When buying a car, many drivers give preference, considering it more reliable. A manual gearbox has several advantages, the main one of which is its unpretentiousness. If we compare mechanics with or, then in the event of damage or failure of any manual transmission elements, repairs will cost the driver relatively inexpensively.
With proper operation and timely maintenance, a manual transmission will not require special attention. However, in practice, problems may arise over time in the operation of a manual transmission, as in other components of the car. One of the common problems with manual transmissions is the crunching noise that occurs when shifting the gear lever. In this case, the driver needs to determine the cause and fix the problem.
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Gearbox crunches: signs
While driving or braking the car when shifting the gearbox, the driver may hear extraneous sounds, such as crunching, grinding or crackling.
Moreover, most often, extraneous sounds when turning on the gear lever may appear only in one of the gears, for example, only when switching to first or only when switching to second, etc. Also, when returning the gear lever to the neutral position, an unpleasant cracking or grinding.
Crunching sound when engaging first gear. Before the car starts moving, when shifting into first gear, a cracking or grinding sound appears, as if the clutch pedal is not fully depressed. But when switching from second to first, the crackling noise disappears. A crunching noise may occur when shifting into first gear from second, that is, while reducing speed, for example, when braking a car in front of a traffic light.
- Crunching noise when shifting into second gear. Shifting into first gear is smooth and quiet, but there is a rattling sound when shifting from first to second gear. This happens when the car accelerates, when the engine speed increases. Moreover, all other gears shift without a crunch at any speed.
- Switching from third to second gear may also be accompanied by a crunching sound, and shifting gears can be difficult. One way or another, the problem may be a failed transmission, since the element is subject to heavy loads.
It is important to understand that if shifting the gearbox lever to higher or lower speed is accompanied by an incomprehensible crackling or grinding noise, the cause should be determined and eliminated as soon as possible.
Crunching noise when shifting gears: causes and methods of eliminating them
The causes of a crunching, crackling or grinding noise when the gearshift lever is engaged may be different. It all depends on the specific case.
In the event of a minor breakdown, without interfering with the box mechanism itself, the problem can be eliminated by replacing the damaged part. In another case, more serious, the problem is solved by overhauling the manual transmission itself.
The main breakdowns that cause crunching or crackling when changing gears:
- Failure of synchronizers. Synchronizers are responsible for smooth gear shifting. Over time, they wear out and cease to perform their functions. This leads to a crunching or crackling sound when changing gears. The problem is solved by replacing damaged synchronizers with new ones.
Failure of the clutch basket. The basket consists of “petals” that begin to fall out over time. This problem most often affects cars with high mileage. In this case, when one or more gears are engaged, extraneous sounds, such as crunching or crackling, will appear. The problem is solved by replacing the clutch basket.
- Cable malfunction. One of the most important elements of the car is the clutch cable, through which it is possible to achieve smooth operation of the clutch itself. Wearing of the clutch cable leads to its breakage, as a result of which the clutch pedal falls and a crunching or crackling sound appears when shifting gears. The problem is solved by replacing the clutch cable.
- Gearbox shaft malfunction. Another reason for unpleasant sounds when shifting gears is a malfunction of the gearbox shaft. The problem can be solved by replacing this manual transmission unit.
- Bearing wear. If there is a crunching sound in the manual transmission when changing gears or gear shifting is difficult, most likely the problem is in the gearbox input shaft bearings. The problem is solved by replacing worn parts with new ones.
How to avoid crunching noises in the gearbox
Incorrect operation and untimely maintenance of the manual transmission leads to problems in the operation of this unit. What you need to pay attention to first:
What's the result?
The appearance of a crunching sound in a manual transmission may be the first signal of a serious breakdown of this unit. Therefore, if symptoms such as crunching, grinding or crackling appear when switching the gearbox lever from high to low speed or vice versa, it is necessary to conduct a full diagnosis and identify the cause of the malfunction.
Timely elimination of the problem will help the car owner avoid more expensive manual transmission repairs, since driving with a faulty gearbox that crunches when shifting can lead to more serious malfunctions, and after a relatively short period of time.
Read also
Correct gear shifting in a car with a manual transmission: when to engage a particular gear on a manual transmission, working with the clutch pedal, errors.
As you know, a manual transmission is highly reliable and unpretentious. With proper use and timely maintenance, the “mechanics” do not often fool the driver. However, over time, this transmission may also develop malfunctions. One of the most common problems is a squeaking sound when shifting gears. What causes it and how to fix the problem will be discussed in this article.
