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Clutch 20 - Repair

For the assembly of a self adjusting clutch a special adjustment is needed.

Even before one begins, one should at least be informed about the price and the availability of a complete clutch. Apart from that, all the necessary, and any special tools should be available. Without a manual or valid test- and torque values, it's not going to work. Sometimes it can be sensible to compare the total prospective expenses with an estimate from a reasonable workshop and to consider the remaining value of the vehicle. Is the repair really worthwhile?

We take it for granted that all the accident prevention regulations are adhered to. When removing the clutch, as a rule, the starter must be removed as well, it is wise therefore, to take all the necessary steps to make sure that the starter can be dismantled. Remember that when the radio is reconnected, it may be dependant on a radio-code, otherwise it won't work. Pay attention to any further problems that may arise concerning the battery, however, the main lead to the starter must be free.

Of course you have already made sure that the mistake is in fact, in the clutch itself and not possibly caused by it's operation. You may have noted that, e.g., in the higher gears the clutch is slipping despite sufficient play in the operation. You may no longer be able to change gears without grinding, even though the clutch release mechanism directly on the clutch, is moving far enough when the clutch pedal is pressed.

In order to replace the clutch, in most cases the gearbox is dismantled. Very rarely must the engine be removed at the same time, as, e.g., is the case with the Porsche 911. These sports cars, and also off-road vehicles, are possibly all-wheel-drive, which complicates the removal/re-installation even further. Even practised mechanics sometimes need a whole day for this job.

As far as rear engined old-timers are concerned, (e.g. the Beetle) it may be that only the engine is removed. Otherwise one dismantles a casing, which in a front engine and rear-wheel drive, only houses the gearbox. In a front-wheel drive it also houses the axle drive. Previously, with Opels, the gearshaft could be pulled back. The gearbox remained in place. In their successive models it is partly drawn out by way of threaded rods.

Before finally beginning, one further word of advice. At this point, we feel obliged to draw your attention to an, in most cases, necessary engine mounting, because when removing the gearbox, the engine loses at least one effective mounting support. One can make a support like this oneself, which is mostly placed across the engine compartment and which holds the engine up, e.g., through a chain or a cable.

Supporting the engine from below is unfavourable, because the vehicle height possibly varies and/or the oil-sump should nearly always be left alone. In the heat of the moment a support like this can easily be pushed to one side. Even if the falling engine doesn't cause any injuries,The still hot coolant emerging from the torn pipes may well do so.

Should an impact wrench not be available, the best thing to do is to loosen the wheel-bolts before raising the vehicle. As a rule, with a front-wheel drive, this also means the axle bolts. The wheels may also have to be removed. In my opinion, the worst bolts should be taken on first, which means the axle drive shaft mountings. Perhaps not quite as bad, is the cardan shaft with a rear-wheel drive. In some vehicles, the wishbone, or even the complete suspension strut must be dismantled.

At the beginning of the work from below, it is important that any electrical, or even mechanical (speedometer) connections be taken apart. A possible earth-strip must also be disconnected, under no circumstances should it be forgotten afterwards. Then, all the gearbox-side supports must be taken care of and sometimes also the inner mudguards. Modern cars also require the dismantling of the underbody covering. If the axle drive shafts have to be pulled out of the final drive, draining the gearbox oil may be sensible.

Sometimes the operating mechanism of the clutch can be complicated. Should it be hydraulically operated, the opening of the hydraulic system is to be avoided, the slave cylinder should be dismantled and the piping sealed. Should this not be possible, the brake-fluid reservoir should be emptied to 'min', then afterwards, (only) the clutch operation must be bled. In the case of a cable, at first sight it looks easier. It must be uncoupled. If however, it has an automatic re-adjustment device, you will have certain difficulties later. By the way, it may be necessary to dismantle the entire exhaust system from below (Fiesta).

Further work is necessary in the engine compartment. All the plug-in connections here must be disconnected and the starter must be removed. Sometimes shift linkags or shift cables are complicated (see figure 4). Try to find a place where they can be laid. Try to avoid changes in the adjustments. Apparently there are rear-wheel drives, e.g., old-timers, where the entire center console has to be removed. So far, so good.

