He invited me, as his representative, to listen to a technical training from Sachs. By this time, I have repeatedly changed clutches 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, learning is never too late and not harmful :-) It turned out that I know almost everything you need, with the exception of a couple of nuances. I wanted to put everything I saw and heard in writing. Will you be interested 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 by one of the representatives of the "Guinea pig" served as a BMW520, the owner of which complained about jerks after heating, when the pedal was released.
The teacher showed how to diagnose the clutch itself, the drive. He asked me to pay attention to some details, and remember the sensations. 
After that, everyone went to the classroom and began to study the theory, and the mechanics began to remove the CP. Then they called all the participants of the seminar, and the teacher showed what should also be paid attention to in this work, showed the correct installation of the kit, and continued the theoretical course. Then we all tried the clutch pedal on a repaired car. Then again the theory, and answers to questions. I will try to reconstruct the events in writing. I will not go deep into the device and the principle of the clutch itself, I will focus only on those details that, in my opinion, deserve it. Sorry if it's not very good quality.
A bit of theory
The most important thing to learn: CLUTCH, this is obviously weak knot in the car. Its breakdown is intentionally programmed. Another question is how long it will last. The main task of the CLUTCH is to transfer 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, of the order of 1.1-1.3. And if the load exceeds it, the clutch will fail, thereby keeping the more expensive engine, transmission, etc. in working order.
The next thing you also need to know: CLUTCH will work for a long time and correctly if all the elements associated with it are in good condition. Therefore, when diagnosing, repairing or changing the clutch, it is necessary 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 disc and a release bearing. It is in this form that they are sold as a "kit". (By the way, the manufacturer recommends giving a guarantee only if the assembly is changed as a kit.)
The force from the 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 "torsional vibration damper", which is present throughout the movement. The smoothness of starting and engaging 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 depress the clutch pedal. Pay attention to smooth running. Jerks, dips, all sorts of squeaks, etc. sounds are unacceptable. They talk about a malfunction of the release system.
Remember the force applied when you press the pedal. Let go slowly. The force to hold it must be NOT less than that required to press it. And also without jerks.
In the variant of the device baskets for cars (and there are also for trucks), the force applied to the squeeze should increase as it wears out. So in itself a “tight” pedal is already an alarming symptom.
Start motor. Squeeze the clutch, count to three, engage reverse gear. One click is allowed. If a crack is heard, or the gear is difficult to engage, 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 the extreme position, put the car on the handbrake. Engage first gear. Slowly release the clutch pedal. The car should try to start in the first third of the pedal travel. Otherwise, the release system is again faulty. Hydraulic drive or cable.
After the diagnosis, we proceed to the removal of the gearbox. If the reason for dismantling is jerks or vibrations, pay attention to the rest of the transmission components. Any part of the car in the process of work has its own fluctuations. When the oscillation frequency of several elements coincides, a vibration appears that is noticeable to the driver and the car, extraneous noise appears.
Clutch disc
The most common cause of premature clutch failure is the ingress of oil or grease, even in small quantities. At the same time, characteristic stripes of different colors remain on the friction linings.
Leakage points can be gearbox seals and oil seals, crankshaft rear oil seal.
Even excess grease applied during installation. And even greasy fingerprints left during installation will certainly contribute.
Destruction of the damper, expressed by the loss of springs, cracks in the body,
is a consequence:
Uneven pad wear. There are two options. If the lining facing the flywheel is thinner, the disc wedged on the splines. If the second side is the driver’s fault, the pedal is not working properly.
Basket
Not all defects may be visible during external examination (see Photo 9). Therefore, the basket is always automatically changed. If the clutch is dismantled, in passing, when carrying out other work, pay attention to the surface of the pressure plate. It should not have scratches, grooves
9. Not everything is visible to the surface
Flywheel
Be sure to check the flatness.
If there are irregularities 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 the seat under the basket. If the cause of the breakdown was the ingress of oil, the surface of the flywheel must be degreased with dry (!) Paper, in extreme cases - sandpaper. The use of gasoline or any chemicals is not allowed.
If the car has traveled a considerable distance on the slipping clutch, or there are other signs of overheating, it is imperative to examine the surface of the flywheel for microcracks. How to determine if there was overheating? It turns out that it is possible by the color of the surface of the flywheel.