Most often, an unpleasant crunching or grinding noise appears when switching to only one gear (for example, to second) and when switching the lever to the neutral position. If you hear a crackling, grinding or crunching sound when upshifting or downshifting, it is important to find the cause of the problem and fix it as soon as possible.
The main causes of gearbox squealing:
- Synchronizers. They are responsible for smooth gear shifting. If this element wears out, an unpleasant sound appears. To solve the problem, just install new synchronizers.
- Clutch basket. Over time, when the car has a long mileage, the “petals” of the basket begin to fall out, which also causes a crunching or crackling sound when engaging certain gears. The solution to the problem is to replace the clutch basket.
- Clutch cable. This element is responsible for the smooth operation of the clutch itself. Wear of the cable leads to its breakage, which results in the clutch pedal sinking and a crunching sound when shifting gears. The solution to the problem is to replace the clutch cable.
- Gearbox shaft. Crunching and grinding noises when changing gears can also be caused by a faulty gearbox shaft. To solve the problem, you need to replace this transmission part.
- Bearings. If, in addition to unpleasant sounds, you notice difficulty shifting gears, then there is a high probability that the input shaft bearings are faulty. As in previous cases, the situation can be corrected by replacing worn parts.
- Lack of oil. If the transmission mechanisms do not receive enough oil, this can cause a number of problems, including crunching and crackling noises when shifting gears.
How to prevent crunching noise in the gearbox? You need to understand that untimely maintenance and improper operation of the transmission lead to problems in its operation. So, it is extremely important to change the oil in the gearbox on time, because it depends on whether the shafts, gears and other elements of the manual transmission receive the lubrication necessary for their operation. Manufacturers recommend changing the oil every 60 thousand kilometers.
If a crunch does appear, you must definitely find and eliminate its cause, because Using a car with a faulty gearbox can very quickly lead to more serious malfunctions, and then simply replacing the part will no longer be enough. And a serious manual transmission repair costs quite a bit.
Are the synchronizers flying or why does the gearbox crunch when changing gear? This article will be most relevant for mechanics, since the machine gun and its types (,) have a slightly different system. A similar surprise comes from older cars that, for certain reasons, develop defects. Read below about how to identify, eliminate, and prevent.
Breakdowns that cause crunching
Does the gearbox crunch when changing gear? There may be only five reasons, but whatever it is, “surgical” intervention in the transmission is required. A slight scare will not do here, so fix it yourself or, if you have no experience, take it to a car service center.- Synchronizer: the reason is precisely its wear and tear due to the lack of an adequate level of lubrication or its old age. In such cases, any lubricant will turn from a useful substance into a harmful environment that destroys everything. It is advisable to eliminate the cause at a certified service station, since the slightest mistake can lead to failure of the entire unit;
- "Basket": Structurally, it consists of “petals,” as people call it, so after a certain mileage, which is different for everyone, they begin to loosen and fall out. As a result, the driver cannot “push up” the speed. There is only one piece of advice: completely replace the basket, and at the same time carry out a visual diagnosis of the synchronizers. Replace if necessary;
- Clutch cable: typical for most domestically produced cars. In such cases, you will not be able to turn on anything at all. You can get to the service station only by turning on the gear, and then start the car with the battery while you are moving and then continue only at this speed. The repair will take you no more than 10 minutes, just replace the cable with a new one;
- Box shaft: friction from rotation can cause a critical increase in temperature and, as a result, one or another unit will burst. There is only one way out: disassembling and replacing the contents. The main thing is that the shaft does not jam while moving, as the consequences can be much more serious;
- Manufacturing defects: anything can happen. It is necessary to completely replace the unit that has failed.
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As practice shows, most breakdowns are due to untimely replacement of the lubricant. For some reason, some drivers have the opinion that automatic ones need to be changed, but not manual ones. So it turns out that the lubricant loses its properties, which leads to breakdowns.
Most manufacturers recommend carry out replacement at 45-50 thousand km. mileage This number is the golden mean. Tightening is not recommended. Of course, depending on operating conditions, the figure can be changed (but only downward). If climatic conditions are characterized by critical temperatures towards minus or plus.
I would like to note that if the car is front-wheel drive, then a low oil level or worn-out oil is even worse for it than for a rear-wheel drive one. The whole reason is that the latter works autonomously, but the front drive is in tandem with the front axle, which also needs to be rotated and lubricated. Therefore, car owners need to pay increased attention to this.
