Repair Izh Oda: Diagnosis of clutch faults

If the clutch does not disengage, the cause is not necessarily clutch related.

The cause of the malfunction is often related to the clutch release system or a stuck support bearing or failure to follow important installation instructions.

Therefore you need to check:

during installation, were all special control points specified in the instructions taken into account:

the presence of worn parts, cable, hydraulics, hinge joints;

correct installation.

Excessive clutch disc end runout

Cause:

the bending occurred during transportation or installation. Increase in lateral runout threshold +/- 0.5mm

Result:

The prescribed pressure plate pressure level is not sufficient to ensure complete disengagement of the clutch.

Note:

Always check the clutch disc for axial/lateral runout before installation.

Gazelle clutch pedal does not press

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Pedal without kinks. 500 RUR Crankshaft - there is wear, good for first repair, no carbon deposits. 1300 RUR.

Not long ago I noticed that in order to depress the clutch pedal in my car, I now need to put in twice as much effort. I found the reason.

Hello, anyone who has driven old VAZ cars understands what a tight clutch pedal is. And it was not a breakdown at all, it was like that from the factory.

But when such a problem occurs in newer cars, even a VAZ 2110, not to mention foreign cars, this is a malfunction that needs to be eliminated.

Now I will try to clearly explain why the clutch pedal becomes tight and how to repair the problem with your own hands.

I want to say right away that there are two types of clutch drive: cable-based and hydraulic. 1st is simpler, but such malfunctions most often occur with it. Below is a diagram of how a cable clutch works.

Let's figure out when and by what signs we can draw a conclusion that something is wrong.

Hub profile broken / burrs formed

Cause:

the clutch basket and the crankshaft housing flange are not centered, runout due to angular and parallel misalignment;

the support bearing is missing;

The transmission input shaft has too much clearance or is not driven.

Result:

jamming or misalignment of the hub on the input shaft of the gearbox.

Note:

also leads to the formation of noise.

Clutch not fully engaged or not engaged

Slipping usually appears when you sharply press the gas, when the speed increases, but no noticeable acceleration is observed. In this case, a characteristic burning smell may appear. If slippage is detected, which indicates that the clutch is not fully engaged, the reason should be sought in the following:

increased production (wear) or burnout of linings;

insufficient rigidity of the diaphragm spring;

swelling of the cuffs of the main cylinder (main cylinder), which leads to a slow return of the piston.

First wipe oily surfaces with gasoline or white alcohol, and then dry them thoroughly until completely dry. You should also find out the cause of the oil leak. This may be a violation of the engine or gearbox seals.

If the friction linings have become unusable, replace the HP with a new analog assembly.

Insufficient rigidity of the diaphragm spring does not provide sufficient force for hard contact, which is why slippage occurs. Simply replace the “basket” (pressure plate) with a new set along with the housing.

To restore the performance of the master cylinder, you can replace the cuffs or purchase a new spare part assembly.

The clutch does not disengage when the flywheel sticks to the disc. This sometimes happens when the car is parked for a long time. You need to break the disc by starting to move without pressing the pedal. After accelerating, depress the pedal and brake sharply.

Characteristic jerks at the beginning of movement after engaging the clutch can mainly be caused by the following circumstances:

If in developed European countries, Japan and the USA, passenger cars with a manual transmission have long been a hopelessly outdated archaism (except for some sports cars and vintage cars), in the CIS everything is exactly the opposite.

Most models (even new ones) on domestic roads are representatives of the budget segment. Such cars are traditionally equipped with the usual “mechanics” to reduce the cost as much as possible.

However, it's not just about the price. Compared to an “automatic” (automatic transmission) and even more so a “robot” (manual transmission), a traditional manual transmission is distinguished by enviable endurance, long service life, ease of maintenance and a very reasonable cost of repairing a transmission of this type.

So, there are three pedals and no automation, that is, the transmission is completely subordinate to the driver. At the same time, many car enthusiasts constantly argue about whether it is necessary to depress the clutch when starting the engine. This question sometimes confuses not only beginners, but also experienced drivers. Let's figure it out.

Read in this article

Crack in the friction lining / excessive rotation speed

Cause:

driving with the clutch pedal depressed at high speed in low gear;

incorrect gear switching from high to low;

Result:

Friction lining fragments get stuck in the flywheel or pressure plate housing;

Note:

the rotation speed of the friction linings exceeds the maximum permissible by 1.7-2 times. Overheated linings crack at an early stage.

Why does the clutch disappear?

Let's look at the main reasons why clutch disappears. Let's start with the option when the transmission does not disconnect from the engine when you try to press the pedal.

