He invited me, as his representative, to attend technical training from Sachs. By this point, I had been changing clutches several times with my own hands for more than ten years. But he was guided only by his own understanding of the knot and practical experience. However, it’s never too late or harmful to learn :-) It turned out that I know almost everything necessary, with the exception of a couple of nuances. I wanted to put everything I saw and heard in writing. What if you find it interesting too? And even better - if it comes in handy in practice.
Clutch
The first seminar on clutches and shock absorbers was conducted by a representative Sachs—Wolf-Peter Moritz
His classes were structured as follows: all the invitees (about 20 people) were gathered on the territory of the service center of one of the representatives. The “guinea pig” was a BMW 520, the owner of which complained of jerking after heating when releasing the pedal.
The teacher showed how to diagnose the clutch and drive itself. I asked you to pay attention to some details and remember the sensations. 
After which everyone went into the classroom and began studying the theory, and the mechanics began removing the gearbox. Then they called all the seminar participants, and the teacher showed what one should also pay attention to when doing this work, showed correct installation kit, and continued theoretical course. Then we all tried the clutch pedal on the repaired car. Then again the theory, and answers to questions. I will try to reconstruct the events in written form. I will not go deep into the structure and principle of the clutch itself; I will focus only on those details that, in my opinion, deserve it. Sorry if it didn't turn out very well.
A little theory
The most important thing to learn: CLUTCH, this is obviously weak node in the car. Its breakdown is deliberately programmed. Another question is how long it will last. The main task of the CLUTCH is to transmit torque from the engine further along the chain. This means that it must withstand a force equal to the Maximum Torque + a very small margin, about 1.1-1.3. And if the load exceeds it, the clutch will fail, thereby keeping more than expensive engine, transmission, etc.
The next thing you also need to know: the CLUTCH will work for a long time and correctly if all the elements associated with it are in good order. Therefore, when diagnosing, repairing or changing the clutch, you need to carefully understand the reasons that led to the need for intervention.
Device
The assembly itself, which we call the clutch, consists of a “basket”, a disk and a release bearing. It is in this form that they are sold as a “set”. (By the way, the manufacturer recommends giving a warranty only if the unit is replaced as a kit.)
Effort from crankshaft is transmitted by a disc with friction linings when, when the clutch pedal is released, a powerful spring plate fixed in the basket presses the disc against the flywheel. The disk itself is located on the splined part of the gearbox input shaft. Between the splined flange and the friction linings located around the perimeter there is a damper device, or “damper” torsional vibrations", which are present throughout the movement. The smoothness of starting and engagement of the clutch is helped by the springs BETWEEN the friction linings (this moment, to be honest, was a discovery for me).
Practice
Diagnostics
With the engine off, slowly press the clutch pedal. Pay attention to the smoothness of the ride. Jerks, dips, all sorts of squeaks and other sounds are unacceptable. They talk about a malfunction of the release system.
Remember the force applied when pressing the pedal. Let go slowly. The force required to hold it should not be less than that required to press it. And also without jerking.
In the version of arranging baskets for passenger cars(and there is also one for trucks) the force applied for squeezing should increase as wear occurs. This means that a “stiff” pedal in itself is already an alarming symptom.
Start the engine. Depress the clutch, count to three, shift into gear reverse. One click is allowed. If you hear a crackling sound or it is difficult to engage the gear, most likely the disk cannot move freely along the splined part of the input shaft, or there is excessive total play in the release system.
Turn the steering wheel to extreme position, park the car hand brake. Engage first gear. Smoothly release the clutch pedal. The car should try to move off in the first third of the pedal stroke. Otherwise, the squeezing system is again faulty. Hydraulic drive or cable.
After diagnostics, we proceed to removing the gearbox. If the reason for dismantling is jerking or vibration, pay attention to the remaining components of the transmission. Any part of a car has its own vibrations during operation. When the oscillation frequency of several elements coincides, vibration appears, noticeable to the driver and the car, and extraneous noise.
