Noise in the gearbox
Content
Causes noise in the gearbox depends on the type of transmission. So, in mechanical gearboxes, a rumble can appear, for example, due to wear of bearings, shaft gears, springs on the wings, differential. As for the automatic transmission, most often it buzzes due to low oil levels, problems with the torque converter and the lever wings.
To eliminate noise in the area of \uXNUMXb\uXNUMXbthe box, you should first check the oil level in it. If it is low, then you need to add or replace. As a temporary solution, an additive in the noise box is sometimes used (it will not completely remove, but at least reduce the noise of operation). To effectively eliminate the hum, the box should be dismantled, checked and fully repaired. Read about all the causes of noise in the gearbox in the article, and for a summary of why various kinds of noise appear in the gearbox, see the table.
| Conditions under which the gearbox is noisy | Possible causes of noise |
|---|---|
| Mechanical transmission | |
| Buzzing at speed (when driving) |
|
| At idle |
|
| Overclocking |
|
| When releasing the clutch |
|
| in a specific gear |
|
| In low gears (first, second) |
|
| High gears (4 or 5) |
|
| To the cold |
|
| In neutral |
|
| Automatic transmission | |
| When driving at speed |
|
| To the cold |
|
| Idle |
|
| Overclocking |
|
| in a specific gear |
|
| At low speed (up to about 40…60 km/h) |
|
Why is the gearbox noisy
Most often, noise in the gearbox, both in manual and automatic, appears when oil level has dropped or the gear lubricant is no longer usable. The nature of the sound resembles a metallic clang, which intensifies as the speed of the vehicle increases. So, noise in a gearbox with a low oil level appears:
ATF dipstick
- when the car is moving at speed (the higher the speed, the louder the clang);
- at idle speed of the internal combustion engine;
- during acceleration (there is a gradual increase in the volume of the hum);
- in neutral gear;
- when the engine is running cold.
The reason for the rumble from the gearbox when the internal combustion engine is running on a cold one can be covered in the thickness of the gear oil and its pollution.
The next common reason why the gearbox is buzzing is a partial failure of the bearings of the primary or secondary shafts. In this case, the sound will resemble a metallic hum. Primary (drive) shaft bearings will hum in the following situations:
- immediately after starting the internal combustion engine on a cold one;
- when the internal combustion engine is running at low speeds (at the first, second, then the hum decreases);
- when driving a car coasting;
- when the engine is running at high speeds.
In case of failure of the bearings of the secondary (driven) shaft box hum will be observed:
Bearing of the input shaft of the gearbox VAZ-2110
- when driving a car in any modes;
- in motion, however, when the clutch is depressed, the hum disappears;
- the hum in the box increases as the gear and speed increase (that is, the hum is minimal in first gear, and the loudest in fifth).
With significant wear of gears or synchronizers, a situation may also arise when the gearbox howls. The sound at the same time resembles a metallic clang, which intensifies as the engine speed increases. usually, the hum appears in one particular gear. This creates additional problems:
- gears are hard to turn on the manual transmission;
- in motion, the included speed may “fly out”, that is, the gear selector is set to the neutral position.
As for automatic transmissions, their hum can also occur due to bearing wear, low oil levels, gear wear. However, in an automatic transmission, a hum can also occur when it fails:
- friction pairs;
- individual parts of the torque converter.
What can be the noise in the gearbox
The noise from the box can be heard of a different nature, depending on the damage, it not only works with increased noise, but also howls or buzzes. Let us briefly describe the reasons why the above nodes lead to the fact that the gearbox howls and buzzes. so that you understand what to do with it and how to fix the problem.
Howling gearbox
The most common reason for a noise in the gearbox resembling a howl is an old, dirty or incorrectly selected transmission oil. If its level is insufficient, then as a result of this, the bearings and other moving parts of the box will run dry, making significant noise. This is not only uncomfortable when driving, but also harmful to parts. Therefore, it is always necessary to control the oil level in the gearbox and its viscosity.
The second reason why the gearbox howls is in the wear of its bearings. They can howl due to natural wear, poor quality, a small amount of lubricant in them, or dirt that has got inside.
If the box is noisy at idle with the clutch released, in neutral gear and when the car is stationary, then most likely the bearing on the input shaft is noisy. If the box buzzes more in first or second gear, then heavy load goes to the front bearings. Accordingly, it is necessary to diagnose the input shaft bearing.
Similarly, the input shaft bearing can make noise when the car is coasting or just after starting the internal combustion engine, no matter at what speed. Often the noise disappears in this case when the clutch is depressed. The reason for this is that when the clutch is depressed, the primary does not rotate, the bearing also does not rotate, and accordingly, it does not make noise.
Worn gearbox gear
If the box is noisy in 4th or 5th gear, then in this case heavy load goes to the rear bearings, that is, the secondary shaft. These bearings can also make noise not only in high gears, but also in any, including reverse. Moreover, the hum intensifies in this case with an increase in gears (on the fifth hum it will be maximum).
Gear export — This is the third reason why the box howls. Such noise appears in two cases: slipping of the teeth and an incorrect contact patch between them. This sound is different from the noise, it is more like a metallic screech. This squeal also happens under load or during acceleration.
