks on the teeth of the small ring gears of high or low gears, as well as on the teeth of the couplings and on the splines of the front axle drive shaft - Clean out the nicks and burrs, replace damaged parts
Bent yoke or stem - Straighten deformed parts
Drive lever sticking to the axles - Remove the drive lever, clean the axles and bushings. Replace damaged parts. Lubricate the parts with lithol
Contamination or corrosion in the control joints - Clean parts, replace damaged ones
Spontaneous disengagement of gears or differential lock
Worn gear teeth and clutches - Replace worn parts
Reduced detent springs or worn detent parts - Replace springs or worn parts
Incomplete engagement of gears and lack of differential lock due to deformation of drive parts or due to nicks on gears, couplings and splines - Straighten or replace deformed parts, clean nicks and burrs, replace damaged parts
Oil leak
Damaged gaskets - Replace gaskets
Loosen the nuts and studs securing the covers to the crankcase - Tighten the nuts and studs
Worn or damaged shaft seals - Replace seals
O-rings worn on transfer case drive rods - Replace O-rings
Bells, porosity and damaged surfaces of body parts - Replace body parts