Clutch disc
Most common cause premature exit Clutch failure is caused by oil or grease entering, even in small quantities. At the same time, friction linings characteristic stripes of different colors remain.
Leakage points may be gearbox seals and oil seals, rear oil seal crankshaft.
Even excess lubricant added during installation. And even greasy fingerprints left during installation will certainly make their contribution.
Destruction of the damper, expressed by loss of springs, cracks in the body,
is a consequence:
Uneven wear of the linings. There are two options. If the lining facing the flywheel is thinner, the disc wedges on the splines. If the other party is the driver’s fault - incorrect operation pedal.
Basket
Not all defects may be visible when external inspection(see Photo 9). Therefore, the cart always changes automatically. If the clutch is dismantled, while carrying out other work, pay attention to the surface of the pressure plate. There should be no scratches or grooves on it
9. Not everything is noticeable to the superficial eye.
Flywheel
Be sure to check the plane.
If there are unevenness or other damage, grinding is allowed, but not more than 1 mm. In order not to reduce the clutch life, it is recommended to grind and seat under the basket. If the cause of the breakdown was oil ingress, the surface of the flywheel must be degreased with dry (!) paper, or, in extreme cases, sandpaper. The use of gasoline or any chemicals is not allowed.
If the car has driven a considerable distance with a slipping clutch, or there are other signs of overheating, you should definitely examine the surface of the flywheel for microcracks. How to determine if there was overheating? It turns out that you can by the color of the flywheel surface.
- YELLOW color corresponds to 380-420 degrees
- BLUE color corresponds to 500 degrees
- PURPLE color corresponds to 600 degrees
Release bearing.
The place of its contact with the basket is the petals. These two surfaces must match each other.
There are two types:
1. The flat working part of the bearing should work along the rounded ends of the diaphragm spring petals.
2. Conversely, if the petals are flat, the bearing should be convex.
example of differences work surface
Therefore, pay attention to whether you allowed previous owner errors, saving on bearing replacement when replacing the basket, and whether they match each other.
Release bearing guide sleeve
This part must be a perfect cylindrical shape. Remember that small scuffs, which the bearing will pass quietly in your hands, will become a serious obstacle when the real load appears
bullies, uneven wear- reason for replacement
Sometimes it happens
Clutch release mechanism
The next “thin” place is the release fork stop in the bearing. Wear should be even. And have a clearly convex shape.
This is one of the types of forks that have separate “legs”. It is important that the wear on both be uniform, or better yet, absent altogether.
The fork itself, its fasteners, axle bushings (if any) and the “fulcrum” must be carefully inspected.
Backlash, uneven wear leading to misalignment are unacceptable
There was wear on this axis, and as a result, the fork was skewed.
In cases where release fork monolithic, it is necessary to inspect loaded areas
mounting points and stops
If the drive is hydraulic, attention must be paid to the working cylinder. Taking it in your hands, slowly press on the rod and push it in completely. The stroke of the rod must be uniform, the released rod must return completely back to the stop. Otherwise, a bulkhead or replacement is necessary. Most often, the cause of unevenness is old brake fluid, partially crystallizing on the walls of the cylinder.
When replacing a faulty clutch, it is advisable to immediately change the release cable. The fact is that the cable itself moves in a plastic jacket, which, in turn, is in a metal sheath. When the pressing force for squeezing increases, the cable itself begins to saw through the plastic, and eventually inevitably begins to come into contact with the metal, as a result of which it breaks.
We must not forget the “starting point” - the clutch pedal itself. More precisely, its axis. Even with normal wear and tear clutch, the force applied to the pedal increases, which cannot but affect the bushings. Moreover, if the driver does not pay attention to the change in force, you can pay with a broken pedal unit. Second Golfs are especially susceptible to this.
And so the old clutch was removed, and the reasons were figured out. We are starting to put it back together.
- visually compare the parts of the old and new kit. Design and small details may vary, but geometric dimensions, for example diameter, must match.
