The gearbox is one of the most important units in any car, but paradoxically, the gearbox is an often ignored unit. The result is usually predictable - these are various extraneous sounds, crunches when switching and other malfunctions. Let's look at what to do if something is wrong with the gearbox, how the gearbox diagnostics are performed and how to repair the box. This information will be useful for every driver.
PPC - how and why
We will not analyze in detail the device and the principle of operation of the gearbox, but for understanding you need to get a little acquainted with the principles of this mechanism.
The main task of the gearbox is the transmission of torque and power from the power unit in a variable speed range. To change this set of revolutions, pairs of gears are used that have different gear ratios - it is precisely due to this that one and a half thousand revolutions can turn into revolutions of the driving pair of wheels with an increase in torque.
This principle is very similar to a modern bike. To start, use a small asterisk, after accelerating to a certain speed, they switch to the next gear, where the gears have a different gear ratio - less to drive fast, but with less effort or speed. Switchings can be 4, 5 or more.
The process of transmitting torque in the gearbox is carried out by engagement of gears mounted on the shafts. Now there are two-shaft gearboxes, three-shaft ones. The first have primary and secondary shafts. And the rotational moment goes from the primary shaft to the secondary through the intermediate. The gears on them are constantly engaged. But pairs of gears, except the one that is currently working, rotate without load. To select a pair of gears, there is a synchronizer. Using the gearshift lever through a shift fork and synchronizers, this or that gear is connected to the gear installed on the driven shaft.
Types of mechanical transmission failures
Before trying to diagnose the transmission, you need to find out what kind of malfunctions can happen to this node. Due to the structure of the breakdown mechanism, they have features. They are divided into box breakdowns and switching mechanism malfunctions.
In order to quickly and without any cost to restore the operation of the checkpoint, you need to be able to detect breakdowns in time and know the main methods of elimination. This is especially important if the checkpoint has broken down somewhere along the way on the highway.
Now there are robotic gearboxes. There are much more malfunctions of these boxes, and the Robot checkpoint is diagnosed using the built-in diagnostic system or using a PC with special software.
How to detect a gearbox breakdown?
Among the most common malfunctions of mechanical transmissions, one can distinguish the presence of extraneous sounds with the neutral gear installed, noises with any gear engaged, difficulties with switching. Also, the transmission can be turned off independently. The most common fault is oil leakage.
To carry out the diagnostics of the checkpoint - VAZ or any other car - you need to understand the causes of malfunctions. There are several of them. We consider in detail each breakdown.
Neutral noise
The characteristic noise from the gearbox side with the gear selector in the neutral position indicates that there is increased wear on the bearings mounted on the drive shaft. Also, the cause of noise may be the low oil level in the gearbox. Oil, too, can already greatly lose its characteristics.
Diagnostics of the vehicle gearbox in this case comes down to checking the oil level. For a more complete check, you will have to perform the dismantling of the box, disassembly with subsequent troubleshooting. If bearing wear is observed, they are replaced with new ones. Spare parts for gearboxes can be purchased separately at auto parts stores.
Switching noise
Here, deformations and increased wear of locking elements, poor stability of threaded joints, wear of synchronizers, incomplete clutch release are usually revealed. It’s best to start gearbox diagnostics with a clutch check. If there is an incomplete squeeze, then try to configure the node or change the basket and disk. It is also worth making sure that there is oil in the gearbox crankcase and its level is in perfect order. If there is not enough oil, then top it up. If it is of poor quality, then it is changed. Then they try to shift gears on a wound engine.
For a more complete diagnosis, you will need to remove the gearbox and disassemble the mechanism. This is the only way to see worn or broken parts. If during, for example, the diagnostics of the VAZ-2107 checkpoint, it turned out that the synchronizers are faulty, then the gap between the gears and the locking rings is changed. You must also make sure that the gears do not have any damage.
Noise during the operation of the gearbox
If a strong noise or howl is heard during the operation of the gearbox, this indicates that the gears have excessive wear. Also, the cause may be increased wear of synchronizers or bearings. In order to accurately determine the malfunction, you need to remove and disassemble the gearbox.
Crunch and noise can be different - constant sounds or only when switching. In the first version, the sound speaks of a big and serious problem - the gears are defective or the shaft bearings are worn out.
Often the noise can be eliminated by adding oil. Typically, oil in the gearbox is checked very rarely and forget to top up. If there are leaks on the case, then it is better to check the level. Worn parts are replaced with new ones. The noise during the operation of the VAZ checkpoint is the norm even for a new car. Therefore, do not panic.
Switching difficulties
In this case, when diagnosing the gearbox, you need to check whether the clutch cable is loose. Sometimes there are difficulties with switching due to incomplete disengagement of the clutch. Still more difficult is stem wear in the gearshift mechanism.
In order to shift gears better, it is recommended to make sure that the clutch is fully disengaged. They also check if the gears are jammed during movement. A thorough inspection of the gear selection system is carried out.
Shift lever walks tight
It also happens that the selection lever walks very tight, and you have to exert excessive efforts to switch. Here everything lies in the fact that there is not enough oil in the gearbox - it is the oil that is responsible for how the box works smoothly. To eliminate the malfunction, you need to check the level and add if it is insufficient.
Conclusion
As you can see, the diagnosis and repair of the gearbox is more complicated than working with any other vehicle component. Everything is hidden in the gearbox. In order to find a breakdown and fix it, you need to remove and disassemble the unit. Most problems can be fixed by adding oil and replacing worn parts.