Master told what danger conceals the crunch in the gearbox

Мастер рассказал, какую опасность таит хруст в коробке передач

Features transmissions in used cars can be different. But there are some symptoms, which can lead to serious repair.

Expert and head of the original service “UkrAVTO” Alexander Chalenko told on what points you should pay attention immediately and what they report.

The first gear is engaged with a crunch at speed above 10 km/h and second gear at that speed pulls hard. What could be a crunch?

Based on symptoms you can identify a few main reasons why this can happen:

  1. Feature manual transmission, variable transmission;
  2. The failure of manual transmission;
  3. Malfunction of the clutch.

Mechanism that provides smooth gear shifting due to the alignment of frequency of rotation of the shaft and gears are called the synchronizer. Its objective is to reduce the wear of gear rims of the clutch switch and gear by reducing impact loads on teeth. Reduces acoustic noise (crunching, grinding sound) when changing gears. Prolongs the life of the KP.

Considering the structural feature, we will focus on the boxes is not quite up to date, where there is no synchronizer on first gear or in the box they do not (unsynchronized KP). Turning to the theoretical part, it is not difficult to imagine that happening on a box like this when in first gear while driving. Frequency of the shaft and gears are different and to equalize it only using the technique clutch dual operation with “blipping”. Otherwise, we fail to put it in gear or does it happen with too much force, which will be accompanied by the crunching and grinding from the box. Therefore, the recommendation of service is to start moving from first gear, bring the engine speed to such that it was enough to shift into second gear.

Under a fault manual gearbox, understand the wear or breakage of the couplings of synchronizers. In this case, you must contact the service center for necessary repairs. You will need to remove gearbox, disassemble and change worn-out mechanisms and details.

Under the failure of adhesion, we understand that it is not until the end off. Requires additional diagnosis before replacement.

This is probably the most common fault. But in fact there are many more. Therefore, when faced with this problem, you should immediately turn to a service station to carry out diagnostic and repair work, in order not to aggravate the fault, if any.

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