Have we come that far that we can unbolt the gearbox? Right now actually, an assistant or one of these nice, hydraulic lifting devices would be a great help. Take a lot of care when building a platform or table for the gearbox. Remember to move this a short distance from the engine, so that it can be lowered. I hope, for your sake, that in the end , the engine is suspended in the car, and that the gearbox is securely lying on the floor.

The most we'll notice in the gearbox, is whether a lot of (black) friction-dust or oil is in the clutch-housing, which would mean the replacement of at least one oil-seal. Otherwise we can put it to one side and we can concentrate on the engine. Don't just start loosening the bolts, first have a good look. Does, e.g., the release lever show signs of grinding? Are any teeth broken in the disc-spring? You might argue that these parts will be replaced anyway, and you're right. Take note now, in which direction the clutch-plate is installed!

The screws on the pressure-plate are loosened in several steps in a cross-wise fashion. The flywheel can now be seen. The checking for grooves or areas here which are blue-tinted through overheating, is of paramount importance. Should neither be present, the flywheel can be further used. Should you however, suspect that oil in the clutch housing is from the engine side, then the seal behind it must be renewed.

No, you cannot begin with the installation of the new parts yet. Newer vehicles have a dual-mass flywheel and this should be checked. Hopefully you have the possible twist-angle, which is, in all cases, greater than 20°. Gradually, the possibility of twisting the gearbox-side flywheel part, in relation to the crankshaft, must become more and more difficult. The possible tilting-play between the two flywheel halves should also be checked.

Now, you've cleaned all the parts?, and you've already opened the carton with the pressure plate, the clutch disc and the release lever. Consider for a moment, to ensure that no mistakes are made! What is now still to be done. One example could be, a slave cylinder integrated into the clutch housing or a central release unit. This could be replaced, even if there is no leakage. Otherwise, at least, another gearbox removal would be due.

Now, in preparation for the re-installation of the construction, there is still additional work to be done, there, where the gearbox shaft is mounted into the center of the flywheel or into the crankshaft. Should your flywheel have a hole in the center, extreme care is to be taken. At this point, it is easily possible to wipe out the engine and the gearbox with one blow. So, pay attention to a slide- or even a needle bearing. Are the needles complete, intact and do they stay in the right place when the gearbox is remounted?

No, we mount the the new clutch only after we've tried out the new clutch-disc on the transmission drive shaft (see figure 5). Is it form-fitting here? Can it be axially moved without problems? One should lubricate only very sparingly here. Perhaps a little on the surface of the release lever (if available) on the release bearing. Teflon or similar lubricants e.g., should, under no circumstances be used. The new parts should only be cleaned on the thrust surfaces.

The screws around the edge of the pressure plate should be tightened, once again, crosswise and in several steps. At the latest now, it should be mentioned, that for almost all nuts and bolts used in motor vehicles, torque values exist, which must be adhered to. It is wise to now wait a moment longer, because the clutch disc must be exactly concentric, e.g., with the flywheel behind it, otherwise you can forget about mounting the gearbox. Workshops have simple devices for checking (see figure 6). Can you rely solely on your visual judgement?

We will now see whether or not the gearbox installation turns out to be the biggest botch-up of the century or not. Please, use only the force of your arms. Levering force or even extending bolts with nuts are forbidden. If you need more force, then something is wrong (see above), and the mistake must first be remedied. Whoever uses brute-force now, is taking the risk that later, the clutch does not separate cleanly, and that would take care of that!

Everything in and on? All the electrics and earth strips? The perhaps still available speedometer cable? Can all the gears be engaged? Have all the functions been checked after connecting the battery? Now we can devote ourselves to the clutch cable with automatic adjustment. Either you replace it with a new part (not cheap) or you can read on further here.

Everything tightened, also and particularly the engine mountings, wheels and drive shafts? Then we can check the starter, by starting the engine. Should there be no unusual noises, we can drive off. Should your car still have an adjustable clutch cable, the clutch should come in about two centimeters before the end position, if not, it must be adjusted. The only question now is, does pulling off, clutching and gear shifting seem as it was before the repair. 01/10

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