- check the disk for runout
- If there is no special device for measuring clutch disc runout, put it on input shaft, and use a micrometer to check by rotating the shaft by hand. The permissible play is 0.5-0.6 mm, otherwise there will be difficulties with shifting gears.
- lubricate the splined part of the gearbox input shaft with the lubricant supplied with the kit
- put the disc on the gearbox input shaft, move it back and forth, remove the disc.
- Completely remove any grease from the input shaft, as well as any grease on the disk that has protruded beyond the edges of the splines.
- clean the guide bushing. Lubricate only if the release bearing mating part is NOT plastic. Apply a thin layer to the fork stop and those places that directly press on the bearing, having previously given them (if necessary) a spherical shape.
- clean the connecting points of the gearbox and the block. Make sure that all guides are in place and are not deformed.
- Degrease the working surface of the flywheel. Sand if necessary. Delete (for example, compressed air) friction material remains from all corners and crevices.
degrease the working surface of the clutch basket
- in the case when the basket is installed on the flywheel in a single position (due to the a-symmetrical arrangement of the guides), it is advisable to first find this position by attaching the basket to the flywheel without a disk
- determine how to install the disk correctly. Usually there is an inscription on it identifying the side facing the gearbox
- Using a jig (mandrel), install and center the clutch disc.
- Place basket. Tighten the fastening bolts by hand, starting (!) from the bottom, then the top, then crosswise. Tightening is done in three steps. First, with the effort of the hand,
- then tighten it with a wrench, and the last stage using a torque wrench.
- The use of pneumatic tools is not allowed.
- Make sure all petals of the basket are in the same plane
- where there is, install a new or cleaned plug
- attach to the gearbox block, tighten the fastening bolts evenly, mount the clutch release drive.
classic clutch
reverse clutch
A few more tips
- When working with the clutch, use only special lubricant, without graphite, which corrodes everything extremely aggressively plastic parts. Bushings, guides, etc.
- New baskets have a pressure disc with a cone. This was done on purpose to speed up break-in. So don't be alarmed if you haven't recently installed disk you will only see a small strip of the working surface (see Photo 15)
- Driving with your foot constantly resting on the clutch pedal significantly reduces the service life and reliability of the entire assembly. For example: the foot force in a winter boot for a middle-aged person, weight and height, is about 2kg, which, thanks to the system of levers at the point of contact between the bearing and the basket, turns into: 160 kg! And the force that must be applied to the spring for full compression is approximately 400 kg. Then consider for yourself
- For the first 1000-2000 km, it is strictly forbidden to significantly increase engine speed (press the gas) until the clutch pedal is completely released.
- Let me remind you once again that to lubricate all parts and components related to the operation of the clutch, starting from the pedal, you must use a special lubricant, without graphite and copper impurities.
© 2003 Yakov Finogenov
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today, at the end of 2014, I can add the following:
-over the past years, clutch practices from Sachs continue to hold the lead in price/quality/resource ratio. If you buy from trusted suppliers (which I personally don’t include Exist at all, by the way), then the likelihood of defects is extremely low.
Restored packages have not been found for a long time. The cases of marriage can be counted on the fingers of one hand. If you follow the installation technique and eliminate all faults that indirectly affect the life of the clutch, we can safely say: once you install a Sachs clutch package, you are unlikely to return to this issue a second time :-)
A clutch is one of the components of a car’s transmission, which serves to temporarily disconnect the gearbox from the engine, as well as smoothly engage it. It is a basket in which the main parts are assembled - the driven and pressure plate, fork, release bearing and leaf spring. At correct operation You only need to change the driven disk and lubricate some elements. Their list also includes a release bearing. It needs lubrication periodically, and this can be determined by the noise when you press the clutch pedal.