The main thing to remember is that timely and comprehensive replacement of spare parts and lubricants can protect your car from sudden breakdowns. This concludes the topic of what to do if the gearbox crunches when changing gear. We recommend that you familiarize yourself with our recommendations for drivers, regardless of experience and length of service. Apply our tips in everyday life when repairing your car.
Unfortunately, new cars also have problems with the gearbox, namely a crunching noise when changing gears.
How does the crunch appear when switching?
The first is sound. The grinding of gears on gears cannot be confused with anything else. A clear metallic crunch, reminiscent of a growl. The second is the return to the lever. This does not always happen, but it does happen: when you try to switch, the lever, in time with the crunch, begins to vibrate finely - it seems to be thrown back.
Why the box doesn’t work like everyone else’s - it’s quiet
What's wrong?
For others, the speeds turn on without sound, but for you with a crunch? This may be a manufacturing defect in the assembly. It is no secret how cars are assembled on the assembly line and how they are tested. The problem may be the following: a low-quality ferido (clutch disc) is installed. If it is too thick, the clutch does not cool down completely. To put it simply, it turns out that you are trying to turn on the speed as if you were pressing the clutch pedal halfway.
And another reason is assembly. The box is assembled from several parts (outer casing), which are made together, that is, they are not interchangeable. If parts of the case are mixed up, a crunching noise may occur when turned on from the factory.
How to understand the cause of the crunching
Many people try to independently determine the cause of the crunching noise when switching. This is problematic, but some advice can be given.
A. If the crunch is pronounced when switching to a higher gear, for example, from first to second, then the reasons may be the following: wear of the bearings in the box, a common lack of oil, wear of the teeth (extremely rare), wear of the synchronizers (even less often), wear of the shift forks (inside the box), and a violation of the adjustment of the gear shift linkage, or the shift mechanism itself.
B. If the crunch is pronounced when switching to a lower gear, for example, from third to second, then: lack of oil (unlikely, but possible), wear of the forks, bearings, violation of the rocker adjustment. But most often, a roar when switching to a lower gear indicates wear of the synchronizers, which do not equalize the speed of rotation of the gearbox gears.
D. A growl when engaging reverse gear is a common occurrence. Due to the peculiarities of turning on the rear (no synchronization), it may growl a little when turned on. The remaining breakdowns are similar to the previous points.
And now it’s important - all of the listed symptoms may be present with clutch problems. What can happen: the release bearing is jammed. On a new car, a roar when turning on the speed may indicate a low-quality ferido disc (too thick). And of course – problems with the clutch cable. Perhaps the cable is not tensioned enough and the clutch is not pressing enough. Or - the cable becomes unusable and gradually stretches.
All you can do is check the oil level in the box and try to tighten the clutch cable (you can’t pull it indefinitely - the clutch pedal must have free play). Everything else can only be done at a service station.
Can changing the oil and other tricks help avoid repairs?
I have heard this statement more than once. From a mechanical point of view, this is not serious. Adding oil may help, but changing it is unlikely. If the box howls slightly and the roar is very insignificant, try changing the oil. The best option is to visit a specialist. The slightest breakdown in the box, which is not repaired in time, can result in serious and expensive repairs.
If we compare different types of transmissions, oddly enough, the most problem-free is the “mechanics”; the manual transmission outperforms the classic “automatic” and many of its varieties in terms of resource. However, as we know, nothing lasts forever, and “mechanics” during operation present surprises, the most common of them. The appearance of a crunch when changing gears. Of course, this unpleasant phenomenon does not cause the car to become completely immobilized, it is only the first sign of a possible serious breakdown, it indicates that problems have already arisen in the manual transmission and we need to start solving them as quickly as possible.
Causes of crunching
A manual transmission, although a rather complex unit, is nevertheless more conservative compared to an automatic transmission; it has much fewer sensors than an automatic one, and accordingly the control system is less complex. Therefore, breakdowns are most often of a mechanical nature, that is, associated with wear and tear of individual parts and elements.
So, why does the crunch occur?
1. failure of the synchronizer.
