In order to understand how to use a differential lock in certain driving situations, you need to understand the structure and operation of the vehicle’s transmission elements.
The Toyota Prado 90 uses a permanent all-wheel drive system with the installation of 3 differentials (2 inter-axle and one inter-axle).
A differential is a mechanical device that divides the torque of the input shaft between the output shafts.
Experience of use
From my personal experience, I can advise using these blocking data as little as possible. In the first year of operation, having no experience of driving with permanent all-wheel drive, I thought that in winter it was better to use (for safety) a locking center differential. After replacing the transfer case chain, I no longer think so). Use locks only if really necessary; the Prado behaves quite steadily and confidently on public roads even without it.
If anyone could find this information useful, please share it on social media. networks
All-wheel drive vehicles are equipped with a unit that correctly distributes torque from the engine along the axles of the vehicle. The Prado 120 transfer case has its own characteristics, characteristics and weaknesses. During operation, transmission parts wear out, become unusable and require replacement.
- Transfer case UAZ Hunter: Design and switching
Possibility of installing a rear axle lock on the Prado 150
It is necessary to enable locks on the Prado 150 to increase the vehicle's cross-country ability. Because at the standard value of the rear axle axle there will be slipping. Especially if the road has poor grip. If the front axle is on a good surface, the wheels will not spin on it. The locking of the 121 Prado body works in the same way. The difference lies in the build quality. The 121st body is assembled in Japan, the 150th in Russia.
Thus, installing a rear axle lock allows you to eliminate slipping and ensures that the axle work is distributed evenly to all wheels.
At the same time, the designers of the Prado 150 divide the rear differential lock into two types:
- Self-locking - the axle disengages with limited slip.
- Full, otherwise – hard. On the Prado 150, the axle must be locked forcibly.
The type depends on the vehicle configuration.
Transfer case repair
To replace bearings and seals or other elements of the transfer case, it must be dismantled. To do this you need:
- Disconnect the negative terminal from the battery.
- Place the car on a viewing hole or jack it up, be sure to put stands on it.
- Remove the baffle plate.
- Drain the transmission oil from the manual transmission and automatic transmission.
- Disconnect the VSS wire connector to avoid damage when removing the box.
- Remove the transfer case shift lever from the rod.
- Disconnect all wiring harnesses from the RK.
- To provide access to the box, it is necessary to remove the exhaust system parts.
- Remove the cardan shafts. Before removal, it is recommended to mark the shaft and flange with paint - vibration may be created during assembly in a different position.
- You need to place a hydraulic stand or jack under the transfer case and secure it securely.
- Unscrew the nuts that secure the gearbox and automatic transmission.
- After making sure that all wires, vacuum and ventilation lines are removed from the box, you can begin to remove the valve body. It must be pushed back with a jack in a horizontal position until it is disconnected from the transmission.
- After the input shaft comes out, lower the box to the ground and pull it out from under the car.
After removing the RC, you need to clean it from dirt, rinse and degrease it so that no debris gets inside during disassembly. For parsing you need:
- Remove the driveshaft mounting flange.
- Unscrew the small transfer case cover. To dismantle it, it is necessary to remove the drive shaft bearing retaining ring.
- Unscrew the large housing cover.
To replace the seals, you need:
- Drain the oil.
- Unscrew the cardan from the flange and mark it with paint.
- Knock out the studs.
- Use a pry bar to move the cardan shaft to the side.
- The automatic transmission must be moved to position P (park) and the handbrake applied.
- Using a 30mm wrench, unscrew the nut and remove the flange.
- Using a screwdriver, pull out the oil seal.
- Clean the seat from dirt.
- Lubricate the new oil seal with oil.
- Take the flange as a mandrel and, with light blows of a mallet, press the oil seal into place.
- Place the flange and tighten the nut.
- Install the cardan according to the marks and screw it to the transfer case.
- Fill with high-quality transmission oil.
You can replace all components of the Land Cruiser Prado 120 transfer case with your own hands in a garage, because the price of repairs at a car service center will hit your pocket hard.
Center differential lock
If you turn on the center lock, the torque is distributed between the front and rear axles 50x50. In other words, when using this lock, the front and rear axles are simultaneously engaged, while the torque is distributed to the wheels by cross-axle differentials. A typical situation when a car stops moving when the center differential lock is turned on is when the car hangs diagonally, in this case the cross-axle lock helps.
The center differential lock can be activated while driving at speeds of up to 100 km/h. The orange indicator on the instrument panel lights up. It is used for driving on bad roads, when there is ice, for more stable vehicle behavior.
Basic transfer case malfunctions
The transfer case, like other units, requires proper maintenance. This is primarily due to the lubrication of rubbing parts. Lack of oil, contamination or poor quality product lead to rapid wear and damage to the parts in the box.
The main malfunctions of the transfer case are:
- Noisy when driving. Wear and wear of the bearing seats create play, which generates additional noise. This could also be caused by a stretched transfer case chain. To resolve these problems, it is necessary to replace worn components.
- Knocking and grinding. Similar sounds appear when a bearing fails. If you continue to use the faulty element, the transfer case will fail in a short time. It is necessary to disassemble the assembly and replace the bearings.
- Unable to turn on or difficult to turn on. This indicates damage to the gear fork or destruction of the gears. Serrations on the gears prevent them from engaging. The cause of the breakdown is rough operation of the all-wheel drive. To fix the damage, it is necessary to replace the gears and forks.