Often the cause of the noise is precisely the gear in case the sound appears on any one particular gear. The gearbox makes noise when driving at speed due to the banal wear of the corresponding gear on the secondary shaft. This is especially true for gearboxes with high mileage (from 300 thousand kilometers or more) as a result of significant metal production and / or low oil level in the box.
Automatic box howls
In an automatic transmission, the “culprit” of howling can be hydrotransformer. This knot is colloquially referred to as a "donut" due to its respective shape. Torque converter hums when shifting gears and at low speeds. As the driving speed increases, the noise disappears (after about 60 km/h). Additional signs also indicate the breakdown of the "donut":
- car slippage at start;
- vibration of the car when driving;
- car jerks during uniform movement;
- the appearance of a burnt smell from the automatic transmission;
- the revolutions do not rise above certain values (for example, above 2000 rpm).
In turn, breakdowns of the torque converter appear for the following reasons:
Torque converter with automatic transmission
- wear of individual friction discs, usually one or more of their pairs;
- wear or damage to blade blades;
- depressurization due to the destruction of seals;
- wear of intermediate and thrust bearings (most often between the pump and the turbine);
- breakdown of the mechanical connection with the shaft of the box;
- slip clutch failure.
You can check the torque converter yourself, without even dismantling it from the automatic transmission. But it’s better not to carry out repairs on your own, but instead delegate the diagnosis and restoration of the “donut” to qualified craftsmen.
The gearbox is buzzing
Synchronizer clutch wear the underlying cause of the rumble of the box at speed. In this case, it will be difficult to turn on any gear, and often at the same time the box is buzzing in this particular gear. If the wear is significant, the transmission may “fly out” when the car is moving. During the diagnosis, you need to pay attention to the state of the spline connection of the couplings!
If the springs in the clutch weaken or break, this can also cause noise in the gearbox. Similarly, this happens in a particular gear, in which the springs are weakened or broken.
Noisy gearbox
The gearbox of a front-wheel drive vehicle contains differential, which distributes torque between the drive wheels. Its gears also wear out over time, and accordingly begin to make metallic noise. Usually it appears smoothly, and drivers do not notice it. But it manifests itself most of all when the car is skidding. In this case, the drive wheels rotate unevenly, but with a large torque. This places a significant load on the differential, and it will fail faster.
You can indirectly check the wear of the differential by the sign when the car starts to twitch after starting off (rolling back and forth). If we exclude that the internal combustion engine is to blame for this, then you need to check the condition of the differential in the gearbox.
It happens that over time, the threaded fastening of the gearbox itself weakens. As a result, it begins to vibrate during operation. Vibration, which turns into continuous noise, appears when the car is moving and intensifies as the engine speed increases and the speed of the car as a whole increases. For diagnostics, the car must be driven into an inspection hole in order to provide access to the gearbox. If the fasteners are really loose, they need to be tightened.
Noise box additives
Additives for reduction of noise of transmission allow to reduce a rumble at its work for some time. In this case, the cause of the hum will not be eliminated. Therefore, additives should be used only for preventive purposes or during pre-sale preparation of a car in order to get rid of it as soon as possible.
Different types of additives are suitable for different problems, so when choosing it it is important to determine exactly what is buzzing in the box. The most popular nozzles for reducing noise in mechanical transmissions are:
- Liqui Moly gear oil additive. Forms a protective film on the surface of parts due to molybdenum disulfide, and also fills microcracks. Well reduces noise in the manual transmission, extends the life of the transmission.
- Stainless steel Master TR3 и TR5 are designed for optimal heat dissipation in case of constant overheating of the unit. Which also helps to reduce noise in the box.
- HADO 1Stage. This additive can be used in any transmissions - mechanical, automatic and robotic. It contains boron nitride. Removes noise and vibration in the gearbox. Allows you to get to the workshop in case of a critical loss of oil in the gearbox.
There are similar additives in automatic transmissions. Examples for automatic transmissions are:
- Liquid Moly ATF Additive. Complex additive. Removes noise and vibration, eliminates shocks when shifting gears, restores rubber and plastic parts of the transmission. Can be used with ATF Dexron II and ATF Dexron III fluids.
- Tribotechnical composition Suprotec. Can be used with both automatic transmissions and CVTs. The additive is restorative, including removing vibration and noise in automatic transmissions.
- XADO Revitalizing EX120. This is a revitalizant for the restoration of automatic transmissions and transmission oil. Eliminates shocks when shifting gears, eliminates vibration and noise.
The additive market is constantly replenished with new formulations to replace the old ones. Therefore, the lists in this case are far from complete.
Hack and predictor Aviator
Most often, a manual transmission is noisy due to a low oil level in it, or it is not suitable for viscosity or is old. Second is bearing wear. Less often - wear of gears, couplings. As for the automatic transmission, similarly, most often the cause of the hum is a low oil level, wear of gears and bearings, and malfunctions of the hydraulic system elements. Therefore, the first thing to do when a howl or noise of a different nature appears is to check the oil level, and then look at the situation, under what conditions it appears, how big the noise is, and so on.
Be that as it may, it is not recommended to operate any transmission that makes a hum or shows other signs of failure. In this case, the box also wears out more and it will cost more to repair it. The exact cause can only be found out when disassembling and troubleshooting the assembly.
