There is a metallic sound coming from the gearbox. How and why the “mechanics” make noise: the secrets of sounds out of the box

Manual transmissions of cars often frighten drivers with various sounds that from time to time come from the depths of an essentially simple device. As a rule, motorists themselves are to blame for their occurrence. But there are also sounds that appear for reasons beyond their control. Let’s figure out why the box “sings” and whether you should be afraid of it.

How the mechanics work

Before delving into the nature of sounds, let’s turn to the design of the gearbox and explain its structure “on the fingers”.

As you know, an internal combustion engine is not capable of transmitting maximum torque and power to the wheels of a car from idle speed. To ensure maximum performance, it needs to reach optimal speed (usually quite a lot). This can be done using a gearbox, which changes the gear ratio, thereby making life easier for the engine and giving the car high speed.

A manual gearbox is a device that allows you to change the gear ratio in steps. Essentially, this is a metal box, inside of which there are two or three parallel shafts with gears that set the rotation speed of the secondary (driven) shaft and, accordingly, the wheels of the car - through the main gear and differential. The purpose of this entire structure is to transmit torque from the engine flywheel to the wheels. By combining gears in different combinations, we get different gear ratios.

The gears of the secondary shaft are movable and connected to it using couplings that act as locks. By closing and opening the clutch, the driver connects and disconnects one or another gear. In this case, one clutch is used for two gears. This is precisely where one of the reasons for the appearance of unpleasant sounds lies.

Terrible grinding noise when shifting to the next gear

When changing gears, drivers often forget to depress the clutch or do not press the pedal all the way. After which they hear a frightening metallic clang from the box - this noise comes from gears that cannot engage with each other.

Why is this happening? When we disengage one of the clutches, the output shaft rotates at one speed, and the next gear rotates at another. To engage a gear, you need to synchronize the rotation speeds of the shaft and gear. To do this, the engine is briefly disconnected from the transmission by squeezing the clutch. When the engine is disconnected from the transmission, the speed is equalized and the clutch meshes with the gear of the next gear. Additional assistance in equalizing speeds is provided by special devices - synchronizers.

They work as follows. When selecting gears, the shift fork moves the clutch towards the gear of the selected gear. The force is transmitted through the crackers to one of the locking rings, which, together with the clutch, moves towards the engaged gear. A frictional force arises on the mating surfaces, which rotates the locking ring until it stops in the cracks. The rotation speeds of the gear and synchronizer are equalized, the gear is rigidly connected to the shaft and the gear is engaged.

Thus, when the clutch is open, the torque from the wheels, with the help of synchronizers, accelerates the secondary shaft (when shifting down) or stops the primary shaft of the box (when shifting up). Without pressing the clutch, it is difficult to achieve an exact match of rotation speeds. That is why the gears either do not turn on or turn on with a loud, unpleasant sound. In this case, the teeth do not mesh correctly and touch each other with their ridges. This puts excessive stress on the gears and can cause them to break.

This sound sometimes occurs when the clutch pedal is depressed - in this case, it sounds like a death sentence for the synchronizers: you can prepare a tidy sum to repair the gearbox.

Crunching sound when reverse gear is engaged

Drivers in a hurry often try to engage reverse gear when the car has not yet stopped and continues to roll forward. In this case, the same metallic grinding noise is heard.

The secret of these sounds is simple: reverse gear is realized using a guide idler gear, which rotates in the opposite direction. When engaging reverse gear, the splines simply cannot engage with the reverse gears. That is why it is almost impossible to engage reverse gear while driving. And the sounds from the box clearly hint that you first need to come to a complete stop, and only then engage reverse.

Howling when reversing

And now we answer the question that, sooner or later, perhaps all motorists ask: why does the car howl strangely when reversing?

And again we turn to the gearbox design. It's all about using a different type of gear for reverse gearing - one that is simpler and cheaper to manufacture. If helical gears are used for forward gears, then in reverse gears they are spur gears.

The advantage of helical gears is the ability to transmit large loads. They engage each other more smoothly and make less noise. Moreover, their conjugation spot is relatively large. But they also have a drawback: when helical gears operate, a moment arises directed along the axis. Therefore, they simply need thrust bearings. In addition, a large contact patch increases friction losses - part of the energy is spent on useless heating.

Spur gears for reverse gears can withstand lighter loads and are noisy, but they perform their tasks properly. They are cheap and do not require expensive synchronizers. Spur gears always have an almost imperceptible gap in the mating. When they operate, a continuous knocking noise occurs when the gears come into contact with each other. This creates the howling sound.