- YELLOW color corresponds to 380-420 degrees
- BLUE 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.
There are two types:
1. The flat working part of the bearing should work on the rounded ends of the petals of the diaphragm spring.
2. Conversely, if the petals are flat, the bearing should be convex.
example of work surface differences
Therefore, pay attention to whether the previous owner made a mistake by saving on replacing the bearing when replacing the basket, and whether they match.
Release bearing guide bush
This part must be a perfect cylindrical shape. Remember that on small scuffs, which the bearing in your hands will pass quietly, will become a serious obstacle when a real load appears.
scoring, uneven wear - reason for replacement
Sometimes it happens
Clutch release mechanism
The next “thin” place is the release fork stop in the bearing. Wear must be even. And have a clearly convex shape.
this is one of the varieties of a fork that has separate "legs". It is important that the wear on both is uniform, or better, that it would be completely absent.
The fork itself, its fasteners, axle bushings (if any) and "fulcrum" must be carefully inspected.
Backlash, uneven wear, leading to misalignment are unacceptable
wear was present on this axle, and as a result, the fork was skewed.
In cases where the release fork is monolithic, it is necessary to inspect the loaded places
attachment points and stops
If the drive is hydraulic, attention must be paid to the working cylinder. Picking up, slowly press on the rod, drown it to the end. The stroke of the rod must be uniform, the released rod must fully return back, until it stops. Otherwise, a rebuild or replacement is necessary. Most often, the cause of unevenness is the old brake fluid, partially crystallizing on the walls of the cylinder.
When replacing a faulty clutch, it is advisable to change the release cable immediately. The fact is that the cable itself moves in a plastic shirt, 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 as a result, it will inevitably begin to come into contact with the metal, as a result of which it will break.
Do not forget the "starting point" - the clutch pedal itself. More precisely, its axis. Even with natural clutch wear, 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 effort, you can also pay with a broken pedal block. The second Golfs are especially susceptible to this.
And now the old clutch has been removed, the reasons have been sorted out. We start collecting back.
- visually compare the parts of the old and new kit. Design and small details may vary, but geometric dimensions, such as diameter, must match.
- check disk for runout
- if there is no special device for measuring the runout of the clutch disc, put it on the input shaft, and use a micrometer to check by rotating the shaft by hand. The allowable play is 0.5-0.6mm, otherwise, difficulties will begin with the inclusion of gears.
- lubricate the splined part of the gearbox input shaft with the grease supplied with the kit
- put the disc on the input shaft of the gearbox, move back and forth, remove the disc.
- Completely remove grease from the input shaft, as well as grease on the disc that has protruded beyond the edges of the splines.
- clean the guide bushing. Lubricate only if the release bearing mating piece is NOT plastic. Apply a thin layer to the stop of the fork, and those places that directly press on the bearing, after giving them (if necessary) a spherical shape.
- clean the docking points of the checkpoint and block. Make sure all guides are in place and not deformed.
- Degrease the working surface of the flywheel. Sand if necessary. Remove (eg with compressed air) residual friction material from all nooks and crannies.
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 asymmetric 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 correctly install the disk. It usually has an inscription identifying the side towards the gearbox.
- Using a jig (mandrel), install and center the clutch disc.
- Place a basket. Screw on the fastening bolts with your hands, starting (!) From the bottom, then the top, then crosswise. The tightening is done in three steps. First, by hand
- then hold out with a key, and the last stage using a torque wrench.
- The use of pneumatic tools is not allowed.
- Make sure all the petals of the basket are in the same plane
- where present, install a new or cleaned plug
- attach to the gearbox block, evenly tighten the mounting bolts, mount the clutch release drive.
classic clutch
reverse clutch
Some more tips
- When working with the clutch, it is necessary to use only a special lubricant, without graphite, which corrodes all plastic parts extremely aggressively. Bushings, guides, etc.
- The new baskets have a pressure plate with a cone. This was done on purpose to speed up the break-in. So don't be alarmed if you see only a small strip of working surface on a newly installed disk (see Photo 15)
- Driving with a foot constantly lying on the clutch pedal significantly reduces the resource and reliability of the entire assembly. For example: the force of a leg in a winter boot of a middle-aged person, weight and height, is about 2kg, which, thanks to the lever system 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 squeezing is approximately 400 kg. Then consider yourself
- The first 1000-2000 km is strictly forbidden to significantly increase the engine speed (press the gas) until the clutch pedal is completely released.
