Transmission malfunctions

This article deals with manual transmission malfunctions and where to drop off old license plates. Faults of automatic transmission, robot transmission and variator, will be covered in other pages.


Manual transmission installed in modern passenger cars has significant differences in design and, accordingly, individual faults. At the same time, it is possible to identify common malfunctions of the manual transmission. Conventionally, they can be divided into malfunctions of the gearbox itself and malfunctions of the gearshift mechanism. General gearbox faults include:


wear of the synchronizer clutches;

wear of the splined joints of the synchronizer clutches;

worn gears;

low oil level in the gearbox;

wear of bearings of drive shaft, idler shaft, intermediate shaft;

looseness of gearbox mounting bolts;

wear of glands.


Malfunctions of the gearshift mechanism include:


loosening of fastening, jamming or damage of the drive cable (rod);

wear or damage of the shift rod;

Wear or deformation of the locking mechanism;

Wear or deformation of the shift fork.


The main causes of these malfunctions are:


violation of operating rules (use of low-quality oil, operation of the vehicle with a faulty clutch);

low quality of accessories;

the gearbox is reaching the end of its service life;

unqualified execution of works on maintenance and repair of the gearbox.


Transmission malfunctions can be identified by external signs:


gearbox noise;

Difficulty in engagement of gears;

Spontaneous disengaging of gears;

oil leakage.


Noise in the gearbox can appear in different conditions – in neutral position, when engaging gears, when the box is running. Each of these noises indicates certain malfunctions of the manual transmission.


When diagnosing it is necessary to remember that one external sign may correspond to several gearbox malfunctions. Therefore, the establishment of a particular fault is usually performed when dismantling and disassembling the box. Carrying out defects and repair of the box presupposes high qualification of the executor.


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