Thus, you should not pay attention to the strange howling sounds from the gearbox that occur when driving in reverse. The box is in good condition and does not require any repairs.

Often noise from sources such as tires, wheel bearings, engine, exhaust system is mistaken for transmission noise. The noise level in the cabin can vary widely, as it depends on the size of the vehicle, as well as the type and amount of sound insulation materials used. The gearbox, like any gear mechanism, is not completely silent. Therefore, the operation of a serviceable gearbox is always accompanied by slight noise. To check the noise level of the gearbox while the vehicle is running, do the following:

1) Select a section of road with a smooth asphalt surface to reduce the noise created when tires roll and the level of resonance noise in the car interior.

2) After driving the vehicle, warm up all components of the vehicle to normal operating temperature.

3) Write down the vehicle speed and the number of the gear engaged at which an increase in noise is observed.

4) Check for noise when the engine is idling and the vehicle is stationary.

5) Determine in which driving mode there is increased noise.

5a) Acceleration - smooth or sharp.

5b) Uniform movement - movement of a car at a constant speed at a small opening angle of the throttle valve on a horizontal road.

5c) Engine braking - driving a vehicle with the gear in gear and the throttle valve partially or completely closed.

5d) In all of the above modes.

Bearing noise

Final drive bearing noise can easily be confused with wheel bearing noise. Since the final drive bearings are preloaded, their noise should not be noticeably reduced when the gearbox is running and the suspended drive wheels are rotating. The characteristic feature of wheel bearing noise is that it continues when the car is coasting in neutral in the gearbox. Since the wheel bearings do not have preload, their noise is noticeably reduced when the suspended wheels rotate.

Brinelling

Brinell bearings are characterized by clicking or knocking sounds, the frequency of which is approximately half the speed of rotation of the wheel, since the rollers move more slowly.

Brinelling is a consequence of the action of large forces that press the rolling elements (balls or rollers) into the bearing ring. In this case, indentations are formed on the ring track. Brinelling is observed when the bearing ring is pressed onto the shaft journal or into the crankcase seat, if the force is applied through the race with the rolling elements and the second ring. Brinelling is also caused by vibration acting on the housing part in which the bearing or rotating shaft is installed. An external sign of brinelling is the presence of small dents on the surface of the bearing treadmill, making it look like a washboard. The operation of a defective bearing is accompanied by strong low-pitched noise.

Laping

Laping is caused by small abrasive particles of scale, sand, corundum, etc. materials that are carried by oil. These particles cause wear on the raceways and rolling elements of bearings. A defective bearing may have significant play but operate smoothly. The cause of lapping is the operation of the car on contaminated oil.

Jamming

Bearing jamming occurs when large foreign particles enter the treadmill. These particles can jam the rolling elements and cause one of the bearing rings to rotate. Excessive preload on tapered bearings can also cause them to seize.

Pitting

Pitting, or pitting of rolling surfaces, is a consequence of normal fatigue wear under prolonged exposure to cyclic contact stresses. Pitting can also be a consequence of improper installation of the bearing or develop after the introduction of solid foreign particles into contacting surfaces.

Spalling

Spalling, or scaly spalling and cracking of the rolling surfaces, is a consequence of overloading or improper installation of the bearing (misalignment, misalignment of rings or excessive preload).

Many drivers unknowingly confuse the symptoms of a manual transmission malfunction with signs of a breakdown in the gear selection mechanism or clutch. Fortunately, they require much less attention than CVTs, DSG and robotic gearboxes. But even highly reliable units eventually begin to make noise at idle, while driving, and suffer from poor gear shifting.

The transmission is noisy in neutral and howls at speed.

Main causes of malfunction:

If extraneous noise from the gearbox occurs when the clutch is depressed, the release bearing is faulty.

gear wear. The reason is the development of gear teeth at the contact points. In this case, only replacing worn parts will help eliminate noise and howling;
wear of the bearings of the driven, drive or intermediate shaft. As a result of oil starvation, heavy loads, increased torque after or natural wear, abrasions, scuffing and uneven performance appear on the rolling elements and bearing races;
production of differential parts for front-wheel drive cars. In such cases it is not uncommon.

Some VAZ models are worthy of a special note, in which the manual transmission begins to make noise, howl and vibrate at relatively short distances. Many people attribute the malfunction to a design defect and the quality of manufacturing of transmission parts, which makes the idea of any repair very doubtful.