- Let me remind you once again that to lubricate all parts and assemblies related to the operation of the clutch, starting from the pedal, it is necessary to use a special lubricant, without impurities of graphite and copper.
© 2003 Yakov Finogenov
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today, at the end of 2014, I can add the following:
- Over the past years, Sachs clutch practices still hold the lead in terms of price / quality / resource. If you buy from trusted suppliers (to which I personally do not attribute Exist at all, by the way), then the probability of marriage is extremely small.
Restored packages have not come across for a long time. Cases of marriage can be counted on the fingers of one hand. Subject to the installation technique and the elimination of all malfunctions that indirectly affect the clutch life, we can safely say: putting the Sachs clutch package once, you are unlikely to return to this issue a second time :-)
Posted in Useful articles
Signs of bearing failure are approximately the same for any vehicle components. Bearing failure is actually a fairly common problem, as these parts are subjected to constant heavy loads, which means they wear out faster than most other components.
Location of input shaft bearing
In most cars, the input shaft bearing does not have to be looked for for a long time: 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 make a visual inspection and make sure that it is broken or in good condition, it is enough to drain the oil and remove the casing from the gearbox. As a rule, roller bearings are installed on the input shaft, the dimensions of which may differ for different brands of machines.
Bearing failure symptoms
- When the input shaft bearing breaks, a characteristic howling sound is heard. You can diagnose a breakdown at idle speed of the engine, while releasing the clutch. A whistling or howling sound can also be heard while the car is moving. If there was a partial destruction of the bearing, the howling sound is replaced by a knock.
- Sometimes a sign of a bearing failure is a clutch failure that either won't engage or disengage. This usually happens if the bearing seizes as a result of partial failure. The most severe accidents are accompanied by damage to the input shaft on which the bearing is mounted.
- Whistling in the gearbox is a sign of a lack of bearing lubrication. This problem is eliminated after applying fresh lubricant.
- The 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 knock is heard when the engine is turned on. When these sounds appear, the engine should not be left running for a long time, since the friction of the debris causes a strong heating of the metal, and the bearing is literally welded to the shaft. If this happens, a complete replacement of both parts will be required.
How to replace the bearing on the input shaft?
Often, in the descriptions of the actions for replacing the bearing, it is indicated that for this it is necessary to completely disassemble the gearbox, but in practice it is usually enough to remove the casing from the box. Of course, before that you will have to:
- disconnect the battery terminals;
- discard all chips from the case;
- 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 polluted with road dust - it is advisable to remove all this dirt, and then remove the bell from the box.
The bearing is usually secured with a set of circlips that can be removed with a simple push of a screwdriver. It is convenient to remove the rings from the place with the help of tweezers. After that, 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 work with a hammer, turning the shaft in all directions to press it out. You should not rush, so as not to damage the shaft - this operation can take about 15-20 minutes. Experienced craftsmen use special tools - pullers, but in an ordinary garage, the simplest tool kit is enough.
The new bearing must be lubricated with engine oil, then put on the shaft and just as carefully pressed in, lightly striking with a hammer in a uniform rhythm in a circle. After pressing in, make sure that the bearing is straight, rotates freely, without beating. After that, you can assemble the box by installing all the removed parts in reverse order.
How to lubricate the input shaft bearing?
If during the inspection it turned out that the bearing is not damaged, but there is no grease in it, it is enough to apply a new layer of lubricant, and then install it in place. Of course, if there is a new part, it is undesirable to install the old one: even if it is not damaged in appearance, metal wear is still present, and the old bearing will not work for a long time.
Lubricate both the old and the new bearing. You can do this in one of two ways:
- boil in lithol by placing the container in a water bath;
- inject lithol into the bearing with a syringe (this is longer, but safer).
After lubrication, the bearing is mounted on the input shaft as described above.
A manual gearbox is a unit that functions all the time while the engine is running, so its elements quite often come into a state of breakdown. Knowing the signs of a malfunction of the input shaft bearing, each driver will be able to recognize this damage to the gearbox in a timely manner and eliminate it in a timely manner, preventing further destruction of the gearbox parts. If you do not pay attention to alarming symptoms, a small malfunction may result in the need to replace the entire box.
