If, when pressing the clutch pedal and trying to engage a gear, a shrill noise is heard (the well-known 'grinding'), what is it usually due to?

Question

DentroTest · Accepted Answer

The function of the synchronizer ring in a manual gearbox is to match the rotational speed of the gear wheel of the selected gear with that of the output shaft before engagement takes place. If the synchronizer of a particular gear is worn or damaged, it fails to match those speeds in time and the teeth of the gears clash with each other, which produces the 'grinding' noise. Broken springs in the sliding parts are not the usual cause: they tend to cause difficulty in disengaging the gear or other mechanical faults. And assuming that a single mechanism synchronizes all the gears is a mistake, because each gear or group of gears has its own synchronizer.

If, when pressing the clutch pedal and trying to engage a gear, a shrill noise is heard (the well-known 'grinding'), what is it usually due to?

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