Hydraulic seal is broken. First of all, check the fluid level in the expansion tank. If the level is critically low or there is no liquid, we inspect the systems for leaks.
The cable on the mechanical clutch drive broke. If the clutch suddenly disappears, and your car has a mechanical drive, there is a high probability that the cable has broken. In this case, you need to visually check the integrity of the drive cable.
The cuffs of the clutch master or slave cylinder are damaged. When you press the pedal, the liquid will simply flow inside one of the cylinders without creating force. But the fluid level in the expansion tank may be normal. Diagnosis of this malfunction requires removing the cylinder and disassembling it.
The drive adjustment is incorrect. This applies to manual and/or fork driven clutches. Sometimes the extension of the working cylinder rod or the tension of the cable is not enough for full squeezing. In this case, adjustment of the clutch drive will be required.
The clutch fork is bent or broken. If the clutch suddenly disappears while driving after pressing the pedal, the cause may be damage to the fork. Relevant for cars in which the release bearing is not paired with the cylinder.
The petals on the pressure plate broke off or sagged critically. Such a breakdown can only be diagnosed after dismantling the gearbox and inspecting the clutch basket.

Let's look at cases where the concept of “lost clutch” refers to failures in the transmission of torque from the engine to the gearbox.

Mechanical wear of the friction linings of the driven disk. The coefficient of adhesion between the clutch discs decreases, which leads to their slipping.
Loss of stiffness of the pressure plate diaphragm spring. The friction (driven) disc does not press well against the flywheel, which leads to clutch slipping.

In the first two cases, the malfunction is often accompanied by a burning smell from the friction material of the driven disk, which appears from friction at high speed. Usually the clutch disappears at speed, when climbing a mountain or when changing the throttle. The engine runs at noticeably higher speeds for the selected gear. Moreover, the speed often fluctuates, and the car jerks.

Drive problems. If the clutch drive does not operate correctly (or is incorrectly adjusted), the release bearing may support the pressure plate petals. In this case, the clamping force will become lower than normal and the clutch will begin to slip. In the hydraulic version of the drive, there is a tendency that the clutch more often disappears when cold (or works worse in the cold season). The working fluid is more viscous in cold weather, and the defective pressure release system when releasing the pedal works especially poorly in this case. That is, the clutch remains partially “squeezed” even when the pedal is released. If the release bearing is supported in the mechanical version of the drive, mutual slipping of the disks is observed regardless of the ambient temperature.

In any case, clutch problems should be solved as quickly as possible, or better yet, immediately after they appear. After all, this system is critically important, and its failure will immobilize the car.

Spare parts for clutches of Russian and imported cars at a low price in a wide range are presented in the online store TopDetal.ru.

Fracture of torsion springs due to overload

Note:

driving a car in a low range of engine speeds. Driving at low speed and with a full load in high gear;

too much uneven operation of the engine;

transmission joints are worn;

Result:

debris is thrown out and jammed in the friction linings.

Depressing the clutch when starting the engine: all the pros and cons

As a rule, the habit of squeezing the clutch before starting the engine for many drivers who drive a car with a manual transmission is an action that has been brought to full automaticity. The clutch is always depressed, regardless of the time of year, etc.

At the same time, although less often, there are car owners who categorically do not recommend constantly depressing the clutch pedal before starting the engine. Let's consider the arguments of one and the other side.

Let's start with the supporters of the squeeze. Without going into technical details, by pressing the clutch pedal, the driver completely “opens” the gearbox and the engine.

It is for this reason that those who have been accustomed to driving cars since the times of the USSR are well aware that it is easier for the starter to turn with the clutch depressed, since the input shaft in the box does not rotate when the clutch is depressed.

Engine speed and service life. Disadvantages of driving at low and high speeds. At what engine speed is it best to drive? Tips and tricks.

To warm up or not to warm up the engine in winter before driving. Why the engine should be warmed up, how to properly warm up the engine before driving and while driving.

The ends of the diaphragm spring / release bearing fork are ground off

Cause:

the release bearing guide bushing is faulty;

the engine and gearbox are not aligned correctly;

Result:

Constant impacts of the release bearing on the ends of the diaphragm spring lead to wear of the basket. A similar situation can be observed on the release bearing fork.

Knocks and extraneous noises

Rattling, tapping and other noises during switching on may be due to:

Sufficiently large settlement, defects or damage to the damper springs (vibration damping mechanism);

wear (depletion) of openings for damper springs;

deterioration or damage, deformation of the linings;

loosening the fastening rivets securing the linings;

deformation or damage to the HP surface.

All of the above problems are eliminated when replacing the VD with a new analogue. In some cases, extraneous noise may be caused by a lack of lubrication, or damage due to wear, or significant deformation of the release bearing housing. Accordingly, to eliminate the malfunction, you will have to replace the bearing.

Pedal creaking

can happen in two cases:

lack of lubrication on plastic bushings;

high wear (wear) of bushings.

For lubrication, CV joints-4 or Litol-24 are usually used. When replacing damaged elements with new analogues, they must also be treated with lubricant. It very rarely happens that the fork can bend strongly as a result of deformation and then the clutch pedal simply cannot be pressed. In such cases, it is recommended to simply replace the damaged part.

Pressure plate broken / severe overheating

Cause:

constant slipping of the clutch;

Clutch compression force is too low;

tight movement or lack of clearance between the bearings and the release levers;

oiling/salting;

large opening in the flywheel;

Result:

insufficient pressing of the pressure plate.