This device, by equalizing the rotation speed of gears during gear shifts, ensures a smooth transition from one speed to another. Before the use of synchronizers in manual transmissions, drivers were forced to change the throttle, which added complexity to driving; modern drivers do not have to perform such a mandatory action, they are helped by the synchronizer, but only while it is working. With severe wear, the part is no longer able to synchronize the speed of rotation of the shafts. Therefore, when the gears engage, a crunching sound appears. If this phenomenon occurs when only one of the gears is engaged, then the synchronizer is most likely to blame, which needs to be changed. It must be said that the problem with such a breakdown often arises among owners of front-wheel drive VAZs; the thing is that the engineers of the Volga plant, when designing a manual transmission for a whole family of cars, made a gross mistake, namely, they unsuccessfully selected the gear ratio of the second gear. As a result, when switching speed to second, the transmission elements experience increased loads, primarily the synchronizer.
2. Shaft wear.
Such a phenomenon as a crunching sound in the transmission can occur when the primary and secondary transmission shafts wear out. When teeth on gears wear out or bearings fail, alignment may be disrupted. If there are problems with the primary and secondary shafts, a crunch will occur when you engage not one, but several gears at once; it can also be heard while the car is moving in any gear.
By the way, the problem with wear of the shafts can also be determined by the temperature effect, if the gears are switched on smoothly when cold, without crunching, and after the oil in the box has warmed up, it appears, the reason most likely lies precisely in them.
3. Lack of oil in the box.
The reason, which in practice is not so rare, oil leakage can occur due to depressurization of the gearbox, if for some reason it has received mechanical damage, wear of the oil seals, or spontaneous failure or unscrewing of the oil drain plug. For example, on many Renault models, the gearbox and the inner CV joint of the left drive are connected to each other; oil can also leak through the CV joint. Owners of cars of this brand should take this circumstance into account. Repairing a manual transmission on such a car is much more difficult than, for example, replacing the hood on a Renault Logan ().
4. Clutch basket malfunction.
During long-term use, the petals of the basket wear out. They may even break off; in such cases, the clutch will not disengage completely, which will create a problem when shifting gears, although the gearbox will not be to blame here.
5. Problems with the clutch drive.
Much depends on what type of drive is used in the car (cable or hydraulic), there can be many reasons for the malfunction and the appearance of a crunching sound, for example, a broken cable, leakage or clogging of hydraulic fluid. Just like with the clutch basket, the gearbox is not directly to blame here, but if the clutch does not disengage completely, smooth gear shifting will also be impossible.
Typically, clutch problems affect not one, but all manual transmission gears. By this sign, you can determine that the source of the problems lies precisely in this node.
It should be noted that a crunching sound when engaging a gear is not always a sign of a breakdown; on some budget cars, for example, on the same Renault Logan 2 (there is no synchronizer in reverse gear. Therefore, if you engage reverse gear too sharply, even before a complete stop, you will hear crunch This characteristic feature cannot be eliminated, but the driver can adapt to it: do not engage reverse until it comes to a complete stop, do not do it too sharply.
Repairing a manual transmission or clutch is a costly and difficult task, but the cause of a crunching sound during gear shifting is not so difficult to determine. You need to start identifying the cause with the simplest thing, first check the oil level in the box. It is important to make sure that the rubbing parts are properly lubricated. If the oil level is okay, you will have to remove the gearbox and check the clutch. If the problem was not identified during the initial inspection, you will have to troubleshoot the unit with further replacement of worn and damaged elements, since they can be purchased separately without purchasing a complete gearbox or clutch.
Often the drivers themselves, especially inexperienced ones, provoke early wear of the manual transmission through their inept actions.
How to extend the life of a manual transmission and clutch:
1. Change the oil in a timely manner. Almost all operating instructions for modern cars with a manual transmission state that the oil poured into the transmission is filled with the expectation of the entire service life of the car. Therefore, some car enthusiasts are of the opinion that changing the oil after a certain mileage is only relevant for automatic transmissions; it is not required for mechanics. In fact, this is not entirely correct. Although a manual transmission is less critical to the purity of the transmission oil than an automatic transmission, wear products that inevitably appear over time inside the transmission reduce its service life, so it is still necessary to change the oil. How often should this be done? Opinions vary, but the most authoritative recommendations agree on mileage figures of 80-100 thousand.
2. Select the right gears. Shifting abruptly from too high to too low revs is detrimental to any gearbox, including manual ones.
3. Do not hold the clutch for a long time. Long squeezing creates additional load on individual clutch elements, reducing the life of the entire assembly; release the pedal smoothly without delay, this will save you from serious damage.
A crunching sound when shifting gears is an unpleasant, irritating phenomenon, it can be a harbinger of a serious malfunction and expensive repairs. If a problem arises, try to pay attention to it in time, and best of all, do not let it happen by following the above simple recommendations.