Gears engage poorly and with a crunch

Difficulty shifting gears and a metallic grinding noise at the moment of shifting are clear signs of a malfunction of the manual transmission synchronizers. But before removing the gearbox for repairs, check the gear selector and clutch. Play in the gearshift lever, cable jamming, and incorrect adjustment of the gear selection mechanism lead to unclear and often poor gear shifting. And incomplete disengagement of the clutch after pressing the pedal () will cause crunching and grinding sounds. Driving with such a malfunction will quickly damage the synchronizers.

If your car only shifts into second or, for example, third gear with a crunch, then the problem is most likely with the synchronizers. These elements are intended to equalize the rotation speed of the output shaft and the gear engaged in the transmission. Wear of the conical friction part leads to slipping of the blocking ring and rigid engagement of the clutch with the gear teeth. When disassembling and troubleshooting, you should also pay attention to gears, gear clutches and their forks.

Knocks out the speed

The synchronizer blocking ring and gears have specially shaped teeth with which the clutch engages when changing speeds. If the coupling splines, teeth on the ring and gear are ground down, then when the load is applied and the gas pedal is released, the transmission spontaneously switches off. In this case, it will not be possible to limit yourself to replacing synchronizers; you should definitely change the gear of the damaged transmission and the gear shift clutch.

The speed will be knocked out even if it is not turned on completely. Possible causes of manual transmission malfunction:

wear of the rod, gear shift fork;
cable jamming;
incorrect installation, wear of the intermediate shaft bearing;
wear of the manual transmission cushion, which causes the box to shift under load;
loose gearbox housing bolts.

Oil leak from manual transmission

Possible causes of oil leakage:

wear of the drive shaft oil seal;
torn boot;
loose pressure of the manual transmission pan, loose inspection hole bolt.

The cause of insignificant oil consumption may be a worn out oil seal on the speed selector rod. If you notice an oil leak, be sure to check the transmission breather. If it is clogged, excess pressure inside the gearbox housing will lead to squeezing out the seals and causing oil leakage.

The inspection hole at the bottom of most units is designed to check the transmission oil level. Often, the liquid level is level or 5-10 mm below the control hole is considered normal. If the manual transmission is noisy due to lack of oil, you can add fluid through the breather. If access to the upper gearbox cover or breather is limited, you can use a special syringe to fill the gap through the control hole. You can read about what kind of transmission fluid is poured into the manual transmission and how to change it correctly in the article “When to change the oil in a manual transmission.”

Etc.).

Moreover, transmission repair is also a complex and expensive procedure. This is especially true when it comes to automatic transmissions, high-quality overhaul or overhaul of the automatic transmission. For this reason, it is important not only, but also to record any signs that indicate possible problems with the transmission and gearbox.

Next, we will talk about why extraneous sounds occur and what they indicate during gearbox operation, for what reasons the gearbox hums, what to do if a manual or automatic gearbox howls, etc.

Read in this article

The box buzzed: the main reasons

During operation, one of the most common signs of problems or breakdowns is a hum in the gearbox. In this case, gearbox noise or hum may differ in tone and strength, occur only in some or all gears, etc.

So, let's start with the automatic transmission. In this case, it is important to understand that an automatic transmission (variator, robotic mechanics, hydromechanical automatic) operates somewhat quieter than a manual transmission, and should not make obvious extraneous sounds.

If the automatic transmission hums or makes noise, first of all, you need to check its condition and quality. The box itself should also be inspected for possible transmission fluid leaks.

In a situation where the unit itself is dry, everything is also fine with the oil, or it was replaced with a separately recommended ATF, in parallel, but the hum in the box does not go away, then diagnostics are required.

As a rule, this means that the box will need to be removed and disassembled for troubleshooting, and such work is expensive if it is not carried out on its own, that is, at a specialized car service center.

As for the common causes of automatic transmission hum, experts highlight:

Manual transmissions or automatic transmissions with mileage are characterized by abrasion/damage or wear of the main pair parts. As a result, backlashes appear, which become a source of noise;
Wear of gears means that strong friction occurs in the mating area, loads increase, noise increases, the box hums;
If the CVT is humming, in some cases this is a sure sign of serious wear or malfunction, indicating that the box will soon completely fail.
In some situations, it may not be the box itself that buzzes, but the . In other words, play occurs at the mounting points of the axle shafts, resulting in a strong gearbox hum.
Let us also add that in automatic transmissions the bearings often hum and make noise; abrasion and damage to the teeth on the drive gear or on the shaft lead to the appearance of backlash and hum (both in one gear and in several).

In other words, in most cases it is impossible to operate a car with a humming automatic transmission normally. Moreover, depending on the type of gearbox, such operation may even be unsafe, since the robot clutch may open, problems with acceleration during overtaking, changing lanes in traffic and other maneuvers.

