Diagnostic checkpoint: ways and methods of troubleshooting

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

The gearbox is one of the most important components in any car, but paradoxically, the gearbox is an often overlooked 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 is diagnosed and how to repair the box. This information will be useful for every driver.

Checkpoint – how and why

We will not analyze the device and the principle of operation of the gearbox in great detail, but to understand it, you need to get a little familiar with the principles of this mechanism.

The main task of the gearbox is the transfer 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 leading pair of wheels with an increase in torque.

This principle is very similar to a modern bicycle. To start, they use a small sprocket, after accelerating to a certain speed, they switch to the next gear, where the gears have a different gear ratio - a smaller one to drive fast, but with less effort or speed. Switching can be 4, 5 or more.

The process of transferring torque in the gearbox is carried out by engaging gears mounted on shafts. Now there are two-shaft gearboxes, three-shaft ones. The first have primary and secondary shafts. And the torque goes from the primary shaft to the secondary through an intermediate one. The gears on them are constantly engaged. But pairs of gears, except for the one that is currently working, rotate without load. To select a pair of gears, there is a synchronizer. With the help of the gearshift lever, by means of a shift fork and synchronizers, one or another gear is connected to the one installed on the driven shaft.

Types of faults in mechanical transmissions

Before trying to diagnose the gearbox, you need to find out what malfunctions can happen to this node. Due to the structure of the breakdown mechanism, they have features. They are divided into breakdowns of the box and malfunctions of the switching mechanism.

In order to quickly and cost-effectively restore the operation of the checkpoint, you need to be able to detect breakdowns in time and know the basic solutions. This is especially important if the gearbox breaks down somewhere along the way on the highway.

Today there are robotic gearboxes. There are much more malfunctions of these boxes, and gearbox diagnostics"robot" is carried out using the built-in diagnostic system or using a PC with special software.

How to identify a broken gearbox?

Among the most common malfunctions of mechanical transmissions, one can distinguish the presence of extraneous sounds when the gear is set to neutral, noise with any gear engaged, and difficulty shifting. Also, the transmission can turn off by itself. The most common malfunction is an oil leak.

To diagnose a gearbox - VAZ or any other car - you need to understand the causes of malfunctions. There are several. Let's consider each breakdown in detail.

Noise in neutral

Characteristic noise from the transmission side with the gear selector in neutral indicates that there is increased wear on the bearings mounted on the input shaft. Also, the cause of the noise may be a low oil level in the gearbox. Oil, too, may already lose its characteristics.

Diagnosis of a car's gearbox in this case comes down to checking the oil level. For a more complete check, you will have to dismantle the box, disassemble, followed by 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 blocking elements, poor stability of threaded connections, wear of synchronizers, and incomplete clutch release are usually detected. It is best to start diagnosing a checkpointwith a clutch test. If there is an incomplete squeeze, then they try to set up the node or change the basket and disk. It is also worth making sure that there is oil in the gearbox housing and its level is in perfect order. If there is not enough oil, then it is added. If it is of poor quality, then it is changed. Then they try to shift gears with the engine running.

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, for example, during the diagnosis of the VAZ-2107 gearbox, it turned out that the synchronizers are faulty, then the gap between the gears and the blocking rings is changed. You also need to make sure that the gears do not have any damage.

Noise during gearbox operation

If a loud noise or howl is heard during the operation of the gearbox, this indicates that the gears have excessive wear. Also, the reason may be increased wear of synchronizers or bearings. In order to accurately find out 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 indicates a big and serious problem - the gears are defective or the shaft bearings are worn.

Often the noise can be eliminated by adding oil. Usually, the oil in the checkpoint is checked very rarely and they forget to add it. If there are streaks on the case, then it is better to check the level. Worn parts are replaced with new ones. Noise during operation of the VAZ gearbox is the norm even for a new car. So it's not worth itpanic.

Difficulty switching

In this case, when diagnosing the gearbox, you need to check if the clutch cable is loose. Sometimes there are difficulties with switching precisely because of the incomplete disengagement of the clutch. Another difficulty is the wear of the rod in the shift mechanism.

For better gear shifting, it is recommended to make sure the clutch is fully disengaged. Also check if there is any jamming of the gears during their movement. Conduct a thorough inspection of the gear selector system.

Shift lever is tight

It also happens that the selector lever is very tight, and you have to apply excessive force to shift. It all lies in the fact that there is not enough oil in the gearbox - it is the oil that is responsible for how smoothly the box will work. To fix the problem, you need to check the level and top up if it is insufficient.

Conclusion

As you can see, the diagnosis and repair of gearboxes are more complex than work 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 assembly. Most problems can be corrected by adding oil and replacing worn parts.