Is there a strange noise in the Seat gearbox? Come visit us at our Transmission Repair Service. Our experts will diagnose, identify the problem and fix it at a very attractive price.
The clutch is one of the transmission units of the car, which serves to temporarily disconnect the gearbox from the engine, as well as to smoothly turn it on. It is a basket in which the main parts are assembled - a driven and pressure plate, a fork, a release bearing and a petal spring. With proper operation, you only need to change the driven disk and lubricate some elements. The list also includes the release bearing. Periodically, it needs lubrication, and this can be determined by the noise when you press the clutch pedal.
The release bearing is put on the input shaft of the gearbox and has splines on the inside that prevent it from turning. The essence of the work is as follows: the driver creates pressure in the master cylinder with a pedal, which transfers it to the working piston. A stem is attached to it, and a fork is attached to the stem. It rests against special places of the release bearing (antennae), thereby pushing it along the input shaft to the petal spring. Leaning against it, it starts to work, that is, to spin. Simply put, the device is only active when the clutch pedal is depressed, when it comes into contact with the spring.
Release bearing operation
If the car is operated in adverse conditions, that is, on sand, mud, water, etc., then there is a risk that the release bearing will start to make noise. Especially dangerous is water, which easily enters all gaps and openings. The bearing itself is closed, but around it it is not protected by anything hermetic, so all moisture and dust get there. Then the question arises, is it possible to restore it somehow?
In principle this is possible, but not in all cases. With severe wear, you still 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, all sealed bearings are packed at the factory with grease, which is just enough for the duration of operation. If you are going to update it, then consider whether it is worth it. But in any case, it's possible.
The appearance of the release bearing
Based on the above material, we learned that the release bearing is dressed on the input shaft of the gearbox. This means that when replacing it, you will have to remove it. And then the question immediately arises: “Is it possible to lubricate the clutch release without dismantling the box?”
Release bearing in gearbox
Unfortunately, it is impossible to do this when it is installed on the car. Moreover, you won’t even crawl up to it, because the so-called cover or clutch bell will interfere. Therefore, in order to lubricate the clutch release, you must first remove the box and not invent a bicycle. Then the question arises again. Why lubricate it at all, if for this you have to disassemble half the transmission? It’s easier to immediately 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 it in principle or for some other reason, you can remove the old clutch release and lubricate it.
Before lubricating the clutch release, you still need to get to it. As you understand, it is located far from the most accessible place, so you have to fool your head to remove it. But before that, make sure you need to do it. If with the clutch pedal depressed you do not hear extraneous noise, then there is nothing to climb 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 nodes carefully and carefully so as not to damage yourself and not break other important mechanisms. It is better to collect everything in the reverse order, without confusing anything.
You can see more about removing the release bearing in the video:
So, the question arose about what kind of lubricant to use. On this issue, everyone has different opinions and no one comes to a single decision. It should be said right away that a freshly purchased bearing does not need this procedure, since it already has its own factory portion of lubricant. But, if you removed an already working clutch release, and it is still intact, then this is a hot topic.
Turning to the literature, you can find the main types of lubricants that have been used previously. This solidol and nigrol. The latter is also poured into the rear axle of the car. So, these two substances, in principle, are suitable for the release bearing. However, over time, more advanced types of lubricants have come up that do a better job. Can be used molybdenum or graphite lubricants. Although the latter is not necessary, since the bearing does not experience much heat.
Almost any synthetic grease will work to lubricate the release bearing.
Currently, there are a lot of types of thick lubricants designed for a variety of purposes. Almost all of them are suitable for our situation. Take, for example, Castrol. If you still suddenly get lost when buying, you can ask the seller who will pick up the right product for you. The most important thing is that it be a synthetic lubricant. Otherwise, it will not last long and will begin to coke, that is, curl into small pieces.
How to lubricate release bearing
After you have removed the gearbox and got to the clutch release, you should immediately pay attention to its condition. The lugs against 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 question and go to an auto parts store for a new one. But, if, surprisingly, there is no beating, then there is still the possibility of recovery. It is enough just to lubricate it well.
Please note that the bearing is not disassembled, so the lubricant will have to be pushed only into those gaps that the metal sealing rings left. You can do this in different ways, there are already a couple of options for this case. Objectively, they can be divided into two main ways.