Now let's move on to the manual transmission. As is the case with an automatic transmission, the hum of a manual transmission and various noises in a manual transmission arise for various reasons. Moreover, there can be quite a lot of such reasons, starting from a lack of transmission oil and ending with defects and damage to individual parts.

At the same time, it is a mistake to believe that a manual transmission is much more reliable than an automatic transmission, that is, such a transmission can be constantly subjected to loads, the car can be used aggressively, etc. In fact, this unit may well hum or fail by 100-150 thousand km.

If we talk about repairing a manual transmission, it is much cheaper to repair a manual transmission than an automatic transmission. At the same time, high-quality repairs still require the replacement of a number of elements. Also, performance will directly depend on the qualifications of the specialists who perform the gearbox overhaul.

So, the list of reasons for a hum in a manual transmission includes:

Insufficient lubrication. If there is little oil in the gearbox, symptoms often manifest themselves in the form of the gearbox howling and humming in higher gears (for example, gearbox hum in 5th, 6th gear).

In lower gears there may be no extraneous noise. As a rule, in this case we can say that there is oil, but it is not enough. At the same time, gears and other parts of the manual transmission are subject to increased wear.

Another cause of noise is wear or defective replacement of parts of the main pair. In this case, the box may hum for a long time, but then the unit will finally break down.

Also, noise in the gearbox is caused by worn drive bearings, which first emit a hum, after which they simply collapse after a short time. As a result, you can expect serious consequences and a significant increase in the cost of repairs.

Often the cause of the hum is the gears of the gears, and only one gear of the gearbox can hum. This indicates that problems arise only with individual gears of the gear that began to hum;
It is also possible that noise may appear after repairing the box, which is due to errors during assembly (imprecise fit of the shaft and gears, etc.);
Also, what indicates malfunctions in the gear shift mechanism (gears are difficult to engage, problems have arisen with gear selection, the gearbox is worn out, malfunctions, etc.);

A hum has appeared in the gearbox: what should the driver do?

As you can see, extraneous sounds in the form of noise, gearbox hum or crunching noise can appear in both automatic and manual transmissions. Moreover, the gearbox may suddenly buzz if there is an emergency leak of transmission oil.

This means that you need to inspect the unit for leaks. If leaks are visible, then the leaks will need to be repaired. It is also optimal to stop further operation of the vehicle, that is (especially in the case of an automatic transmission).

If this is not possible, then after adding oil you should immediately take the car to a service center, avoiding stress on the gearbox. It is not recommended to use the “stop-flow” type unless absolutely necessary.

In cases where the box is dry, but there is a hum, this malfunction tends to progress. In other words, the noise will only increase with mileage. In the case of an automatic transmission, it is better not to delay and immediately go for diagnostics.

As for the mechanics, the box with the hum is in many cases operated further, avoiding high loads. It is important to understand that such operation in the future can lead to more serious consequences and increased repair costs. For example, if the main pair, gears, synchronizers, etc. are worn out, you can drive, but in this case the loads on other parts of the box are also increased.

It turns out that the best solution is to carry out timely diagnostics in a specialized gearbox repair service when any extraneous sounds appear (hum, noise, howl or gearbox crunch). Experienced specialists, if necessary, will disassemble the box, determine the cause of the problem, carry out troubleshooting and preliminarily draw up an estimate, which will indicate the amount of repairs.

Let us also add that when selecting spare parts, it is better to refuse cheap taxes, that is, use only original spare parts or high-quality substitutes from third-party manufacturers. Only in this case can you count on high-quality work and an acceptable service life of the gearbox after repair.

Causes

If the car is parked and the speed is not turned on and noise is heard when the engine is running, it means:

the input shaft bearing has worn out and needs to be replaced in time;
below the level - check, top up, when the fifth speed is turned on, a whistle occurs, and this will soon affect the remaining gears;
the oil does not meet the recommended viscosity - it can be caused by moisture, check the color of the oil with a dipstick, there may be pale spots on it - the oil needs to be replaced.

If the gearbox is noisy when driving:

acceleration of movement when increasing the gas supply from speeds 1 to 5, can also occur when the speed is reduced - this is caused by a malfunction of the main pair and it must be replaced;
when turning on 3, 4, 5 speeds, a metal grinding noise occurs - a malfunction of the upper bearing of the secondary shaft;
the first speed is switched on, the grinding noise of metal increases, the box jams - the lower bearing of the secondary shaft is faulty;
minor weak sounds are acceptable - the gears are grinding in after assembling the box.