- Self-disengagement of the transmission indicates wear of the clutch, retainer or teeth on the gear. When the mechanism is turned on, incomplete engagement occurs. It is necessary to disassemble the mechanism and replace defective and worn parts.
- Overheat. If the clutch engagement servo drive fails, the unit is constantly on and overheats. To fix this, you need to replace the servo drive.
- Oil leak. When the seals wear out and the gaskets are pressed through, transmission fluid leaks. Damaged elements need to be replaced. Repair is also required if there is a crack in the housing.
- Constant crashes when turning on and off. Due to a faulty electrical part. So, due to the failure of the transfer case control unit or broken connections, there may be malfunctions in the operation of the transfer case. To eliminate such a malfunction, it is necessary to check all connections and replace unusable electronic elements.
- Jerking when moving. This signals a strong chain stretch in the RK. If these symptoms are ignored, the chain may jump off and damage the box body. To fix the problem, you need to replace it.
- Strong vibration. Worn bearings can create strong vibrations in the shafts, which causes vibration. The alignment of the transfer case relative to the gearbox may be disturbed - this is due to loosening or damage to the fastenings of the box to the body.
To correct these malfunctions, it is necessary to replace worn parts, check the balance of the cardan shafts and the reliability of fastening of all elements.
Box with low gears
The cross-country ability of the Toyota Land Cruiser 150 SUV increases significantly with downshifts. The presence of an additional box makes it possible to drive in places where cars with a classic gearbox cannot do this.
In downshifts, the wheels rotate more slowly, but the engine operates at full strength. This happens due to the presence of a transfer case (transfer case).
The car produces maximum power at a specific number of revolutions, different from the maximum power. The maximum torque is distributed by the transmission to the drive wheels.
The standard gearbox is designed for normal roads. If obstacles arise that need to be overcome (loose snow, sand, ice), in first gear the car will bury its wheels and skid. When switching to 2,3, 4 speeds, the engine will stall, as there are not enough revolutions to overcome a difficult section.
Therefore, for driving in difficult areas, SUVs are equipped with a transfer case with a low range of gears.
The transfer case reduces the speed of rotation of the wheels and at the same time allows you to spin the engine as much as possible. As a result, the SUV moves at low speed at maximum engine power. This is an indispensable feature for off-road driving, steep slopes, etc.
Transfer case repair
To replace bearings and seals or other elements of the transfer case, it must be dismantled. To do this you need:
- Disconnect the negative terminal from the battery.
- Place the car on a viewing hole or jack it up, be sure to put stands on it.
- Remove the baffle plate.
- Drain the transmission oil from the manual transmission and automatic transmission.
- Disconnect the VSS wire connector to avoid damage when removing the box.
- Remove the transfer case shift lever from the rod.
- Disconnect all wiring harnesses from the RK.
- To provide access to the box, it is necessary to remove the exhaust system parts.
- Remove the cardan shafts. Before removal, it is recommended to mark the shaft and flange with paint - vibration may be created during assembly in a different position.
- You need to place a hydraulic stand or jack under the transfer case and secure it securely.
- Unscrew the nuts that secure the gearbox and automatic transmission.
- After making sure that all wires, vacuum and ventilation lines are removed from the box, you can begin to remove the valve body. It must be pushed back with a jack in a horizontal position until it is disconnected from the transmission.
- After the input shaft comes out, lower the box to the ground and pull it out from under the car.
After removing the RC, you need to clean it from dirt, rinse and degrease it so that no debris gets inside during disassembly. For parsing you need:
- Remove the driveshaft mounting flange.
- Unscrew the small transfer case cover. To dismantle it, it is necessary to remove the drive shaft bearing retaining ring.
- Unscrew the large housing cover.
To replace the seals, you need:
- Drain the oil.
- Unscrew the cardan from the flange and mark it with paint.
- Knock out the studs.
- Use a pry bar to move the cardan shaft to the side.
- The automatic transmission must be moved to position P (park) and the handbrake applied.
- Using a 30mm wrench, unscrew the nut and remove the flange.
- Using a screwdriver, pull out the oil seal.
- Clean the seat from dirt.
- Lubricate the new oil seal with oil.
- Take the flange as a mandrel and, with light blows of a mallet, press the oil seal into place.
- Place the flange and tighten the nut.
- Install the cardan according to the marks and screw it to the transfer case.
- Fill with high-quality transmission oil.
You can replace all components of the Land Cruiser Prado 120 transfer case with your own hands in a garage, because the price of repairs at a car service center will hit your pocket hard.
Source
Cross-axle differential lock
The Prado 90 has the ability to rigidly lock the rear cross-axle differential (some models have a self-locking LSD axle). When it is locked, 3 wheels begin to rotate simultaneously, one in front and two in back.
This locking is activated using the “diff lock” lever on the instrument panel and is driven by an electric motor mounted on the rear axle.
The cross-axle differential lock can only be engaged when the vehicle is stopped and the gearbox selector is in N (neutral) position. The red indicator on the instrument panel lights up, first flashes (the locking process is in progress, you can’t move), then lights up constantly (the lock is on). It is used for driving through mud, sand, deep loose snow, for greater cross-country ability (overcoming difficult areas). Cannot be used on hard soils. Can be used with low range gears.