The release bearing is mounted on the input shaft of the gearbox and has splines on the inside that prevent it from turning. The essence of the work is this: the driver uses the pedal to create pressure in the main cylinder, which transmits it to the working piston. A rod is attached to it, and a fork is attached to the rod. It rests on special places in the release bearing (antennae), thereby pushing it along the input shaft to the leaf spring. Having rested against it, it begins to work, that is, to spin. Simply put, the device is active only when the clutch pedal is depressed, when it comes into contact with the spring.
Release bearing operation
If the car is operated in unfavorable conditions, that is, in sand, mud, water, etc., then there is a risk that the release bearing will begin to make noise. Water is especially dangerous, as it easily gets into all the gaps and holes. The bearing itself is closed, but there is nothing sealed around it, so all the moisture and dust gets there. Then the question arises, is it possible to somehow restore it?
In principle this is possible, but not in all cases. If it gets too worn out you will have to throw it away. Well, the essence of restoration is to clean it and re-lubricate it. In general, such things are not intended for repair. Simply put, everything sealed bearings They are filled at the factory with lubricant, which is just enough for the duration of operation. If you are going to update it, then think about whether it is worth it. But in any case it is possible.
Appearance of the release bearing
Based on the above material, we learned that the release bearing is mounted on the input shaft of the gearbox. This means that when replacing it you will have to remove it too. And then the question immediately arises: “Is it possible to lubricate the release lever without dismantling the boxes?”
Release bearing in gearbox
Unfortunately, it is impossible to do this when it is installed on the car. Moreover, you won’t even be able to get close to it, since the so-called clutch cover or bell will get in the way. Therefore, in order to lubricate the release lever, you must first remove the box and not invent a bicycle. Then the question arises again. Why lubricate it at all if you have to disassemble half the transmission to do it? It’s easier to just buy a new one, install it and not fool yourself. This is basically what most drivers do, moreover, it is highly recommended to do so! But, if you need this fundamentally or for some other reason, you can remove the old release lever and lubricate it.
Before lubricating the release lever, you still need to get to it. As you understand, it is far from being in the very accessible place, so you have to confuse your head to remove it. But before that, make sure whether this is necessary. If you don’t hear any extraneous noise when you depress the clutch pedal, then there’s no point in going there. Well, if the problem is serious, then you still need to check. To do this, we prepare the tool and begin the disassembly process.
You need to remove all components carefully and carefully so as not to damage yourself or break others. important mechanisms. It's better to collect everything in reverse order, without confusing anything.
You can watch the video for more information about removing the release bearing:
So, the question has come about what kind of lubricant should be used. Everyone has different opinions on this matter and no one comes to a common decision. It’s worth saying right away that a freshly purchased bearing does not need this procedure, since it already has its own factory portion lubricant. But, if you removed a release valve that was already working, and it is still intact, then this is a relevant topic.
By turning to the literature, you can find the main types of lubricants that were used previously. This grease and nigrol. The latter is also poured into rear axle car. So, these two substances, in principle, are suitable for a release bearing. However, over time, more advanced types of lubricants have been invented that do their job better. Can be used molybdenum or graphite lubricant . Although the latter is not necessary, since the bearing does not experience much heat.
Almost any thick grease is suitable for lubricating the release bearing. synthetic lubricant
Currently, there are many types of grease designed for a variety of purposes. Almost all of them are suitable for our situation. Take, for example, Castrol. If you suddenly get lost when shopping, you can ask the seller, who will select the right product for you. The most important thing is that it is a synthetic lubricant. Otherwise, it will not last long and will begin to coke, that is, curl into small pieces.
How to lubricate a release bearing
After you have removed the gearbox and reached the release lever, you should immediately pay attention to its condition. The ears into which the fork rests must be intact - not bent or cracked. And, of course, check the bearing itself for play. If there is one, you can throw it away without any questions and go to the store for a new one. car parts. But, if, to your surprise, there is no beating, then there is still a possibility of restoration. It is enough just to lubricate it well.
Please note that the bearing cannot be disassembled, so the lubricant will have to be pushed only into those gaps left by the metal sealing rings. This can be done different options, there are already a couple of options for this matter. Objectively, they can be divided into two main methods.
