Noise localization
Before attempting to repair the clutch or transaxle assembly, find out the cause of any noises.
Signs of a failing clutch or manual transmission:
- More effort is needed to shift gears.
- Metallic clang of gears at the moment of shifting.
- Gear lock.
If any of the above symptoms occur, a thorough fault analysis should be carried out. Before dismantling the clutch or gearbox, the following checks must be made.
Definition of traffic noise
Many noises that at first glance appear to come from the checkpoint actually come from other sources, such as:
- Tires.
- Road surface.
- Wheel bearings.
- Engine.
- System of release of the fulfilled gases.
These noises can vary depending on:
- Vehicle dimensions.
- Vehicle type.
- The amount of soundproofing material used in the car.
Noises at the checkpoint
A gearbox, like any mechanical device, is not completely silent and makes some noise during normal operation.
To identify suspicious checkpoint noise, you must:
1. Select a level road to reduce tire noise and body vibration.
2. Drive some distance long enough to heat up the oil.
3. Note the speed and gear at which the noise occurs.
4. Check for noise with the vehicle stopped and the engine running.
5. Determine in what modes of motion noise occurs:
- In acceleration mode.
- In constant speed mode (the throttle valve is slightly open, the car is moving on a level road without a slope).
- In coasting mode (Gearbox at speed, throttle partially or fully closed).
- In all modes described above.
Bearing noise
Differential side bearing noise
Noises emanating from the side bearings of the differential and from the wheel bearings are very similar. Since the side bearings are assembled with preload, the noise coming from them should not be significantly reduced if the gearbox and differential are operated with the vehicle elevated (wheels don't touch the road).
Wheel bearing noise
The wheel bearing produces a specific grinding noise that is also heard when the car is coasting when the gear is in neutral. Since the wheel bearing is assembled without preload, the noise coming from it should be reduced if the car is suspended (wheels don't touch the road).
Other noise
Indentation on rolling surfaces of bearings (brinelling)
A brinelled bearing is a source of knocking that occurs once every two revolutions of the wheel, which is explained by the difference in the speed of the wheel and the bearing elements. When the vehicle is moving, bearing knock is perceived as a low-frequency noise.
Bearing knock is caused by the formation of dents in the bearing treadmill from balls under excessive load. Bearing brinelling can also occur if, when one ring is pressed in, pressure is simultaneously applied to the second bearing ring.
Vibrations in the bearing area may be mistaken for bearing knocking. A sign of brinelling is the presence of dents on the rolling surfaces of the bearing.
Bearing wear
Abrasion of bearings can occur as a result of the ingress of abrasive particles, such as scale, sand or emery with oil. As a result, the rolling surfaces wear out. Abrasion of bearings, which still operate without shock and have no cracks or pits, is the result of oil contamination.
Blocking
Entry of large particles of foreign material between the balls and the bearing ring often causes the bearing to lock up and one of the rings to rotate, resulting in noise. Excessive preload on a tapered roller bearing can also cause the bearing to lock up.
Pitting
The pitting of the rolling surfaces is the result of normal wear and the ingress of foreign particles.
Chipping
This bearing defect is characterized by material flaking or pitting on the surface of balls or rings as a result of overloading or improper assembly, which can result in misalignment, misalignment or increased friction in the bearing.
After completing the above checks, go to the subsection "Diagnostic cards" in this section.