Advice: it is advisable to have the gearbox diagnosed at a service station.

If the oil level is low, you need to check for leaks.
Also blow out the breather.
Add oil to the level on the dipstick between the maximum and minimum marks.

When an aqueous composition gets into the oil, whitish stains appear on the dipstick.

Drain the gearbox oil:

Carry out work on a warm engine, from the inspection hole.
Prepare a five-liter container in advance.
Unscrew the oil drain plug and place the prepared container.
Wait until all the oil has drained.
After this, wipe the drain area with a rag.
Screw the plug into place.
Fill with fresh oil according to the manufacturer's recommendations.

Tip: install a splash guard on the engine. Install a rubber hose on the gearbox breather - bring it up, out of the reach of moisture.

Transmission repair

If after completing all the work the noise in the box continues to remain, then it is necessary to remove the box and disassemble it. This must be done to eliminate the causes of the metallic sound.
On the VAZ 2110, the gearbox of a mechanical design has five forward speeds and one reverse. From speeds 1 to 5, synchronizers are installed on the shafts for smooth shifting.
The entire structure is connected to the differential and final drive. The body composition is assembled from three parts of the crankcase - they are cast from duralumin metal.
Also from:

clutch;
gearboxes;
separately by the rear gearbox cover.

The parts are assembled using a gasoline-oil-resistant hermetic composition. A magnet is installed at the bottom of the crankcase, which collects metal shavings into sediment.
When draining warm oil, this sediment leaves with the drained product.

Dismantling the gearbox

To remove the box, you need to prepare tools and auxiliary materials:

socket wrench No. 10, No. 13, No. 17;
heads No. 13, No. 17;
two mounts;
plumber's hammer;
knob;
five-liter container;
rags;
metal brush;
acetic acid;
cotton gloves

Note: Before starting work, you must remove the negative terminal from the battery.

All dismantling work is carried out in an inspection pit.
Work schedule for removing the gearbox:

remove the engine splash guard;
the jet rod and drive rod are disconnected;
drain the gearbox oil;
unscrew the three bolts with 10mm heads from the bottom cover of the clutch housing;
remove it;
remove the right wheel drive;
Insert a piece of rubber hose or a wooden plug into the resulting hole - this must be done to prevent debris from entering;
unscrew the nut from the wheel bearing;
remove the ball joint;
the steering knuckle with the stand is moved to the side, the drive is removed from the hub (it should be installed in a stretcher).
Using a pry bar, carefully remove the inner joint housing from the gearbox.

Note: when removing the housing, try not to damage the protective ring that is located on it.

Remove the left drive.
Disconnect.
Remove the power supply connectors from the reversing light switch.
Disconnect the speed sensor.
Unscrew the eyelet fastening; it is secured with a 17 nut.
Remove it.
Place a spacer stand under the engine.
Remove the left engine mount.
Disconnect another rear support from the box.
Lower the spacer post.
Unscrew the three bolts and nut that secure the clutch housing.
Remove the box thus freed.
Remove the box from under the car.
Rinse it and prevent water from getting inside the device.
Clean thoroughly from dirt and oil deposits.
Use a wire brush to go over the joints and carefully clean the bolted joints.

It is advisable to entrust the repair of the gearbox to specialists from a car service center, since it is a complex structure. Experienced, qualified specialists will carry out high-quality repairs.
Replace the necessary parts. The operation of the unit will be checked at a special stand.
Upon completion of work, specialized workshops always issue a guarantee.
Install the box in the reverse order:

Fill in the oil recommended by the manufacturer for use in the transmission of this particular model.
After installation, it is necessary to adjust the clutch pedal travel.
Check that the speeds are turned on.
Adjust the gear lever by selecting the operating parameters of the rocker.
Check the operation of the box while driving.

Advice: it is necessary to promptly check the oil level in all operating units of the vehicle.

Identify the causes of gearbox noise on a VAZ-2110 after watching the video and studying photographic materials. Please read the attached instructions.
They indicate places that will help the car enthusiast to promptly identify all the subtleties when operating the car. The car is a structure made up of many systems and assemblies.
Therefore, it is necessary to gradually study the attached materials. This will greatly help the car enthusiast when operating the car and the gearbox, the gears of which should shift smoothly and comfortably.
After reading the above material, motorists are unlikely to have a question - what is this? The instructions will also help you determine the causes of the noise and repair everything in a timely manner.
The price for work on replacing and repairing a gearbox is not that low, so you can try to do everything yourself.

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