Posted in Useful articles
Signs of bearing failure are approximately the same for any vehicle component. Bearing failure is actually a fairly common problem, since these parts are subject to constant heavy loads, which means they wear out faster than most other components.
Primary shaft bearing location
In most cars, the input shaft bearing does not have to take a long time to find: it is located on the input shaft directly after the oil seal, and in some gearboxes it even combines the functions of a bearing and an oil seal. Because of this, it experiences constant loads transmitted from the engine, along with the release bearing. To produce visual inspection To make sure it is broken or serviceable, just drain the oil and remove the casing from the gearbox. As a rule, they are installed on the input shaft roller bearings, the dimensions of which may vary for different brands machines.
Symptoms of bearing failure
- When the input shaft bearing fails, a characteristic howling sound is heard. You can diagnose a breakdown using Idling engine while releasing the clutch. A whistling or howling sound can also be heard while the car is moving. If partial destruction of the bearing occurs, the howling sound is replaced by a knock.
- Sometimes a sign of bearing failure is a failure of the clutch, which either does not engage or does not disengage. This usually happens if the bearing seizes due to partial failure. The most severe accidents are accompanied by damage to the input shaft on which the bearing is mounted.
- A whistling sound in the gearbox is a sign of lack of bearing lubrication. This problem is eliminated after applying fresh lubricant.
- A howling sound most often indicates the appearance of chips or cracks in the bearing housing, possibly the destruction of one or more rollers. If the bearing is seriously damaged, a knocking noise is heard when the engine is turned on. When these sounds appear, you should not leave the engine running for a long time, since the friction of the debris causes strong heating of the metal, and the bearing is literally welded to the shaft. If it happened, it will take complete replacement both parts.
How to replace the bearing on the input shaft?
Often, descriptions of the steps for replacing a bearing indicate that this requires completely disassembling the gearbox, but in practice it is usually enough to remove the casing from the gearbox. Of course, before this you will have to:
- disconnect the battery terminals;
- remove all chips from the body;
- unscrew the speedometer drive;
- remove the “pants” of the exhaust removal system;
- remove the box from its place.
The case often turns out to be heavily contaminated with road dust - it is advisable to remove all this dirt and then remove the bell from the box.
The bearing is usually secured using a set of retaining rings, which can be removed by simply pressing a screwdriver. It is convenient to remove the rings from their place using tweezers. After this, insert the tip of a screwdriver into the annular groove of the bearing and move the input shaft forward.
During installation, the bearing is pressed onto the shaft, so to remove it you will have to use a hammer, turning the shaft in all directions to press it out. You should not rush to avoid damaging the shaft - this operation may take about 15-20 minutes. Experienced craftsmen use special tools- pullers, but in an ordinary garage a simple tool set is sufficient.
The new bearing needs to be lubricated motor oil, then put it on the shaft and just as carefully press it in, lightly hitting it with a hammer in a uniform rhythm in a circle. After pressing, make sure that the bearing is level, rotates freely, without runout. After this, you can reassemble the box by installing all the removed parts in the reverse order.
How to lubricate the input shaft bearing?
If during the inspection it turns out that the bearing is not damaged, but there is no lubricant in it, it is enough to apply a new layer of lubricant and then install it in place. Of course, if available new part It is not advisable to install the old one: even if it does not appear to be damaged, metal wear is still present, and the old bearing will not work for a long time.
You need to lubricate both the old and new bearing. You can do this in one of two ways:
- boil in lithol, placing the container in a water bath;
- inject lithol into the bearing using a syringe (this takes longer, but is safer).
After lubrication, the bearing is installed on the input shaft as described above.
A manual transmission is a unit that functions all the time while the engine is running, so its elements quite often break down. Knowing the signs of a faulty input shaft bearing, each driver will be able to promptly recognize this damage to the gearbox and promptly repair it, preventing further destruction of gearbox parts. If you do not pay attention to the alarming symptoms, a small malfunction may result in the need to replace the entire box.
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